EXAMPLES: mailqueue for lua mailers script
Lua mailers scripts now leverages Queue class to implement a mailqueue.
Thanks to the mailqueue, emails are still sent asynchronously, but with
respect to their generation order (better ordering consistency).
That is, previous script limitation (see below) is no longer true:
"
Current known script limitation: if multiple events are generated
simultaneously it is possible that emails could be received out of
order since emails are sent asynchronously using smtp_send_email()
and there is no sending queue. Relying on the email "date" should
help to know which email was generated first..
"
For a given server, email-alerts will be sent in the same order as the
events were generated. However this does not apply to events between 2
distinct servers, since each server is tracked independently within
the lua script. (1 subscription per server, to make sure only relevant
servers x events are being tracked and prevent useless wakeups)
diff --git a/examples/lua/mailers.lua b/examples/lua/mailers.lua
index cbc8205..e36800b 100644
--- a/examples/lua/mailers.lua
+++ b/examples/lua/mailers.lua
@@ -16,6 +16,8 @@
["DEBUG"] = 7
}
+local mailqueue = core.queue()
+
-- smtp : send SMTP message
--
-- Copyright 2018 Thierry Fournier
@@ -140,28 +142,16 @@
return
end
- -- email sending is performed asynchronously
- core.register_task(function(mailers, msg, when)
- for name, mailsrv in pairs(mailers.mailservers) do
- local mailsrv_ip, mailsrv_port = string.match(mailsrv, "([^:]+):([^:]+)")
- local date = os.date("%a, %d %b %Y %T %z (%Z)", when)
- local c = core.concat()
+ -- email sending is performed asynchronously thanks to mailqueue
+ local job = {}
- c:add(string.format("From: %s\r\n", mailers.smtp_from))
- c:add(string.format("To: %s\r\n", mailers.smtp_to))
- c:add(string.format("Date: %s\r\n", date))
- c:add(string.format("Subject: [HAProxy Alert] %s\r\n", msg))
- c:add("\r\n")
- c:add(string.format("%s\r\n", msg))
+ job.mailconf = mailers
+ job.when = when
+ job.msg = message
- local ret, reason = smtp_send_email(mailsrv_ip, mailsrv_port,
- mailers.smtp_hostname, mailers.smtp_from,
- mailers.smtp_to, c:dump())
- if ret == false then
- core.Warning("Can't send email: " .. reason)
- end
- end
- end, mailers, message, when)
+ -- enqueue email job
+ mailqueue:push(job)
+
end
local function srv_get_check_details(check)
@@ -388,4 +378,41 @@
end
end
+end)
+
+-- mail queue
+core.register_task(function()
+ while true
+ do
+ local job = mailqueue:pop_wait()
+
+ if job ~= nil then
+ local date = os.date("%a, %d %b %Y %T %z (%Z)", job.when)
+ local c = core.concat()
+
+ -- prepare email body
+ c:add(string.format("From: %s\r\n", job.mailconf.smtp_from))
+ c:add(string.format("To: %s\r\n", job.mailconf.smtp_to))
+ c:add(string.format("Date: %s\r\n", date))
+ c:add(string.format("Subject: [HAProxy Alert] %s\r\n", job.msg))
+ c:add("\r\n")
+ c:add(string.format("%s\r\n", job.msg))
+
+ -- send email to all mailservers
+ for name, mailsrv in pairs(job.mailconf.mailservers) do
+ -- split mailsrv (ip:port) in 2 variables
+ local mailsrv_ip, mailsrv_port = string.match(mailsrv, "([^:]+):([^:]+)")
+
+ -- finally, send email to server
+ local ret, reason = smtp_send_email(mailsrv_ip, mailsrv_port,
+ job.mailconf.smtp_hostname,
+ job.mailconf.smtp_from,
+ job.mailconf.smtp_to,
+ c:dump())
+ if ret == false then
+ core.Warning("Can't send email alert to ".. name .. ": " .. reason)
+ end
+ end
+ end
+ end
end)