From d622f9d5b6c391fa650786a07c7d4eb23b3cd5b1 Mon Sep 17 00:00:00 2001
From: Aurelien DARRAGON <adarragon@haproxy.com>
Date: Mon, 23 Sep 2024 12:05:18 +0200
Subject: [PATCH] MEDIUM: mailers: warn about deprecated legacy mailers

As mentioned in 2.8 announce on the mailing list [1] and on the wiki [2],
use of legacy mailers is now deprecated and will not be supported anymore
starting with version 3.3. Use of Lua script (AKA Lua mailers) is now
encouraged (and fully supported since 2.8) for this purpose, as it offers
more flexibility (e.g: alerts can be customized) and is more future-proof.

Configurations relying on legacy mailers will now raise a warning.

Users willing to keep their existing mailers config in a working state
should simply add the following line to their global section:

   # mailers.lua file as provided in the git repository
   # adjust path as needed
   lua-load examples/lua/mailers.lua

[1]: https://www.mail-archive.com/haproxy@formilux.org/msg43600.html
[2]: https://github.com/haproxy/wiki/wiki/Breaking-changes
---
 doc/configuration.txt | 8 +++++++-
 src/mailers.c         | 6 +++++-
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/doc/configuration.txt b/doc/configuration.txt
index 5054e9827..966bfbad0 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -4600,7 +4600,8 @@ table <tablename> type {ip | integer | string [len <length>] | binary [len <leng
 ------------
 It is possible to send email alerts when the state of servers changes.
 If configured email alerts are sent to each mailer that is configured
-in a mailers section. Email is sent to mailers using SMTP.
+in a mailers section. Email is sent to mailers through Lua (see
+examples/lua/mailers.lua).
 
 mailers <mailersect>
   Creates a new mailer list with the name <mailersect>. It is an
@@ -4610,6 +4611,11 @@ mailer <mailername> <ip>:<port>
   Defines a mailer inside a mailers section.
 
   Example:
+    global
+        # mailers.lua file as provided in the git repository
+        # adjust path as needed
+        lua-load examples/lua/mailers.lua
+
     mailers mymailers
         mailer smtp1 192.168.0.1:587
         mailer smtp2 192.168.0.2:587
diff --git a/src/mailers.c b/src/mailers.c
index 905bb6745..50f1e76d3 100644
--- a/src/mailers.c
+++ b/src/mailers.c
@@ -20,7 +20,7 @@
 #include <haproxy/list.h>
 #include <haproxy/mailers.h>
 #include <haproxy/pool.h>
-#include <haproxy/proxy-t.h>
+#include <haproxy/proxy.h>
 #include <haproxy/server-t.h>
 #include <haproxy/task.h>
 #include <haproxy/tcpcheck.h>
@@ -113,6 +113,10 @@ int init_email_alert(struct mailers *mls, struct proxy *p, char **err)
 	const char          *err_str;
 	int                  i = 0;
 
+	if (!send_email_disabled)
+		ha_warning("Legacy mailers used by %s '%s' will not be supported anymore in version 3.3. You should use Lua to send email-alerts, see 'examples/lua/mailers.lua' file.\n",
+			   proxy_type_str(p), p->id);
+
 	if ((queues = calloc(mls->count, sizeof(*queues))) == NULL) {
 		memprintf(err, "out of memory while allocating mailer alerts queues");
 		goto fail_no_queue;