From: Pierre Cheynier <p.cheynier@criteo.com>
Date: Fri, 17 Apr 2026 07:37:14 +0000 (+0000)
Subject: MINOR: sample: converter for frontend existence check
X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=85c3f3c1fd0003bc972f61dbf23a25cf9ed93ef6;p=thirdparty%2Fhaproxy.git

MINOR: sample: converter for frontend existence check

Introduced a new sample converter using keyword "fe_exists" checking if
a frontend with a given name exists.
---

diff --git a/doc/configuration.txt b/doc/configuration.txt
index 3ddd176f1..461c07b40 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -21018,6 +21018,7 @@ eth.proto                                          binary       integer
 eth.src                                            binary       binary
 eth.vlan                                           binary       integer
 even                                               integer      boolean
+fe_exists                                          string       boolean
 field(index,delimiters[,count])                    string       string
 fix_is_valid                                       binary       boolean
 fix_tag_value(tag)                                 binary       binary
@@ -21548,6 +21549,15 @@ field(<index>,<delimiters>[,<count>])
       str(f1_f2_f3__f5),field(-2,_,3) # f2_f3_
       str(f1_f2_f3__f5),field(-3,_,0) # f1_f2_f3
 
+fe_exists
+  Takes a frontend name as input value and returns a boolean TRUE if the said
+  frontend with that name exists in the current configuration, otherwise returns
+  FALSE. Can be used in places where checking the existence of a frontend from a
+  dynamic name is valuable, like map lookups or answering to an external check.
+
+  Example :
+      http-request deny unless { var(txn.fe_name),fe_exists }
+
 fix_is_valid
   Parses a binary payload and performs sanity checks regarding FIX (Financial
   Information eXchange):
diff --git a/src/frontend.c b/src/frontend.c
index 383878212..79acbb00f 100644
--- a/src/frontend.c
+++ b/src/frontend.c
@@ -326,6 +326,16 @@ smp_fetch_fe_tarpit_timeout(const struct arg *args, struct sample *smp, const ch
 	return 1;
 }
 
+static int
+sample_conv_fe_exists(const struct arg *args, struct sample *smp, void *private)
+{
+	if (!smp_make_safe(smp))
+		return 0;
+
+	smp->data.type = SMP_T_BOOL;
+	smp->data.u.sint = proxy_fe_by_name(smp->data.u.str.area) != NULL;
+	return 1;
+}
 
 /* Note: must not be declared <const> as its list will be overwritten.
  * Please take care of keeping this list alphabetically sorted.
@@ -344,6 +354,14 @@ static struct sample_fetch_kw_list smp_kws = {ILH, {
 
 INITCALL1(STG_REGISTER, sample_register_fetches, &smp_kws);
 
+/* Note: must not be declared <const> as its list will be overwritten */
+static struct sample_conv_kw_list sample_conv_kws = {ILH, {
+	{ "fe_exists", sample_conv_fe_exists, 0, NULL, SMP_T_STR, SMP_T_BOOL },
+	{ /* END */ },
+}};
+
+INITCALL1(STG_REGISTER, sample_register_convs, &sample_conv_kws);
+
 /* Note: must not be declared <const> as its list will be overwritten.
  * Please take care of keeping this list alphabetically sorted.
  */