diff --git a/doc/configuration.txt b/doc/configuration.txt
index 583610f..f664175 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -1750,7 +1750,7 @@
   'set-var' action in TCP or HTTP rules except that the expression is evaluated
   at configuration parsing time and that the variable is instantly set. The
   sample fetch functions and converters permitted in the expression are only
-  those using internal data, typically 'int(value)' or 'str(value)'. It's is
+  those using internal data, typically 'int(value)' or 'str(value)'. It is
   possible to reference previously allocated variables as well. These variables
   will then be readable (and modifiable) from the regular rule sets.
 
@@ -1760,6 +1760,23 @@
           set-var proc.prio int(100)
           set-var proc.threshold int(200),sub(proc.prio)
 
+set-var-fmt <var-name> <fmt>
+  Sets the process-wide variable '<var-name>' to the string resulting from the
+  evaluation of the log-format <fmt>. The variable '<var-name>' may only be a
+  process-wide variable (using the 'proc.' prefix). It works exactly like the
+  'set-var-fmt' action in TCP or HTTP rules except that the expression is
+  evaluated at configuration parsing time and that the variable is instantly
+  set. The sample fetch functions and converters permitted in the expression
+  are only those using internal data, typically 'int(value)' or 'str(value)'.
+  It is possible to reference previously allocated variables as well. These
+  variables will then be readable (and modifiable) from the regular rule sets.
+  Please see section 8.2.4 for details on the log-format syntax.
+
+  Example:
+      global
+          set-var-fmt proc.current_state "primary"
+          set-var-fmt proc.bootid        "%pid|%t"
+
 setenv <name> <value>
   Sets environment variable <name> to value <value>. If the variable exists, it
   is overwritten. The changes immediately take effect so that the next line in
diff --git a/reg-tests/sample_fetches/vars.vtc b/reg-tests/sample_fetches/vars.vtc
index 95ab68d..82d7718 100644
--- a/reg-tests/sample_fetches/vars.vtc
+++ b/reg-tests/sample_fetches/vars.vtc
@@ -10,7 +10,7 @@
         set-var proc.str1  str("this is")
         set-var proc.str2  str("a string")
         set-var proc.str   var(proc.str1)
-        set-var proc.str   str(""),concat("",proc.str," a string")
+        set-var-fmt proc.str "%[var(proc.str)] a string"
         set-var proc.uuid  uuid()
 
     defaults
diff --git a/src/vars.c b/src/vars.c
index d4f4119..168ead6 100644
--- a/src/vars.c
+++ b/src/vars.c
@@ -12,6 +12,7 @@
 #include <haproxy/list.h>
 #include <haproxy/log.h>
 #include <haproxy/sample.h>
+#include <haproxy/session.h>
 #include <haproxy/stream-t.h>
 #include <haproxy/tcp_rules.h>
 #include <haproxy/tcpcheck.h>
@@ -894,6 +895,7 @@
  * expression that are parsed, processed, and released on the fly so that we
  * respect the real set-var syntax. These directives take the following format:
  *    set-var <name> <expression>
+ *    set-var-fmt <name> <fmt>
  * Note that parse_store() expects "set-var(name) <expression>" so we have to
  * temporarily replace the keyword here.
  */
@@ -910,21 +912,29 @@
 		.arg.vars.scope = SCOPE_PROC,
 		.from = ACT_F_CFG_PARSER,
 	};
+	enum obj_type objt = OBJ_TYPE_NONE;
+	struct session *sess = NULL;
 	enum act_parse_ret p_ret;
 	char *old_arg1;
 	char *tmp_arg1;
 	int arg = 2; // variable name
 	int ret = -1;
+	int use_fmt = 0;
 
 	LIST_INIT(&px.conf.args.list);
 
+	use_fmt = strcmp(args[0], "set-var-fmt") == 0;
+
 	if (!*args[1] || !*args[2]) {
-		memprintf(err, "'%s' requires a process-wide variable name ('proc.<name>') and a sample expression.", args[0]);
+		if (use_fmt)
+			memprintf(err, "'%s' requires a process-wide variable name ('proc.<name>') and a format string.", args[0]);
+		else
+			memprintf(err, "'%s' requires a process-wide variable name ('proc.<name>') and a sample expression.", args[0]);
 		goto end;
 	}
 
 	tmp_arg1 = NULL;
-	if (!memprintf(&tmp_arg1, "set-var(%s)", args[1]))
+	if (!memprintf(&tmp_arg1, "set-var%s(%s)", use_fmt ? "-fmt" : "", args[1]))
 		goto end;
 
 	/* parse_store() will always return a message in <err> on error */
@@ -946,8 +956,16 @@
 		goto end;
 	}
 
-	action_store(&rule, &px, NULL, NULL, 0);
+	if (use_fmt && !(sess = session_new(&px, NULL, &objt))) {
+		release_sample_expr(rule.arg.vars.expr);
+		memprintf(err, "'%s': out of memory when trying to set variable '%s' in the global section.", args[0], args[1]);
+		goto end;
+	}
+
+	action_store(&rule, &px, sess, NULL, 0);
 	release_sample_expr(rule.arg.vars.expr);
+	if (sess)
+		session_free(sess);
 
 	ret = 0;
  end:
@@ -1205,6 +1223,7 @@
 
 static struct cfg_kw_list cfg_kws = {{ },{
 	{ CFG_GLOBAL, "set-var",              vars_parse_global_set_var },
+	{ CFG_GLOBAL, "set-var-fmt",          vars_parse_global_set_var },
 	{ CFG_GLOBAL, "tune.vars.global-max-size", vars_max_size_global },
 	{ CFG_GLOBAL, "tune.vars.proc-max-size",   vars_max_size_proc   },
 	{ CFG_GLOBAL, "tune.vars.sess-max-size",   vars_max_size_sess   },