Gitiles
Code Review Sign In
git01.mediatek.com / haproxy / d909078dec09ea7636bc1b0fce536303f146ed5f / . / doc / lua-api / index.rst
blob: e0bda2dc89631f145909e72faca19491a4a121ef [file] [log] [blame]
.. toctree::
:maxdepth: 2
How Lua runs in HAProxy
=======================
HAProxy Lua running contexts
----------------------------
The Lua code executed in HAProxy can be processed in 2 main modes. The first one
is the **initialisation mode**, and the second is the **runtime mode**.
* In the **initialisation mode**, we can perform DNS solves, but we cannot
perform socket I/O. In this initialisation mode, HAProxy still blocked during
the execution of the Lua program.
* In the **runtime mode**, we cannot perform DNS solves, but we can use sockets.
The execution of the Lua code is multiplexed with the requests processing, so
the Lua code seems to be run in blocking, but it is not the case.
The Lua code is loaded in one or more files. These files contains main code and
functions. Lua have 6 execution context.
1. The Lua file **body context**. It is executed during the load of the Lua file
in the HAProxy `[global]` section with the directive `lua-load`. It is
executed in initialisation mode. This section is use for configuring Lua
bindings in HAProxy.
2. The Lua **init context**. It is a Lua function executed just after the
HAProxy configuration parsing. The execution is in initialisation mode. In
this context the HAProxy environment are already initialized. It is useful to
check configuration, or initializing socket connections or tasks. These
functions are declared in the body context with the Lua function
`core.register_init()`. The prototype of the function is a simple function
without return value and without parameters, like this: `function fcn()`.
3. The Lua **task context**. It is a Lua function executed after the start
of the HAProxy scheduler, and just after the declaration of the task with the
Lua function `core.register_task()`. This context can be concurrent with the
traffic processing. It is executed in runtime mode. The prototype of the
function is a simple function without return value and without parameters,
like this: `function fcn()`.
4. The **action context**. It is a Lua function conditionally executed. These
actions are registered by the Lua directives "`core.register_action()`". The
prototype of the Lua called function is a function with doesn't returns
anything and that take an object of class TXN as entry. `function fcn(txn)`.
5. The **sample-fetch context**. This function takes a TXN object as entry
argument and returns a string. These types of function cannot execute any
blocking function. They are useful to aggregate some of original HAProxy
sample-fetches and return the result. The prototype of the function is
`function string fcn(txn)`. These functions can be registered with the Lua
function `core.register_fetches()`. Each declared sample-fetch is prefixed by
the string "lua.".
**NOTE**: It is possible that this function cannot found the required data
in the original HAProxy sample-fetches, in this case, it cannot return the
result. This case is not yet supported
6. The **converter context**. It is a Lua function that takes a string as input
and returns another string as output. These types of function are stateless,
it cannot access to any context. They don't execute any blocking function.
The call prototype is `function string fcn(string)`. This function can be
registered with the Lua function `core.register_converters()`. Each declared
converter is prefixed by the string "lua.".
HAProxy Lua Hello world
-----------------------
HAProxy configuration file (`hello_world.conf`):
::
global
lua-load hello_world.lua
listen proxy
bind 127.0.0.1:10001
tcp-request inspect-delay 1s
tcp-request content use-service lua.hello_world
HAProxy Lua file (`hello_world.lua`):
.. code-block:: lua
core.register_service("hello_world", "tcp", function(applet)
applet:send("hello world\n")
end)
How to start HAProxy for testing this configuration:
::
./haproxy -f hello_world.conf
On other terminal, you can test with telnet:
::
#:~ telnet 127.0.0.1 10001
hello world
Core class
==========
.. js:class:: core
The "core" class contains all the HAProxy core functions. These function are
useful for the controlling the execution flow, registering hooks, manipulating
global maps or ACL, ...
"core" class is basically provided with HAProxy. No `require` line is
required to uses these function.
The "core" class is static, it is not possible to create a new object of this
type.
.. js:attribute:: core.emerg
:returns: integer
This attribute is an integer, it contains the value of the loglevel "emergency" (0).
.. js:attribute:: core.alert
:returns: integer
This attribute is an integer, it contains the value of the loglevel "alert" (1).
.. js:attribute:: core.crit
:returns: integer
This attribute is an integer, it contains the value of the loglevel "critical" (2).
.. js:attribute:: core.err
:returns: integer
This attribute is an integer, it contains the value of the loglevel "error" (3).
.. js:attribute:: core.warning
:returns: integer
This attribute is an integer, it contains the value of the loglevel "warning" (4).
.. js:attribute:: core.notice
:returns: integer
This attribute is an integer, it contains the value of the loglevel "notice" (5).
.. js:attribute:: core.info
:returns: integer
This attribute is an integer, it contains the value of the loglevel "info" (6).
.. js:attribute:: core.debug
:returns: integer
This attribute is an integer, it contains the value of the loglevel "debug" (7).
.. js:attribute:: core.proxies
**context**: task, action, sample-fetch, converter
This attribute is a table of declared proxies (frontend and backends). Each
proxy give an access to his list of listeners and servers. The table is
indexed by proxy name, and each entry is of type :ref:`proxy_class`.
Warning, if you are declared frontend and backend with the same name, only one
of these are listed.
:see: :js:attr:`core.backends`
:see: :js:attr:`core.frontends`
.. js:attribute:: core.backends
**context**: task, action, sample-fetch, converter
This attribute is a table of declared proxies with backend capability. Each
proxy give an access to his list of listeners and servers. The table is
indexed by the backend name, and each entry is of type :ref:`proxy_class`.
:see: :js:attr:`core.proxies`
:see: :js:attr:`core.frontends`
.. js:attribute:: core.frontends
**context**: task, action, sample-fetch, converter
This attribute is a table of declared proxies with frontend capability. Each
proxy give an access to his list of listeners and servers. The table is
indexed by the frontend name, and each entry is of type :ref:`proxy_class`.
:see: :js:attr:`core.proxies`
:see: :js:attr:`core.backends`
.. js:attribute:: core.thread
**context**: task, action, sample-fetch, converter, applet
This variable contains the executing thread number starting at 1. 0 is a
special case for the common lua context. So, if thread is 0, Lua scope is
shared by all threads, otherwise the scope is dedicated to a single thread.
A program which needs to execute some parts exactly once regardless of the
number of threads can check that core.thread is 0 or 1.
.. js:function:: core.log(loglevel, msg)
**context**: body, init, task, action, sample-fetch, converter
This function sends a log. The log is sent, according with the HAProxy
configuration file, on the default syslog server if it is configured and on
the stderr if it is allowed.
:param integer loglevel: Is the log level associated with the message. It is a
number between 0 and 7.
:param string msg: The log content.
:see: :js:attr:`core.emerg`, :js:attr:`core.alert`, :js:attr:`core.crit`,
:js:attr:`core.err`, :js:attr:`core.warning`, :js:attr:`core.notice`,
:js:attr:`core.info`, :js:attr:`core.debug` (log level definitions)
:see: :js:func:`core.Debug`
:see: :js:func:`core.Info`
:see: :js:func:`core.Warning`
:see: :js:func:`core.Alert`
.. js:function:: core.Debug(msg)
**context**: body, init, task, action, sample-fetch, converter
:param string msg: The log content.
:see: :js:func:`core.log`
Does the same job than:
.. code-block:: lua
function Debug(msg)
core.log(core.debug, msg)
end
..
.. js:function:: core.Info(msg)
**context**: body, init, task, action, sample-fetch, converter
:param string msg: The log content.
:see: :js:func:`core.log`
.. code-block:: lua
function Info(msg)
core.log(core.info, msg)
end
..
.. js:function:: core.Warning(msg)
**context**: body, init, task, action, sample-fetch, converter
:param string msg: The log content.
:see: :js:func:`core.log`
.. code-block:: lua
function Warning(msg)
core.log(core.warning, msg)
end
..
.. js:function:: core.Alert(msg)
**context**: body, init, task, action, sample-fetch, converter
:param string msg: The log content.
:see: :js:func:`core.log`
.. code-block:: lua
function Alert(msg)
core.log(core.alert, msg)
end
..
.. js:function:: core.add_acl(filename, key)
**context**: init, task, action, sample-fetch, converter
Add the ACL *key* in the ACLs list referenced by the file *filename*.
:param string filename: the filename that reference the ACL entries.
:param string key: the key which will be added.
.. js:function:: core.del_acl(filename, key)
**context**: init, task, action, sample-fetch, converter
Delete the ACL entry referenced by the key *key* in the list of ACLs
referenced by *filename*.
:param string filename: the filename that reference the ACL entries.
:param string key: the key which will be deleted.
.. js:function:: core.del_map(filename, key)
**context**: init, task, action, sample-fetch, converter
Delete the map entry indexed with the specified key in the list of maps
referenced by his filename.
:param string filename: the filename that reference the map entries.
:param string key: the key which will be deleted.
.. js:function:: core.get_info()
**context**: body, init, task, action, sample-fetch, converter
Returns HAProxy core information. We can found information like the uptime,
the pid, memory pool usage, tasks number, ...
These information are also returned by the management socket via the command
"show info". See the management socket documentation for more information
about the content of these variables.
:returns: an array of values.
.. js:function:: core.now()
**context**: body, init, task, action
This function returns the current time. The time returned is fixed by the
HAProxy core and assures than the hour will be monotonic and that the system
call 'gettimeofday' will not be called too. The time is refreshed between each
Lua execution or resume, so two consecutive call to the function "now" will
probably returns the same result.
:returns: a table which contains two entries "sec" and "usec". "sec"
contains the current at the epoch format, and "usec" contains the
current microseconds.
.. js:function:: core.http_date(date)
**context**: body, init, task, action
This function take a string representing http date, and returns an integer
containing the corresponding date with a epoch format. A valid http date
me respect the format IMF, RFC850 or ASCTIME.
:param string date: a date http-date formatted
:returns: integer containing epoch date
:see: :js:func:`core.imf_date`.
:see: :js:func:`core.rfc850_date`.
:see: :js:func:`core.asctime_date`.
:see: https://tools.ietf.org/html/rfc7231#section-7.1.1.1
.. js:function:: core.imf_date(date)
**context**: body, init, task, action
This function take a string representing IMF date, and returns an integer
containing the corresponding date with a epoch format.
:param string date: a date IMF formatted
:returns: integer containing epoch date
:see: https://tools.ietf.org/html/rfc7231#section-7.1.1.1
The IMF format is like this:
.. code-block:: text
Sun, 06 Nov 1994 08:49:37 GMT
..
.. js:function:: core.rfc850_date(date)
**context**: body, init, task, action
This function take a string representing RFC850 date, and returns an integer
containing the corresponding date with a epoch format.
:param string date: a date RFC859 formatted
:returns: integer containing epoch date
:see: https://tools.ietf.org/html/rfc7231#section-7.1.1.1
The RFC850 format is like this:
.. code-block:: text
Sunday, 06-Nov-94 08:49:37 GMT
..
.. js:function:: core.asctime_date(date)
**context**: body, init, task, action
This function take a string representing ASCTIME date, and returns an integer
containing the corresponding date with a epoch format.
:param string date: a date ASCTIME formatted
:returns: integer containing epoch date
:see: https://tools.ietf.org/html/rfc7231#section-7.1.1.1
The ASCTIME format is like this:
.. code-block:: text
Sun Nov 6 08:49:37 1994
..
.. js:function:: core.rfc850_date(date)
**context**: body, init, task, action
This function take a string representing http date, and returns an integer
containing the corresponding date with a epoch format.
:param string date: a date http-date formatted
.. js:function:: core.asctime_date(date)
**context**: body, init, task, action
This function take a string representing http date, and returns an integer
containing the corresponding date with a epoch format.
:param string date: a date http-date formatted
.. js:function:: core.msleep(milliseconds)
**context**: body, init, task, action
The `core.msleep()` stops the Lua execution between specified milliseconds.
:param integer milliseconds: the required milliseconds.
.. js:attribute:: core.proxies
**context**: body, init, task, action, sample-fetch, converter
Proxies is a table containing the list of all proxies declared in the
configuration file. The table is indexed by the proxy name, and each entry
of the proxies table is an object of type :ref:`proxy_class`.
Warning, if you have declared a frontend and backend with the same name, only
one of these are listed.
.. js:function:: core.register_action(name, actions, func [, nb_args])
**context**: body
Register a Lua function executed as action. All the registered action can be
used in HAProxy with the prefix "lua.". An action gets a TXN object class as
input.
:param string name: is the name of the converter.
:param table actions: is a table of string describing the HAProxy actions who
want to register to. The expected actions are 'tcp-req',
'tcp-res', 'http-req' or 'http-res'.
:param integer nb_args: is the expected number of argument for the action.
By default the value is 0.
:param function func: is the Lua function called to work as converter.
The prototype of the Lua function used as argument is:
.. code-block:: lua
function(txn [, arg1 [, arg2]])
..
* **txn** (:ref:`txn_class`): this is a TXN object used for manipulating the
current request or TCP stream.
* **argX**: this is argument provided through the HAProxy configuration file.
Here, an example of action registration. The action just send an 'Hello world'
in the logs.
.. code-block:: lua
core.register_action("hello-world", { "tcp-req", "http-req" }, function(txn)
txn:Info("Hello world")
end)
..
This example code is used in HAProxy configuration like this:
::
frontend tcp_frt
mode tcp
tcp-request content lua.hello-world
frontend http_frt
mode http
http-request lua.hello-world
..
A second example using arguments
.. code-block:: lua
function hello_world(txn, arg)
txn:Info("Hello world for " .. arg)
end
core.register_action("hello-world", { "tcp-req", "http-req" }, hello_world, 2)
..
This example code is used in HAProxy configuration like this:
::
frontend tcp_frt
mode tcp
tcp-request content lua.hello-world everybody
..
.. js:function:: core.register_converters(name, func)
**context**: body
Register a Lua function executed as converter. All the registered converters
can be used in HAProxy with the prefix "lua.". An converter get a string as
input and return a string as output. The registered function can take up to 9
values as parameter. All the value are strings.
:param string name: is the name of the converter.
:param function func: is the Lua function called to work as converter.
The prototype of the Lua function used as argument is:
.. code-block:: lua
function(str, [p1 [, p2 [, ... [, p5]]]])
..
* **str** (*string*): this is the input value automatically converted in
string.
* **p1** .. **p5** (*string*): this is a list of string arguments declared in
the HAProxy configuration file. The number of arguments doesn't exceed 5.
The order and the nature of these is conventionally choose by the
developer.
.. js:function:: core.register_fetches(name, func)
**context**: body
Register a Lua function executed as sample fetch. All the registered sample
fetch can be used in HAProxy with the prefix "lua.". A Lua sample fetch
return a string as output. The registered function can take up to 9 values as
parameter. All the value are strings.
:param string name: is the name of the converter.
:param function func: is the Lua function called to work as sample fetch.
The prototype of the Lua function used as argument is:
.. code-block:: lua
string function(txn, [p1 [, p2 [, ... [, p5]]]])
..
* **txn** (:ref:`txn_class`): this is the txn object associated with the current
request.
* **p1** .. **p5** (*string*): this is a list of string arguments declared in
the HAProxy configuration file. The number of arguments doesn't exceed 5.
The order and the nature of these is conventionally choose by the
developer.
* **Returns**: A string containing some data, or nil if the value cannot be
returned now.
lua example code:
.. code-block:: lua
core.register_fetches("hello", function(txn)
return "hello"
end)
..
HAProxy example configuration:
::
frontend example
http-request redirect location /%[lua.hello]
.. js:function:: core.register_service(name, mode, func)
**context**: body
Register a Lua function executed as a service. All the registered service can
be used in HAProxy with the prefix "lua.". A service gets an object class as
input according with the required mode.
:param string name: is the name of the converter.
:param string mode: is string describing the required mode. Only 'tcp' or
'http' are allowed.
:param function func: is the Lua function called to work as converter.
The prototype of the Lua function used as argument is:
.. code-block:: lua
function(applet)
..
* **applet** *applet* will be a :ref:`applettcp_class` or a
:ref:`applethttp_class`. It depends the type of registered applet. An applet
registered with the 'http' value for the *mode* parameter will gets a
:ref:`applethttp_class`. If the *mode* value is 'tcp', the applet will gets
a :ref:`applettcp_class`.
**warning**: Applets of type 'http' cannot be called from 'tcp-*'
rulesets. Only the 'http-*' rulesets are authorized, this means
that is not possible to call an HTTP applet from a proxy in tcp
mode. Applets of type 'tcp' can be called from anywhere.
Here, an example of service registration. The service just send an 'Hello world'
as an http response.
.. code-block:: lua
core.register_service("hello-world", "http", function(applet)
local response = "Hello World !"
applet:set_status(200)
applet:add_header("content-length", string.len(response))
applet:add_header("content-type", "text/plain")
applet:start_response()
applet:send(response)
end)
..
This example code is used in HAProxy configuration like this:
::
frontend example
http-request use-service lua.hello-world
.. js:function:: core.register_init(func)
**context**: body
Register a function executed after the configuration parsing. This is useful
to check any parameters.
:param function func: is the Lua function called to work as initializer.
The prototype of the Lua function used as argument is:
.. code-block:: lua
function()
..
It takes no input, and no output is expected.
.. js:function:: core.register_task(func)
**context**: body, init, task, action, sample-fetch, converter
Register and start independent task. The task is started when the HAProxy
main scheduler starts. For example this type of tasks can be executed to
perform complex health checks.
:param function func: is the Lua function called to work as initializer.
The prototype of the Lua function used as argument is:
.. code-block:: lua
function()
..
It takes no input, and no output is expected.
.. js:function:: core.register_cli([path], usage, func)
**context**: body
Register and start independent task. The task is started when the HAProxy
main scheduler starts. For example this type of tasks can be executed to
perform complex health checks.
:param array path: is the sequence of word for which the cli execute the Lua
binding.
:param string usage: is the usage message displayed in the help.
:param function func: is the Lua function called to handle the CLI commands.
The prototype of the Lua function used as argument is:
.. code-block:: lua
function(AppletTCP, [arg1, [arg2, [...]]])
..
I/O are managed with the :ref:`applettcp_class` object. Args are given as
parameter. The args embed the registered path. If the path is declared like
this:
.. code-block:: lua
core.register_cli({"show", "ssl", "stats"}, "Display SSL stats..", function(applet, arg1, arg2, arg3, arg4, arg5)
end)
..
And we execute this in the prompt:
.. code-block:: text
> prompt
> show ssl stats all
..
Then, arg1, arg2 and arg3 will contains respectively "show", "ssl" and "stats".
arg4 will contain "all". arg5 contains nil.
.. js:function:: core.set_nice(nice)
**context**: task, action, sample-fetch, converter
Change the nice of the current task or current session.
:param integer nice: the nice value, it must be between -1024 and 1024.
.. js:function:: core.set_map(filename, key, value)
**context**: init, task, action, sample-fetch, converter
Set the value *value* associated to the key *key* in the map referenced by
*filename*.
:param string filename: the Map reference
:param string key: the key to set or replace
:param string value: the associated value
.. js:function:: core.sleep(int seconds)
**context**: body, init, task, action
The `core.sleep()` functions stop the Lua execution between specified seconds.
:param integer seconds: the required seconds.
.. js:function:: core.tcp()
**context**: init, task, action
This function returns a new object of a *socket* class.
:returns: A :ref:`socket_class` object.
.. js:function:: core.concat()
**context**: body, init, task, action, sample-fetch, converter
This function returns a new concat object.
:returns: A :ref:`concat_class` object.
.. js:function:: core.done(data)
**context**: body, init, task, action, sample-fetch, converter
:param any data: Return some data for the caller. It is useful with
sample-fetches and sample-converters.
Immediately stops the current Lua execution and returns to the caller which
may be a sample fetch, a converter or an action and returns the specified
value (ignored for actions and init). It is used when the LUA process finishes
its work and wants to give back the control to HAProxy without executing the
remaining code. It can be seen as a multi-level "return".
.. js:function:: core.yield()
**context**: task, action, sample-fetch, converter
Give back the hand at the HAProxy scheduler. It is used when the LUA
processing consumes a lot of processing time.
.. js:function:: core.parse_addr(address)
**context**: body, init, task, action, sample-fetch, converter
:param network: is a string describing an ipv4 or ipv6 address and optionally
its network length, like this: "127.0.0.1/8" or "aaaa::1234/32".
:returns: a userdata containing network or nil if an error occurs.
Parse ipv4 or ipv6 addresses and its facultative associated network.
.. js:function:: core.match_addr(addr1, addr2)
**context**: body, init, task, action, sample-fetch, converter
:param addr1: is an address created with "core.parse_addr".
:param addr2: is an address created with "core.parse_addr".
:returns: boolean, true if the network of the addresses match, else returns
false.
Match two networks. For example "127.0.0.1/32" matches "127.0.0.0/8". The order
of network is not important.
.. js:function:: core.tokenize(str, separators [, noblank])
**context**: body, init, task, action, sample-fetch, converter
This function is useful for tokenizing an entry, or splitting some messages.
:param string str: The string which will be split.
:param string separators: A string containing a list of separators.
:param boolean noblank: Ignore empty entries.
:returns: an array of string.
For example:
.. code-block:: lua
local array = core.tokenize("This function is useful, for tokenizing an entry.", "., ", true)
print_r(array)
..
Returns this array:
.. code-block:: text
(table) table: 0x21c01e0 [
1: (string) "This"
2: (string) "function"
3: (string) "is"
4: (string) "useful"
5: (string) "for"
6: (string) "tokenizing"
7: (string) "an"
8: (string) "entry"
]
..
.. _proxy_class:
Proxy class
============
.. js:class:: Proxy
This class provides a way for manipulating proxy and retrieving information
like statistics.
.. js:attribute:: Proxy.name
Contain the name of the proxy.
.. js:attribute:: Proxy.uuid
Contain the unique identifier of the proxy.
.. js:attribute:: Proxy.servers
Contain a table with the attached servers. The table is indexed by server
name, and each server entry is an object of type :ref:`server_class`.
.. js:attribute:: Proxy.stktable
Contains a stick table object attached to the proxy.
.. js:attribute:: Proxy.listeners
Contain a table with the attached listeners. The table is indexed by listener
name, and each each listeners entry is an object of type
:ref:`listener_class`.
.. js:function:: Proxy.pause(px)
Pause the proxy. See the management socket documentation for more information.
:param class_proxy px: A :ref:`proxy_class` which indicates the manipulated
proxy.
.. js:function:: Proxy.resume(px)
Resume the proxy. See the management socket documentation for more
information.
:param class_proxy px: A :ref:`proxy_class` which indicates the manipulated
proxy.
.. js:function:: Proxy.stop(px)
Stop the proxy. See the management socket documentation for more information.
:param class_proxy px: A :ref:`proxy_class` which indicates the manipulated
proxy.
.. js:function:: Proxy.shut_bcksess(px)
Kill the session attached to a backup server. See the management socket
documentation for more information.
:param class_proxy px: A :ref:`proxy_class` which indicates the manipulated
proxy.
.. js:function:: Proxy.get_cap(px)
Returns a string describing the capabilities of the proxy.
:param class_proxy px: A :ref:`proxy_class` which indicates the manipulated
proxy.
:returns: a string "frontend", "backend", "proxy" or "ruleset".
.. js:function:: Proxy.get_mode(px)
Returns a string describing the mode of the current proxy.
:param class_proxy px: A :ref:`proxy_class` which indicates the manipulated
proxy.
:returns: a string "tcp", "http", "health" or "unknown"
.. js:function:: Proxy.get_stats(px)
Returns a table containing the proxy statistics. The statistics returned are
not the same if the proxy is frontend or a backend.
:param class_proxy px: A :ref:`proxy_class` which indicates the manipulated
proxy.
:returns: a key/value table containing stats
.. _server_class:
Server class
============
.. js:class:: Server
This class provides a way for manipulating servers and retrieving information.
.. js:attribute:: Server.name
Contain the name of the server.
.. js:attribute:: Server.puid
Contain the proxy unique identifier of the server.
.. js:function:: Server.is_draining(sv)
Return true if the server is currently draining sticky connections.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
:returns: a boolean
.. js:function:: Server.set_maxconn(sv, weight)
Dynamically change the maximum connections of the server. See the management
socket documentation for more information about the format of the string.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
:param string maxconn: A string describing the server maximum connections.
.. js:function:: Server.get_maxconn(sv, weight)
This function returns an integer representing the server maximum connections.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
:returns: an integer.
.. js:function:: Server.set_weight(sv, weight)
Dynamically change the weight of the server. See the management socket
documentation for more information about the format of the string.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
:param string weight: A string describing the server weight.
.. js:function:: Server.get_weight(sv)
This function returns an integer representing the server weight.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
:returns: an integer.
.. js:function:: Server.set_addr(sv, addr[, port])
Dynamically change the address of the server. See the management socket
documentation for more information about the format of the string.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
:param string addr: A string describing the server address.
.. js:function:: Server.get_addr(sv)
Returns a string describing the address of the server.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
:returns: A string
.. js:function:: Server.get_stats(sv)
Returns server statistics.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
:returns: a key/value table containing stats
.. js:function:: Server.shut_sess(sv)
Shutdown all the sessions attached to the server. See the management socket
documentation for more information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.set_drain(sv)
Drain sticky sessions. See the management socket documentation for more
information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.set_maint(sv)
Set maintenance mode. See the management socket documentation for more
information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.set_ready(sv)
Set normal mode. See the management socket documentation for more information
about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.check_enable(sv)
Enable health checks. See the management socket documentation for more
information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.check_disable(sv)
Disable health checks. See the management socket documentation for more
information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.check_force_up(sv)
Force health-check up. See the management socket documentation for more
information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.check_force_nolb(sv)
Force health-check nolb mode. See the management socket documentation for more
information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.check_force_down(sv)
Force health-check down. See the management socket documentation for more
information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.agent_enable(sv)
Enable agent check. See the management socket documentation for more
information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.agent_disable(sv)
Disable agent check. See the management socket documentation for more
information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.agent_force_up(sv)
Force agent check up. See the management socket documentation for more
information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.agent_force_down(sv)
Force agent check down. See the management socket documentation for more
information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. _listener_class:
Listener class
==============
.. js:function:: Listener.get_stats(ls)
Returns server statistics.
:param class_listener ls: A :ref:`listener_class` which indicates the
manipulated listener.
:returns: a key/value table containing stats
.. _concat_class:
Concat class
============
.. js:class:: Concat
This class provides a fast way for string concatenation. The way using native
Lua concatenation like the code below is slow for some reasons.
.. code-block:: lua
str = "string1"
str = str .. ", string2"
str = str .. ", string3"
..
For each concatenation, Lua:
* allocate memory for the result,
* catenate the two string copying the strings in the new memory block,
* free the old memory block containing the string which is no longer used.
This process does many memory move, allocation and free. In addition, the
memory is not really freed, it is just mark mark as unused and wait for the
garbage collector.
The Concat class provide an alternative way to concatenate strings. It uses
the internal Lua mechanism (it does not allocate memory), but it doesn't copy
the data more than once.
On my computer, the following loops spends 0.2s for the Concat method and
18.5s for the pure Lua implementation. So, the Concat class is about 1000x
faster than the embedded solution.
.. code-block:: lua
for j = 1, 100 do
c = core.concat()
for i = 1, 20000 do
c:add("#####")
end
end
..
.. code-block:: lua
for j = 1, 100 do
c = ""
for i = 1, 20000 do
c = c .. "#####"
end
end
..
.. js:function:: Concat.add(concat, string)
This function adds a string to the current concatenated string.
:param class_concat concat: A :ref:`concat_class` which contains the currently
built string.
:param string string: A new string to concatenate to the current built
string.
.. js:function:: Concat.dump(concat)
This function returns the concatenated string.
:param class_concat concat: A :ref:`concat_class` which contains the currently
built string.
:returns: the concatenated string
.. _fetches_class:
Fetches class
=============
.. js:class:: Fetches
This class contains a lot of internal HAProxy sample fetches. See the
HAProxy "configuration.txt" documentation for more information about her
usage. They are the chapters 7.3.2 to 7.3.6.
**warning** some sample fetches are not available in some context. These
limitations are specified in this documentation when they're useful.
:see: :js:attr:`TXN.f`
:see: :js:attr:`TXN.sf`
Fetches are useful for:
* get system time,
* get environment variable,
* get random numbers,
* known backend status like the number of users in queue or the number of
connections established,
* client information like ip source or destination,
* deal with stick tables,
* Established SSL information,
* HTTP information like headers or method.
.. code-block:: lua
function action(txn)
-- Get source IP
local clientip = txn.f:src()
end
..
.. _converters_class:
Converters class
================
.. js:class:: Converters
This class contains a lot of internal HAProxy sample converters. See the
HAProxy documentation "configuration.txt" for more information about her
usage. Its the chapter 7.3.1.
:see: :js:attr:`TXN.c`
:see: :js:attr:`TXN.sc`
Converters provides statefull transformation. They are useful for:
* converting input to base64,
* applying hash on input string (djb2, crc32, sdbm, wt6),
* format date,
* json escape,
* extracting preferred language comparing two lists,
* turn to lower or upper chars,
* deal with stick tables.
.. _channel_class:
Channel class
=============
.. js:class:: Channel
HAProxy uses two buffers for the processing of the requests. The first one is
used with the request data (from the client to the server) and the second is
used for the response data (from the server to the client).
Each buffer contains two types of data. The first type is the incoming data
waiting for a processing. The second part is the outgoing data already
processed. Usually, the incoming data is processed, after it is tagged as
outgoing data, and finally it is sent. The following functions provides tools
for manipulating these data in a buffer.
The following diagram shows where the channel class function are applied.
**Warning**: It is not possible to read from the response in request action,
and it is not possible to read for the request channel in response action.
.. image:: _static/channel.png
.. js:function:: Channel.dup(channel)
This function returns a string that contain the entire buffer. The data is
not remove from the buffer and can be reprocessed later.
If the buffer can't receive more data, a 'nil' value is returned.
:param class_channel channel: The manipulated Channel.
:returns: a string containing all the available data or nil.
.. js:function:: Channel.get(channel)
This function returns a string that contain the entire buffer. The data is
consumed from the buffer.
If the buffer can't receive more data, a 'nil' value is returned.
:param class_channel channel: The manipulated Channel.
:returns: a string containing all the available data or nil.
.. js:function:: Channel.getline(channel)
This function returns a string that contain the first line of the buffer. The
data is consumed. If the data returned doesn't contains a final '\n' its
assumed than its the last available data in the buffer.
If the buffer can't receive more data, a 'nil' value is returned.
:param class_channel channel: The manipulated Channel.
:returns: a string containing the available line or nil.
.. js:function:: Channel.set(channel, string)
This function replace the content of the buffer by the string. The function
returns the copied length, otherwise, it returns -1.
The data set with this function are not send. They wait for the end of
HAProxy processing, so the buffer can be full.
:param class_channel channel: The manipulated Channel.
:param string string: The data which will sent.
:returns: an integer containing the amount of bytes copied or -1.
.. js:function:: Channel.append(channel, string)
This function append the string argument to the content of the buffer. The
function returns the copied length, otherwise, it returns -1.
The data set with this function are not send. They wait for the end of
HAProxy processing, so the buffer can be full.
:param class_channel channel: The manipulated Channel.
:param string string: The data which will sent.
:returns: an integer containing the amount of bytes copied or -1.
.. js:function:: Channel.send(channel, string)
This function required immediate send of the data. Unless if the connection
is close, the buffer is regularly flushed and all the string can be sent.
:param class_channel channel: The manipulated Channel.
:param string string: The data which will sent.
:returns: an integer containing the amount of bytes copied or -1.
.. js:function:: Channel.get_in_length(channel)
This function returns the length of the input part of the buffer.
:param class_channel channel: The manipulated Channel.
:returns: an integer containing the amount of available bytes.
.. js:function:: Channel.get_out_length(channel)
This function returns the length of the output part of the buffer.
:param class_channel channel: The manipulated Channel.
:returns: an integer containing the amount of available bytes.
.. js:function:: Channel.forward(channel, int)
This function transfer bytes from the input part of the buffer to the output
part.
:param class_channel channel: The manipulated Channel.
:param integer int: The amount of data which will be forwarded.
.. js:function:: Channel.is_full(channel)
This function returns true if the buffer channel is full.
:returns: a boolean
.. _http_class:
HTTP class
==========
.. js:class:: HTTP
This class contain all the HTTP manipulation functions.
.. js:function:: HTTP.req_get_headers(http)
Returns a table containing all the request headers.
:param class_http http: The related http object.
:returns: table of headers.
:see: :js:func:`HTTP.res_get_headers`
This is the form of the returned table:
.. code-block:: lua
HTTP:req_get_headers()['<header-name>'][<header-index>] = "<header-value>"
local hdr = HTTP:req_get_headers()
hdr["host"][0] = "www.test.com"
hdr["accept"][0] = "audio/basic q=1"
hdr["accept"][1] = "audio/*, q=0.2"
hdr["accept"][2] = "*/*, q=0.1"
..
.. js:function:: HTTP.res_get_headers(http)
Returns a table containing all the response headers.
:param class_http http: The related http object.
:returns: table of headers.
:see: :js:func:`HTTP.req_get_headers`
This is the form of the returned table:
.. code-block:: lua
HTTP:res_get_headers()['<header-name>'][<header-index>] = "<header-value>"
local hdr = HTTP:req_get_headers()
hdr["host"][0] = "www.test.com"
hdr["accept"][0] = "audio/basic q=1"
hdr["accept"][1] = "audio/*, q=0.2"
hdr["accept"][2] = "*.*, q=0.1"
..
.. js:function:: HTTP.req_add_header(http, name, value)
Appends an HTTP header field in the request whose name is
specified in "name" and whose value is defined in "value".
:param class_http http: The related http object.
:param string name: The header name.
:param string value: The header value.
:see: :js:func:`HTTP.res_add_header`
.. js:function:: HTTP.res_add_header(http, name, value)
Appends an HTTP header field in the response whose name is
specified in "name" and whose value is defined in "value".
:param class_http http: The related http object.
:param string name: The header name.
:param string value: The header value.
:see: :js:func:`HTTP.req_add_header`
.. js:function:: HTTP.req_del_header(http, name)
Removes all HTTP header fields in the request whose name is
specified in "name".
:param class_http http: The related http object.
:param string name: The header name.
:see: :js:func:`HTTP.res_del_header`
.. js:function:: HTTP.res_del_header(http, name)
Removes all HTTP header fields in the response whose name is
specified in "name".
:param class_http http: The related http object.
:param string name: The header name.
:see: :js:func:`HTTP.req_del_header`
.. js:function:: HTTP.req_set_header(http, name, value)
This variable replace all occurrence of all header "name", by only
one containing the "value".
:param class_http http: The related http object.
:param string name: The header name.
:param string value: The header value.
:see: :js:func:`HTTP.res_set_header`
This function does the same work as the following code:
.. code-block:: lua
function fcn(txn)
TXN.http:req_del_header("header")
TXN.http:req_add_header("header", "value")
end
..
.. js:function:: HTTP.res_set_header(http, name, value)
This variable replace all occurrence of all header "name", by only
one containing the "value".
:param class_http http: The related http object.
:param string name: The header name.
:param string value: The header value.
:see: :js:func:`HTTP.req_rep_header()`
.. js:function:: HTTP.req_rep_header(http, name, regex, replace)
Matches the regular expression in all occurrences of header field "name"
according to "regex", and replaces them with the "replace" argument. The
replacement value can contain back references like \1, \2, ... This
function works with the request.
:param class_http http: The related http object.
:param string name: The header name.
:param string regex: The match regular expression.
:param string replace: The replacement value.
:see: :js:func:`HTTP.res_rep_header()`
.. js:function:: HTTP.res_rep_header(http, name, regex, string)
Matches the regular expression in all occurrences of header field "name"
according to "regex", and replaces them with the "replace" argument. The
replacement value can contain back references like \1, \2, ... This
function works with the request.
:param class_http http: The related http object.
:param string name: The header name.
:param string regex: The match regular expression.
:param string replace: The replacement value.
:see: :js:func:`HTTP.req_rep_header()`
.. js:function:: HTTP.req_set_method(http, method)
Rewrites the request method with the parameter "method".
:param class_http http: The related http object.
:param string method: The new method.
.. js:function:: HTTP.req_set_path(http, path)
Rewrites the request path with the "path" parameter.
:param class_http http: The related http object.
:param string path: The new path.
.. js:function:: HTTP.req_set_query(http, query)
Rewrites the request's query string which appears after the first question
mark ("?") with the parameter "query".
:param class_http http: The related http object.
:param string query: The new query.
.. js:function:: HTTP.req_set_uri(http, uri)
Rewrites the request URI with the parameter "uri".
:param class_http http: The related http object.
:param string uri: The new uri.
.. js:function:: HTTP.res_set_status(http, status [, reason])
Rewrites the response status code with the parameter "code".
If no custom reason is provided, it will be generated from the status.
:param class_http http: The related http object.
:param integer status: The new response status code.
:param string reason: The new response reason (optional).
.. _txn_class:
TXN class
=========
.. js:class:: TXN
The txn class contain all the functions relative to the http or tcp
transaction (Note than a tcp stream is the same than a tcp transaction, but
an HTTP transaction is not the same than a tcp stream).
The usage of this class permits to retrieve data from the requests, alter it
and forward it.
All the functions provided by this class are available in the context
**sample-fetches** and **actions**.
.. js:attribute:: TXN.c
:returns: An :ref:`converters_class`.
This attribute contains a Converters class object.
.. js:attribute:: TXN.sc
:returns: An :ref:`converters_class`.
This attribute contains a Converters class object. The functions of
this object returns always a string.
.. js:attribute:: TXN.f
:returns: An :ref:`fetches_class`.
This attribute contains a Fetches class object.
.. js:attribute:: TXN.sf
:returns: An :ref:`fetches_class`.
This attribute contains a Fetches class object. The functions of
this object returns always a string.
.. js:attribute:: TXN.req
:returns: An :ref:`channel_class`.
This attribute contains a channel class object for the request buffer.
.. js:attribute:: TXN.res
:returns: An :ref:`channel_class`.
This attribute contains a channel class object for the response buffer.
.. js:attribute:: TXN.http
:returns: An :ref:`http_class`.
This attribute contains an HTTP class object. It is available only if the
proxy has the "mode http" enabled.
.. js:function:: TXN.log(TXN, loglevel, msg)
This function sends a log. The log is sent, according with the HAProxy
configuration file, on the default syslog server if it is configured and on
the stderr if it is allowed.
:param class_txn txn: The class txn object containing the data.
:param integer loglevel: Is the log level associated with the message. It is a
number between 0 and 7.
:param string msg: The log content.
:see: :js:attr:`core.emerg`, :js:attr:`core.alert`, :js:attr:`core.crit`,
:js:attr:`core.err`, :js:attr:`core.warning`, :js:attr:`core.notice`,
:js:attr:`core.info`, :js:attr:`core.debug` (log level definitions)
:see: :js:func:`TXN.deflog`
:see: :js:func:`TXN.Debug`
:see: :js:func:`TXN.Info`
:see: :js:func:`TXN.Warning`
:see: :js:func:`TXN.Alert`
.. js:function:: TXN.deflog(TXN, msg)
Sends a log line with the default loglevel for the proxy associated with the
transaction.
:param class_txn txn: The class txn object containing the data.
:param string msg: The log content.
:see: :js:func:`TXN.log
.. js:function:: TXN.Debug(txn, msg)
:param class_txn txn: The class txn object containing the data.
:param string msg: The log content.
:see: :js:func:`TXN.log`
Does the same job than:
.. code-block:: lua
function Debug(txn, msg)
TXN.log(txn, core.debug, msg)
end
..
.. js:function:: TXN.Info(txn, msg)
:param class_txn txn: The class txn object containing the data.
:param string msg: The log content.
:see: :js:func:`TXN.log`
.. code-block:: lua
function Debug(txn, msg)
TXN.log(txn, core.info, msg)
end
..
.. js:function:: TXN.Warning(txn, msg)
:param class_txn txn: The class txn object containing the data.
:param string msg: The log content.
:see: :js:func:`TXN.log`
.. code-block:: lua
function Debug(txn, msg)
TXN.log(txn, core.warning, msg)
end
..
.. js:function:: TXN.Alert(txn, msg)
:param class_txn txn: The class txn object containing the data.
:param string msg: The log content.
:see: :js:func:`TXN.log`
.. code-block:: lua
function Debug(txn, msg)
TXN.log(txn, core.alert, msg)
end
..
.. js:function:: TXN.get_priv(txn)
Return Lua data stored in the current transaction (with the `TXN.set_priv()`)
function. If no data are stored, it returns a nil value.
:param class_txn txn: The class txn object containing the data.
:returns: the opaque data previously stored, or nil if nothing is
available.
.. js:function:: TXN.set_priv(txn, data)
Store any data in the current HAProxy transaction. This action replace the
old stored data.
:param class_txn txn: The class txn object containing the data.
:param opaque data: The data which is stored in the transaction.
.. js:function:: TXN.set_var(TXN, var, value[, ifexist])
Converts a Lua type in a HAProxy type and store it in a variable <var>.
:param class_txn txn: The class txn object containing the data.
:param string var: The variable name according with the HAProxy variable syntax.
:param type value: The value associated to the variable. The type can be string or
integer.
:param boolean ifexist: If this parameter is set to a truthy value the variable
will only be set if it was defined elsewhere (i.e. used
within the configuration). It is highly recommended to
always set this to true.
.. js:function:: TXN.unset_var(TXN, var)
Unset the variable <var>.
:param class_txn txn: The class txn object containing the data.
:param string var: The variable name according with the HAProxy variable syntax.
.. js:function:: TXN.get_var(TXN, var)
Returns data stored in the variable <var> converter in Lua type.
:param class_txn txn: The class txn object containing the data.
:param string var: The variable name according with the HAProxy variable syntax.
.. js:function:: TXN.reply([reply])
Return a new reply object
:param table reply: A table containing info to initialize the reply fields.
:returns: A :ref:`reply_class` object.
The table used to initialized the reply object may contain following entries :
* status : The reply status code. the code 200 is used by default.
* reason : The reply reason. The reason corresponding to the status code is
used by default.
* headers : An list of headers, indexed by header name. Empty by default. For
a given name, multiple values are possible, stored in an ordered list.
* body : The reply body, empty by default.
.. code-block:: lua
local reply = txn:reply{
status = 400,
reason = "Bad request",
headers = {
["content-type"] = { "text/html" },
["cache-control"] = {"no-cache", "no-store" }
},
body = "<html><body><h1>invalid request<h1></body></html>"
}
..
:see: :js:class:`Reply`
.. js:function:: TXN.done(txn[, reply])
This function terminates processing of the transaction and the associated
session and optionally reply to the client for HTTP sessions.
:param class_txn txn: The class txn object containing the data.
:param class_reply reply: The class reply object to return to the client.
This functions can be used when a critical error is detected or to terminate
processing after some data have been returned to the client (eg: a redirect).
To do so, a reply may be provided. This object is optional and may contain a
status code, a reason, a header list and a body. All these fields are
optionnals. When not provided, the default values are used. By default, with
an empty reply object, an empty HTTP 200 response is returned to the
client. If no reply object is provided, the transaction is terminated without
any reply.
The reply object may be fully created in lua or the class Reply may be used to
create it.
.. code-block:: lua
local reply = txn:reply()
reply:set_status(400, "Bad request")
reply:add_header("content-type", "text/html")
reply:add_header("cache-control", "no-cache")
reply:add_header("cache-control", "no-store")
reply:set_body("<html><body><h1>invalid request<h1></body></html>")
txn:done(reply)
..
.. code-block:: lua
txn:done{
status = 400,
reason = "Bad request",
headers = {
["content-type"] = { "text/html" },
["cache-control"] = { "no-cache", "no-store" },
},
body = "<html><body><h1>invalid request<h1></body></html>"
}
..
*Warning*: It not make sense to call this function from sample-fetches. In
this case the behaviour of this one is the same than core.done(): it quit
the Lua execution. The transaction is really aborted only from an action
registered function.
:see: :js:func:`TXN.reply`, :js:class:`Reply`
.. js:function:: TXN.set_loglevel(txn, loglevel)
Is used to change the log level of the current request. The "loglevel" must
be an integer between 0 and 7.
:param class_txn txn: The class txn object containing the data.
:param integer loglevel: The required log level. This variable can be one of
:see: :js:attr:`core.emerg`, :js:attr:`core.alert`, :js:attr:`core.crit`,
:js:attr:`core.err`, :js:attr:`core.warning`, :js:attr:`core.notice`,
:js:attr:`core.info`, :js:attr:`core.debug` (log level definitions)
.. js:function:: TXN.set_tos(txn, tos)
Is used to set the TOS or DSCP field value of packets sent to the client to
the value passed in "tos" on platforms which support this.
:param class_txn txn: The class txn object containing the data.
:param integer tos: The new TOS os DSCP.
.. js:function:: TXN.set_mark(txn, mark)
Is used to set the Netfilter MARK on all packets sent to the client to the
value passed in "mark" on platforms which support it.
:param class_txn txn: The class txn object containing the data.
:param integer mark: The mark value.
.. js:function:: TXN.set_priority_class(txn, prio)
This function adjusts the priority class of the transaction. The value should
be within the range -2047..2047. Values outside this range will be
truncated.
See the HAProxy configuration.txt file keyword "http-request" action
"set-priority-class" for details.
.. js:function:: TXN.set_priority_offset(txn, prio)
This function adjusts the priority offset of the transaction. The value
should be within the range -524287..524287. Values outside this range will be
truncated.
See the HAProxy configuration.txt file keyword "http-request" action
"set-priority-offset" for details.
.. _reply_class:
Reply class
============
.. js:class:: Reply
**context**: action
This class represents an HTTP response message. It provides some methods to
enrich it.
.. code-block:: lua
local reply = txn:reply({status = 400}) -- default HTTP 400 reason-phase used
reply:add_header("content-type", "text/html")
reply:add_header("cache-control", "no-cache")
reply:add_header("cache-control", "no-store")
reply:set_body("<html><body><h1>invalid request<h1></body></html>")
..
:see: :js:func:`TXN.reply`
.. js:attribute:: Reply.status
The reply status code. By default, the status code is set to 200.
:returns: integer
.. js:attribute:: Reply.reason
The reason string describing the status code.
:returns: string
.. js:attribute:: Reply.headers
A table indexing all reply headers by name. To each name is associated an
ordered list of values.
:returns: Lua table
.. code-block:: lua
{
["content-type"] = { "text/html" },
["cache-control"] = {"no-cache", "no-store" },
x_header_name = { "value1", "value2", ... }
...
}
..
.. js:attribute:: Reply.body
The reply payload.
:returns: string
.. js:function:: Reply.set_status(REPLY, status[, reason])
Set the reply status code and optionally the reason-phrase. If the reason is
not provided, the default reason corresponding to the status code is used.
:param class_reply reply: The related Reply object.
:param integer status: The reply status code.
:param string reason: The reply status reason (optional).
.. js:function:: Reply.add_header(REPLY, name, value)
Add a header to the reply object. If the header does not already exist, a new
entry is created with its name as index and a one-element list containing its
value as value. Otherwise, the header value is appended to the ordered list of
values associated to the header name.
:param class_reply reply: The related Reply object.
:param string name: The header field name.
:param string value: The header field value.
.. js:function:: Reply.del_header(REPLY, name)
Remove all occurrences of a header name from the reply object.
:param class_reply reply: The related Reply object.
:param string name: The header field name.
.. js:function:: Reply.set_body(REPLY, body)
Set the reply payload.
:param class_reply reply: The related Reply object.
:param string body: The reply payload.
.. _socket_class:
Socket class
============
.. js:class:: Socket
This class must be compatible with the Lua Socket class. Only the 'client'
functions are available. See the Lua Socket documentation:
`http://w3.impa.br/~diego/software/luasocket/tcp.html
<http://w3.impa.br/~diego/software/luasocket/tcp.html>`_
.. js:function:: Socket.close(socket)
Closes a TCP object. The internal socket used by the object is closed and the
local address to which the object was bound is made available to other
applications. No further operations (except for further calls to the close
method) are allowed on a closed Socket.
:param class_socket socket: Is the manipulated Socket.
Note: It is important to close all used sockets once they are not needed,
since, in many systems, each socket uses a file descriptor, which are limited
system resources. Garbage-collected objects are automatically closed before
destruction, though.
.. js:function:: Socket.connect(socket, address[, port])
Attempts to connect a socket object to a remote host.
In case of error, the method returns nil followed by a string describing the
error. In case of success, the method returns 1.
:param class_socket socket: Is the manipulated Socket.
:param string address: can be an IP address or a host name. See below for more
information.
:param integer port: must be an integer number in the range [1..64K].
:returns: 1 or nil.
An address field extension permits to use the connect() function to connect to
other stream than TCP. The syntax containing a simpleipv4 or ipv6 address is
the basically expected format. This format requires the port.
Other format accepted are a socket path like "/socket/path", it permits to
connect to a socket. Abstract namespaces are supported with the prefix
"abns@", and finally a file descriptor can be passed with the prefix "fd@".
The prefix "ipv4@", "ipv6@" and "unix@" are also supported. The port can be
passed int the string. The syntax "127.0.0.1:1234" is valid. In this case, the
parameter *port* must not be set.
.. js:function:: Socket.connect_ssl(socket, address, port)
Same behavior than the function socket:connect, but uses SSL.
:param class_socket socket: Is the manipulated Socket.
:returns: 1 or nil.
.. js:function:: Socket.getpeername(socket)
Returns information about the remote side of a connected client object.
Returns a string with the IP address of the peer, followed by the port number
that peer is using for the connection. In case of error, the method returns
nil.
:param class_socket socket: Is the manipulated Socket.
:returns: a string containing the server information.
.. js:function:: Socket.getsockname(socket)
Returns the local address information associated to the object.
The method returns a string with local IP address and a number with the port.
In case of error, the method returns nil.
:param class_socket socket: Is the manipulated Socket.
:returns: a string containing the client information.
.. js:function:: Socket.receive(socket, [pattern [, prefix]])
Reads data from a client object, according to the specified read pattern.
Patterns follow the Lua file I/O format, and the difference in performance
between all patterns is negligible.
:param class_socket socket: Is the manipulated Socket.
:param string|integer pattern: Describe what is required (see below).
:param string prefix: A string which will be prefix the returned data.
:returns: a string containing the required data or nil.
Pattern can be any of the following:
* **`*a`**: reads from the socket until the connection is closed. No
end-of-line translation is performed;
* **`*l`**: reads a line of text from the Socket. The line is terminated by a
LF character (ASCII 10), optionally preceded by a CR character
(ASCII 13). The CR and LF characters are not included in the
returned line. In fact, all CR characters are ignored by the
pattern. This is the default pattern.
* **number**: causes the method to read a specified number of bytes from the
Socket. Prefix is an optional string to be concatenated to the
beginning of any received data before return.
* **empty**: If the pattern is left empty, the default option is `*l`.
If successful, the method returns the received pattern. In case of error, the
method returns nil followed by an error message which can be the string
'closed' in case the connection was closed before the transmission was
completed or the string 'timeout' in case there was a timeout during the
operation. Also, after the error message, the function returns the partial
result of the transmission.
Important note: This function was changed severely. It used to support
multiple patterns (but I have never seen this feature used) and now it
doesn't anymore. Partial results used to be returned in the same way as
successful results. This last feature violated the idea that all functions
should return nil on error. Thus it was changed too.
.. js:function:: Socket.send(socket, data [, start [, end ]])
Sends data through client object.
:param class_socket socket: Is the manipulated Socket.
:param string data: The data that will be sent.
:param integer start: The start position in the buffer of the data which will
be sent.
:param integer end: The end position in the buffer of the data which will
be sent.
:returns: see below.
Data is the string to be sent. The optional arguments i and j work exactly
like the standard string.sub Lua function to allow the selection of a
substring to be sent.
If successful, the method returns the index of the last byte within [start,
end] that has been sent. Notice that, if start is 1 or absent, this is
effectively the total number of bytes sent. In case of error, the method
returns nil, followed by an error message, followed by the index of the last
byte within [start, end] that has been sent. You might want to try again from
the byte following that. The error message can be 'closed' in case the
connection was closed before the transmission was completed or the string
'timeout' in case there was a timeout during the operation.
Note: Output is not buffered. For small strings, it is always better to
concatenate them in Lua (with the '..' operator) and send the result in one
call instead of calling the method several times.
.. js:function:: Socket.setoption(socket, option [, value])
Just implemented for compatibility, this cal does nothing.
.. js:function:: Socket.settimeout(socket, value [, mode])
Changes the timeout values for the object. All I/O operations are blocking.
That is, any call to the methods send, receive, and accept will block
indefinitely, until the operation completes. The settimeout method defines a
limit on the amount of time the I/O methods can block. When a timeout time
has elapsed, the affected methods give up and fail with an error code.
The amount of time to wait is specified as the value parameter, in seconds.
The timeout modes are not implemented, the only settable timeout is the
inactivity time waiting for complete the internal buffer send or waiting for
receive data.
:param class_socket socket: Is the manipulated Socket.
:param float value: The timeout value. Use floating point to specify
milliseconds.
.. _regex_class:
Regex class
===========
.. js:class:: Regex
This class allows the usage of HAProxy regexes because classic lua doesn't
provides regexes. This class inherits the HAProxy compilation options, so the
regexes can be libc regex, pcre regex or pcre JIT regex.
The expression matching number is limited to 20 per regex. The only available
option is case sensitive.
Because regexes compilation is a heavy process, it is better to define all
your regexes in the **body context** and use it during the runtime.
.. code-block:: lua
-- Create the regex
st, regex = Regex.new("needle (..) (...)", true);
-- Check compilation errors
if st == false then
print "error: " .. regex
end
-- Match the regexes
print(regex:exec("Looking for a needle in the haystack")) -- true
print(regex:exec("Lokking for a cat in the haystack")) -- false
-- Extract words
st, list = regex:match("Looking for a needle in the haystack")
print(st) -- true
print(list[1]) -- needle in the
print(list[2]) -- in
print(list[3]) -- the
.. js:function:: Regex.new(regex, case_sensitive)
Create and compile a regex.
:param string regex: The regular expression according with the libc or pcre
standard
:param boolean case_sensitive: Match is case sensitive or not.
:returns: boolean status and :ref:`regex_class` or string containing fail reason.
.. js:function:: Regex.exec(regex, str)
Execute the regex.
:param class_regex regex: A :ref:`regex_class` object.
:param string str: The input string will be compared with the compiled regex.
:returns: a boolean status according with the match result.
.. js:function:: Regex.match(regex, str)
Execute the regex and return matched expressions.
:param class_map map: A :ref:`regex_class` object.
:param string str: The input string will be compared with the compiled regex.
:returns: a boolean status according with the match result, and
a table containing all the string matched in order of declaration.
.. _map_class:
Map class
=========
.. js:class:: Map
This class permits to do some lookup in HAProxy maps. The declared maps can
be modified during the runtime through the HAProxy management socket.
.. code-block:: lua
default = "usa"
-- Create and load map
geo = Map.new("geo.map", Map._ip);
-- Create new fetch that returns the user country
core.register_fetches("country", function(txn)
local src;
local loc;
src = txn.f:fhdr("x-forwarded-for");
if (src == nil) then
src = txn.f:src()
if (src == nil) then
return default;
end
end
-- Perform lookup
loc = geo:lookup(src);
if (loc == nil) then
return default;
end
return loc;
end);
.. js:attribute:: Map._int
See the HAProxy configuration.txt file, chapter "Using ACLs and fetching
samples" and subchapter "ACL basics" to understand this pattern matching
method.
Note that :js:attr:`Map.int` is also available for compatibility.
.. js:attribute:: Map._ip
See the HAProxy configuration.txt file, chapter "Using ACLs and fetching
samples" and subchapter "ACL basics" to understand this pattern matching
method.
Note that :js:attr:`Map.ip` is also available for compatibility.
.. js:attribute:: Map._str
See the HAProxy configuration.txt file, chapter "Using ACLs and fetching
samples" and subchapter "ACL basics" to understand this pattern matching
method.
Note that :js:attr:`Map.str` is also available for compatibility.
.. js:attribute:: Map._beg
See the HAProxy configuration.txt file, chapter "Using ACLs and fetching
samples" and subchapter "ACL basics" to understand this pattern matching
method.
Note that :js:attr:`Map.beg` is also available for compatibility.
.. js:attribute:: Map._sub
See the HAProxy configuration.txt file, chapter "Using ACLs and fetching
samples" and subchapter "ACL basics" to understand this pattern matching
method.
Note that :js:attr:`Map.sub` is also available for compatibility.
.. js:attribute:: Map._dir
See the HAProxy configuration.txt file, chapter "Using ACLs and fetching
samples" and subchapter "ACL basics" to understand this pattern matching
method.
Note that :js:attr:`Map.dir` is also available for compatibility.
.. js:attribute:: Map._dom
See the HAProxy configuration.txt file, chapter "Using ACLs and fetching
samples" and subchapter "ACL basics" to understand this pattern matching
method.
Note that :js:attr:`Map.dom` is also available for compatibility.
.. js:attribute:: Map._end
See the HAProxy configuration.txt file, chapter "Using ACLs and fetching
samples" and subchapter "ACL basics" to understand this pattern matching
method.
.. js:attribute:: Map._reg
See the HAProxy configuration.txt file, chapter "Using ACLs and fetching
samples" and subchapter "ACL basics" to understand this pattern matching
method.
Note that :js:attr:`Map.reg` is also available for compatibility.
.. js:function:: Map.new(file, method)
Creates and load a map.
:param string file: Is the file containing the map.
:param integer method: Is the map pattern matching method. See the attributes
of the Map class.
:returns: a class Map object.
:see: The Map attributes: :js:attr:`Map._int`, :js:attr:`Map._ip`,
:js:attr:`Map._str`, :js:attr:`Map._beg`, :js:attr:`Map._sub`,
:js:attr:`Map._dir`, :js:attr:`Map._dom`, :js:attr:`Map._end` and
:js:attr:`Map._reg`.
.. js:function:: Map.lookup(map, str)
Perform a lookup in a map.
:param class_map map: Is the class Map object.
:param string str: Is the string used as key.
:returns: a string containing the result or nil if no match.
.. js:function:: Map.slookup(map, str)
Perform a lookup in a map.
:param class_map map: Is the class Map object.
:param string str: Is the string used as key.
:returns: a string containing the result or empty string if no match.
.. _applethttp_class:
AppletHTTP class
================
.. js:class:: AppletHTTP
This class is used with applets that requires the 'http' mode. The http applet
can be registered with the *core.register_service()* function. They are used
for processing an http request like a server in back of HAProxy.
This is an hello world sample code:
.. code-block:: lua
core.register_service("hello-world", "http", function(applet)
local response = "Hello World !"
applet:set_status(200)
applet:add_header("content-length", string.len(response))
applet:add_header("content-type", "text/plain")
applet:start_response()
applet:send(response)
end)
.. js:attribute:: AppletHTTP.c
:returns: A :ref:`converters_class`
This attribute contains a Converters class object.
.. js:attribute:: AppletHTTP.sc
:returns: A :ref:`converters_class`
This attribute contains a Converters class object. The
functions of this object returns always a string.
.. js:attribute:: AppletHTTP.f
:returns: A :ref:`fetches_class`
This attribute contains a Fetches class object. Note that the
applet execution place cannot access to a valid HAProxy core HTTP
transaction, so some sample fetches related to the HTTP dependent
values (hdr, path, ...) are not available.
.. js:attribute:: AppletHTTP.sf
:returns: A :ref:`fetches_class`
This attribute contains a Fetches class object. The functions of
this object returns always a string. Note that the applet
execution place cannot access to a valid HAProxy core HTTP
transaction, so some sample fetches related to the HTTP dependent
values (hdr, path, ...) are not available.
.. js:attribute:: AppletHTTP.method
:returns: string
The attribute method returns a string containing the HTTP
method.
.. js:attribute:: AppletHTTP.version
:returns: string
The attribute version, returns a string containing the HTTP
request version.
.. js:attribute:: AppletHTTP.path
:returns: string
The attribute path returns a string containing the HTTP
request path.
.. js:attribute:: AppletHTTP.qs
:returns: string
The attribute qs returns a string containing the HTTP
request query string.
.. js:attribute:: AppletHTTP.length
:returns: integer
The attribute length returns an integer containing the HTTP
body length.
.. js:attribute:: AppletHTTP.headers
:returns: table
The attribute headers returns a table containing the HTTP
headers. The header names are always in lower case. As the header name can be
encountered more than once in each request, the value is indexed with 0 as
first index value. The table have this form:
.. code-block:: lua
AppletHTTP.headers['<header-name>'][<header-index>] = "<header-value>"
AppletHTTP.headers["host"][0] = "www.test.com"
AppletHTTP.headers["accept"][0] = "audio/basic q=1"
AppletHTTP.headers["accept"][1] = "audio/*, q=0.2"
AppletHTTP.headers["accept"][2] = "*/*, q=0.1"
..
.. js:function:: AppletHTTP.set_status(applet, code [, reason])
This function sets the HTTP status code for the response. The allowed code are
from 100 to 599.
:param class_AppletHTTP applet: An :ref:`applethttp_class`
:param integer code: the status code returned to the client.
:param string reason: the status reason returned to the client (optional).
.. js:function:: AppletHTTP.add_header(applet, name, value)
This function add an header in the response. Duplicated headers are not
collapsed. The special header *content-length* is used to determinate the
response length. If it not exists, a *transfer-encoding: chunked* is set, and
all the write from the function *AppletHTTP:send()* become a chunk.
:param class_AppletHTTP applet: An :ref:`applethttp_class`
:param string name: the header name
:param string value: the header value
.. js:function:: AppletHTTP.start_response(applet)
This function indicates to the HTTP engine that it can process and send the
response headers. After this called we cannot add headers to the response; We
cannot use the *AppletHTTP:send()* function if the
*AppletHTTP:start_response()* is not called.
:param class_AppletHTTP applet: An :ref:`applethttp_class`
.. js:function:: AppletHTTP.getline(applet)
This function returns a string containing one line from the http body. If the
data returned doesn't contains a final '\\n' its assumed than its the last
available data before the end of stream.
:param class_AppletHTTP applet: An :ref:`applethttp_class`
:returns: a string. The string can be empty if we reach the end of the stream.
.. js:function:: AppletHTTP.receive(applet, [size])
Reads data from the HTTP body, according to the specified read *size*. If the
*size* is missing, the function tries to read all the content of the stream
until the end. If the *size* is bigger than the http body, it returns the
amount of data available.
:param class_AppletHTTP applet: An :ref:`applethttp_class`
:param integer size: the required read size.
:returns: always return a string,the string can be empty is the connection is
closed.
.. js:function:: AppletHTTP.send(applet, msg)
Send the message *msg* on the http request body.
:param class_AppletHTTP applet: An :ref:`applethttp_class`
:param string msg: the message to send.
.. js:function:: AppletHTTP.get_priv(applet)
Return Lua data stored in the current transaction. If no data are stored,
it returns a nil value.
:param class_AppletHTTP applet: An :ref:`applethttp_class`
:returns: the opaque data previously stored, or nil if nothing is
available.
:see: :js:func:`AppletHTTP.set_priv`
.. js:function:: AppletHTTP.set_priv(applet, data)
Store any data in the current HAProxy transaction. This action replace the
old stored data.
:param class_AppletHTTP applet: An :ref:`applethttp_class`
:param opaque data: The data which is stored in the transaction.
:see: :js:func:`AppletHTTP.get_priv`
.. js:function:: AppletHTTP.set_var(applet, var, value[, ifexist])
Converts a Lua type in a HAProxy type and store it in a variable <var>.
:param class_AppletHTTP applet: An :ref:`applethttp_class`
:param string var: The variable name according with the HAProxy variable syntax.
:param type value: The value associated to the variable. The type ca be string or
integer.
:param boolean ifexist: If this parameter is set to a truthy value the variable
will only be set if it was defined elsewhere (i.e. used
within the configuration). It is highly recommended to
always set this to true.
:see: :js:func:`AppletHTTP.unset_var`
:see: :js:func:`AppletHTTP.get_var`
.. js:function:: AppletHTTP.unset_var(applet, var)
Unset the variable <var>.
:param class_AppletHTTP applet: An :ref:`applethttp_class`
:param string var: The variable name according with the HAProxy variable syntax.
:see: :js:func:`AppletHTTP.set_var`
:see: :js:func:`AppletHTTP.get_var`
.. js:function:: AppletHTTP.get_var(applet, var)
Returns data stored in the variable <var> converter in Lua type.
:param class_AppletHTTP applet: An :ref:`applethttp_class`
:param string var: The variable name according with the HAProxy variable syntax.
:see: :js:func:`AppletHTTP.set_var`
:see: :js:func:`AppletHTTP.unset_var`
.. _applettcp_class:
AppletTCP class
===============
.. js:class:: AppletTCP
This class is used with applets that requires the 'tcp' mode. The tcp applet
can be registered with the *core.register_service()* function. They are used
for processing a tcp stream like a server in back of HAProxy.
.. js:attribute:: AppletTCP.c
:returns: A :ref:`converters_class`
This attribute contains a Converters class object.
.. js:attribute:: AppletTCP.sc
:returns: A :ref:`converters_class`
This attribute contains a Converters class object. The
functions of this object returns always a string.
.. js:attribute:: AppletTCP.f
:returns: A :ref:`fetches_class`
This attribute contains a Fetches class object.
.. js:attribute:: AppletTCP.sf
:returns: A :ref:`fetches_class`
This attribute contains a Fetches class object.
.. js:function:: AppletTCP.getline(applet)
This function returns a string containing one line from the stream. If the
data returned doesn't contains a final '\\n' its assumed than its the last
available data before the end of stream.
:param class_AppletTCP applet: An :ref:`applettcp_class`
:returns: a string. The string can be empty if we reach the end of the stream.
.. js:function:: AppletTCP.receive(applet, [size])
Reads data from the TCP stream, according to the specified read *size*. If the
*size* is missing, the function tries to read all the content of the stream
until the end.
:param class_AppletTCP applet: An :ref:`applettcp_class`
:param integer size: the required read size.
:returns: always return a string,the string can be empty is the connection is
closed.
.. js:function:: AppletTCP.send(appletmsg)
Send the message on the stream.
:param class_AppletTCP applet: An :ref:`applettcp_class`
:param string msg: the message to send.
.. js:function:: AppletTCP.get_priv(applet)
Return Lua data stored in the current transaction. If no data are stored,
it returns a nil value.
:param class_AppletTCP applet: An :ref:`applettcp_class`
:returns: the opaque data previously stored, or nil if nothing is
available.
:see: :js:func:`AppletTCP.set_priv`
.. js:function:: AppletTCP.set_priv(applet, data)
Store any data in the current HAProxy transaction. This action replace the
old stored data.
:param class_AppletTCP applet: An :ref:`applettcp_class`
:param opaque data: The data which is stored in the transaction.
:see: :js:func:`AppletTCP.get_priv`
.. js:function:: AppletTCP.set_var(applet, var, value[, ifexist])
Converts a Lua type in a HAProxy type and stores it in a variable <var>.
:param class_AppletTCP applet: An :ref:`applettcp_class`
:param string var: The variable name according with the HAProxy variable syntax.
:param type value: The value associated to the variable. The type can be string or
integer.
:param boolean ifexist: If this parameter is set to a truthy value the variable
will only be set if it was defined elsewhere (i.e. used
within the configuration). It is highly recommended to
always set this to true.
:see: :js:func:`AppletTCP.unset_var`
:see: :js:func:`AppletTCP.get_var`
.. js:function:: AppletTCP.unset_var(applet, var)
Unsets the variable <var>.
:param class_AppletTCP applet: An :ref:`applettcp_class`
:param string var: The variable name according with the HAProxy variable syntax.
:see: :js:func:`AppletTCP.unset_var`
:see: :js:func:`AppletTCP.set_var`
.. js:function:: AppletTCP.get_var(applet, var)
Returns data stored in the variable <var> converter in Lua type.
:param class_AppletTCP applet: An :ref:`applettcp_class`
:param string var: The variable name according with the HAProxy variable syntax.
:see: :js:func:`AppletTCP.unset_var`
:see: :js:func:`AppletTCP.set_var`
StickTable class
================
.. js:class:: StickTable
**context**: task, action, sample-fetch
This class can be used to access the HAProxy stick tables from Lua.
.. js:function:: StickTable.info()
Returns stick table attributes as a Lua table. See HAProxy documentation for
"stick-table" for canonical info, or check out example below.
:returns: Lua table
Assume our table has IPv4 key and gpc0 and conn_rate "columns":
.. code-block:: lua
{
expire=<int>, # Value in ms
size=<int>, # Maximum table size
used=<int>, # Actual number of entries in table
data={ # Data columns, with types as key, and periods as values
(-1 if type is not rate counter)
conn_rate=<int>,
gpc0=-1
},
length=<int>, # max string length for string table keys, key length
# otherwise
nopurge=<boolean>, # purge oldest entries when table is full
type="ip" # can be "ip", "ipv6", "integer", "string", "binary"
}
.. js:function:: StickTable.lookup(key)
Returns stick table entry for given <key>
:param string key: Stick table key (IP addresses and strings are supported)
:returns: Lua table
.. js:function:: StickTable.dump([filter])
Returns all entries in stick table. An optional filter can be used
to extract entries with specific data values. Filter is a table with valid
comparison operators as keys followed by data type name and value pairs.
Check out the HAProxy docs for "show table" for more details. For the
reference, the supported operators are:
"eq", "ne", "le", "lt", "ge", "gt"
For large tables, execution of this function can take a long time (for
HAProxy standards). That's also true when filter is used, so take care and
measure the impact.
:param table filter: Stick table filter
:returns: Stick table entries (table)
See below for example filter, which contains 4 entries (or comparisons).
(Maximum number of filter entries is 4, defined in the source code)
.. code-block:: lua
local filter = {
{"gpc0", "gt", 30}, {"gpc1", "gt", 20}}, {"conn_rate", "le", 10}
}
.. _action_class:
Action class
=============
.. js:class:: Act
**context**: action
This class contains all return codes an action may return. It is the lua
equivalent to HAProxy "ACT_RET_*" code.
.. code-block:: lua
core.register_action("deny", { "http-req" }, function (txn)
return act.DENY
end)
..
.. js:attribute:: act.CONTINUE
This attribute is an integer (0). It instructs HAProxy to continue the current
ruleset processing on the message. It is the default return code for a lua
action.
:returns: integer
.. js:attribute:: act.STOP
This attribute is an integer (1). It instructs HAProxy to stop the current
ruleset processing on the message.
.. js:attribute:: act.YIELD
This attribute is an integer (2). It instructs HAProxy to temporarily pause
the message processing. It will be resumed later on the same rule. The
corresponding lua script is re-executed for the start.
.. js:attribute:: act.ERROR
This attribute is an integer (3). It triggers an internal errors The message
processing is stopped and the transaction is terminated. For HTTP streams, an
HTTP 500 error is returned to the client.
:returns: integer
.. js:attribute:: act.DONE
This attribute is an integer (4). It instructs HAProxy to stop the message
processing.
:returns: integer
.. js:attribute:: act.DENY
This attribute is an integer (5). It denies the current message. The message
processing is stopped and the transaction is terminated. For HTTP streams, an
HTTP 403 error is returned to the client if the deny is returned during the
request analysis. During the response analysis, an HTTP 502 error is returned
and the server response is discarded.
:returns: integer
.. js:attribute:: act.ABORT
This attribute is an integer (6). It aborts the current message. The message
processing is stopped and the transaction is terminated. For HTTP streams,
HAProxy assumes a response was already sent to the client. From the Lua
actions point of view, when this code is used, the transaction is terminated
with no reply.
:returns: integer
.. js:attribute:: act.INVALID
This attribute is an integer (7). It triggers an internal errors. The message
processing is stopped and the transaction is terminated. For HTTP streams, an
HTTP 400 error is returned to the client if the error is returned during the
request analysis. During the response analysis, an HTTP 502 error is returned
and the server response is discarded.
:returns: integer
.. js:function:: act:wake_time(milliseconds)
**context**: action
Set the script pause timeout to the specified time, defined in
milliseconds.
:param integer milliseconds: the required milliseconds.
This function may be used when a lua action returns `act.YIELD`, to force its
wake-up at most after the specified number of milliseconds.
External Lua libraries
======================
A lot of useful lua libraries can be found here:
* `https://lua-toolbox.com/ <https://lua-toolbox.com/>`_
Redis client library:
* `https://github.com/nrk/redis-lua <https://github.com/nrk/redis-lua>`_
This is an example about the usage of the Redis library with HAProxy. Note that
each call of any function of this library can throw an error if the socket
connection fails.
.. code-block:: lua
-- load the redis library
local redis = require("redis");
function do_something(txn)
-- create and connect new tcp socket
local tcp = core.tcp();
tcp:settimeout(1);
tcp:connect("127.0.0.1", 6379);
-- use the redis library with this new socket
local client = redis.connect({socket=tcp});
client:ping();
end
OpenSSL:
* `http://mkottman.github.io/luacrypto/index.html
<http://mkottman.github.io/luacrypto/index.html>`_
* `https://github.com/brunoos/luasec/wiki
<https://github.com/brunoos/luasec/wiki>`_