MEDIUM: proxy: Warn about ambiguous use of named defaults sections
It is now possible to designate the defaults section to use by adding a name
of the corresponding defaults section and referencing it in the desired
proxy section. However, this introduces an ambiguity. This named defaults
section may still be implicitly used by other proxies if it is the last one
defined. In this case for instance:
default common
...
default frt from common
...
default bck from common
...
frontend fe from frt
...
backend be from bck
...
listen stats
...
Here, it is not really obvious the last section will use the 'bck' defaults
section. And it is probably not the expected behaviour. To help users to
properly configure their haproxy, a warning is now emitted if a defaults
section is explicitly AND implicitly used. The configuration manual was
updated accordingly.
Because this patch adds a warning, it should probably not be backported to
2.4. However, if is is backported, it depends on commit "MINOR: proxy:
Introduce proxy flags to replace disabled bitfield".
diff --git a/doc/configuration.txt b/doc/configuration.txt
index 5884507..01cf319 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -3509,7 +3509,11 @@
names, and this name must be unique among the defaults sections. Please note
that regardless of what is currently permitted, it is recommended to avoid
duplicate section names in general and to respect the same syntax as for proxy
-names. This rule might be enforced in a future version.
+names. This rule might be enforced in a future version. In addition, a warning
+is emitted if a defaults section is explicitly used by a proxy while it is also
+implicitly used by another one because it is the last one defined. It is highly
+encouraged to not mix both usages by always using explicit references or by
+adding a last common defaults section reserved for all implicit uses.
Note that it is even possible for a defaults section to take its initial
settings from another one, and as such, inherit settings across multiple levels
diff --git a/include/haproxy/proxy-t.h b/include/haproxy/proxy-t.h
index c38c339..b2285bb 100644
--- a/include/haproxy/proxy-t.h
+++ b/include/haproxy/proxy-t.h
@@ -203,6 +203,8 @@
/* Proxy flags */
#define PR_FL_DISABLED 0x01 /* The proxy was disabled in the configuration (not at runtime) */
#define PR_FL_STOPPED 0x02 /* The proxy was stopped */
+#define PR_FL_EXPLICIT_REF 0x08 /* The default proxy is explicitly referenced by another proxy */
+#define PR_FL_IMPLICIT_REF 0x10 /* The default proxy is implicitly referenced by another proxy */
struct stream;
diff --git a/src/cfgparse-listen.c b/src/cfgparse-listen.c
index f6589d1..cd3f92b 100644
--- a/src/cfgparse-listen.c
+++ b/src/cfgparse-listen.c
@@ -316,6 +316,16 @@
file, linenum, *err, args[arg+1], curr_defproxy->conf.file, curr_defproxy->conf.line);
err_code |= ERR_ALERT | ERR_FATAL;
}
+ curr_defproxy->flags |= PR_FL_EXPLICIT_REF;
+ }
+ else if (curr_defproxy)
+ curr_defproxy->flags |= PR_FL_IMPLICIT_REF;
+
+ if (curr_defproxy && (curr_defproxy->flags & (PR_FL_EXPLICIT_REF|PR_FL_IMPLICIT_REF)) == (PR_FL_EXPLICIT_REF|PR_FL_IMPLICIT_REF)) {
+ ha_alert("parsing [%s:%d] : defaults section '%s' (declared at %s:%d) is explicitly referenced by another proxy and implicitly used here."
+ " To avoid any ambiguity don't mix both usage. Add a last defaults section not explicitly used or always use explicit references.\n",
+ file, linenum, curr_defproxy->id, curr_defproxy->conf.file, curr_defproxy->conf.line);
+ err_code |= ERR_WARN;
}
curproxy = parse_new_proxy(name, rc, file, linenum, curr_defproxy);