From: Amaury Denoyelle <adenoyelle@haproxy.com>
Date: Fri, 17 Jul 2026 08:19:36 +0000 (+0200)
Subject: MINOR: proxy: keep default-server unless empty setting
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=3f0736468586564cbc15a5b30fb308a2746ef7ef;p=thirdparty%2Fhaproxy.git

MINOR: proxy: keep default-server unless empty setting

Previously, default-server were removed as soon as a proxy section
parsing was over. This patch changes this behavior to now keep
default-server during haproxy runtime. This will allow to reuse them for
dynamic servers, which will be later implemented via "from" keyword as a
distinct feature.

Default-server may consume a noticeable amount of memory, so it can
still be desirable to clean up these elements on post-parsing. Thus, if
a default-server is reset, it will still be purged on section post
parsing. This can be achived by using a "default-server from none" final
line.

To detect if a default-server should be preserved, a new flag
SRV_F_UMODIFIED has been defined. Such flag is set as soon as a server
keyword has been parsed. It is reset when srv_settings_init() is used.
Thus, if this flag is present, default-server purge on post parsing is
skipped.
---

diff --git a/include/haproxy/server-t.h b/include/haproxy/server-t.h
index a7dfd6de0..6e6288a21 100644
--- a/include/haproxy/server-t.h
+++ b/include/haproxy/server-t.h
@@ -175,6 +175,7 @@ enum srv_init_state {
 #define SRV_F_CHK_NO_AUTO_SNI 0x20000    /* disable automatic SNI selection for healthcheck */
 #define SRV_F_UDP_GSO_NOTSUPP 0x40000    /* UDP GSO is disabled due to a previous error encountered */
 #define SRV_F_NAME_REFD    0x80000       /* this server's name is statically referenced (use-server, track, sample arg) */
+#define SRV_F_UMODIFIED    0x100000      /* at least one setting has been explicitely set via a server keyword */
 
 /* configured server options for send-proxy (server->pp_opts) */
 #define SRV_PP_V1               0x0001   /* proxy protocol version 1 */
diff --git a/src/proxy.c b/src/proxy.c
index 5d81c0918..9c80a636f 100644
--- a/src/proxy.c
+++ b/src/proxy.c
@@ -4321,13 +4321,13 @@ static int post_section_px_cleanup()
 {
 	if (!curproxy)
 		return 0; // nothing to do
-	if ((curproxy->cap & PR_CAP_LISTEN) && !(curproxy->cap & PR_CAP_DEF)) {
-		/* This is a regular proxy (not defaults). It doesn't need
-		 * to keep a default-server section if it still had one. We
-		 * want to keep it for defaults however, obviously.
-		 */
 
-		if (curproxy->defsrv) {
+	/* Perform clean up of empty default-server in proxies. This is not
+	 * executed for defaults section as this may still be useful.
+	 */
+	if ((curproxy->cap & PR_CAP_LISTEN) && !(curproxy->cap & PR_CAP_DEF)) {
+		/* Default-server is removed if it does not define specific setting. */
+		if (curproxy->defsrv && !(curproxy->defsrv->flags & SRV_F_UMODIFIED)) {
 			srv_free_params(curproxy->defsrv);
 			srv_free(&curproxy->defsrv);
 		}
diff --git a/src/server.c b/src/server.c
index 56639185f..d9140556f 100644
--- a/src/server.c
+++ b/src/server.c
@@ -2885,6 +2885,9 @@ int srv_prepare_for_resolution(struct server *srv, const char *hostname)
  */
 void srv_settings_init(struct server *srv)
 {
+	/* Mark server as reset. A default-server will be purged on post parsing. */
+	srv->flags &= ~SRV_F_UMODIFIED;
+
 	srv->check.inter = DEF_CHKINTR;
 	srv->check.fastinter = 0;
 	srv->check.downinter = 0;
@@ -4218,6 +4221,11 @@ int parse_server(const char *file, int linenum, char **args,
 		                         parse_flags);
 		if (err_code & ERR_FATAL)
 			goto out;
+
+		/* Mark server as modified by a keyword. Prevents a
+		 * default-server to be purged on post parsing.
+		 */
+		newsrv->flags |= SRV_F_UMODIFIED;
 	}
 
 	if (!(parse_flags & SRV_PARSE_DEFAULT_SERVER)) {