diff --git a/doc/configuration.txt b/doc/configuration.txt
index 59bf557..583610f 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -5282,7 +5282,7 @@
     http-response set-status 503 reason "Slow Down"
 
 http-after-response set-var(<var-name>) <expr> [ { if | unless } <condition> ]
-
+http-after-response set-var-fmt(<var-name>) <fmt> [ { if | unless } <condition> ]
   This is used to set the contents of a variable. The variable is declared
   inline.
 
@@ -5304,8 +5304,12 @@
     <expr>      Is a standard HAProxy expression formed by a sample-fetch
                 followed by some converters.
 
-  Example:
-    http-after-response set-var(sess.last_redir) res.hdr(location)
+    <fmt>       This is the value expressed using log-format rules (see Custom
+                Log Format in section 8.2.4).
+
+  Examples:
+       http-after-response set-var(sess.last_redir) res.hdr(location)
+       http-after-response set-var-fmt(sess.last_be_addr) %[bi]:%[bp]
 
 http-after-response strict-mode { on | off }
 
@@ -5753,6 +5757,7 @@
 
 
 http-check set-var(<var-name>) <expr>
+http-check set-var-fmt(<var-name>) <fmt>
   This operation sets the content of a variable. The variable is declared inline.
   May be used in sections:   defaults | frontend | listen | backend
                                yes    |    no    |   yes  |   yes
@@ -5769,8 +5774,12 @@
 
     <expr>      Is a sample-fetch expression potentially followed by converters.
 
+    <fmt>       This is the value expressed using log-format rules (see Custom
+                Log Format in section 8.2.4).
+
   Examples :
         http-check set-var(check.port) int(1234)
+        http-check set-var-fmt(check.port) "name=%H"
 
 
 http-check unset-var(<var-name>)
@@ -6746,6 +6755,7 @@
   See also "http-request set-path" and "http-request set-query".
 
 http-request set-var(<var-name>) <expr> [ { if | unless } <condition> ]
+http-request set-var-fmt(<var-name>) <fmt> [ { if | unless } <condition> ]
 
   This is used to set the contents of a variable. The variable is declared
   inline.
@@ -6768,8 +6778,13 @@
     <expr>      Is a standard HAProxy expression formed by a sample-fetch
                 followed by some converters.
 
+    <fmt>       This is the value expressed using log-format rules (see Custom
+                Log Format in section 8.2.4).
+
   Example:
     http-request set-var(req.my_var) req.fhdr(user-agent),lower
+    http-request set-var-fmt(txn.from) %[src]:%[src_port]
+
 
 http-request send-spoe-group <engine-name> <group-name>
                              [ { if | unless } <condition> ]
@@ -7316,6 +7331,7 @@
   See RFC 2474, 2597, 3260 and 4594 for more information.
 
 http-response set-var(<var-name>) <expr> [ { if | unless } <condition> ]
+http-response set-var-fmt(<var-name>) <fmt> [ { if | unless } <condition> ]
 
   This is used to set the contents of a variable. The variable is declared
   inline.
@@ -7338,8 +7354,12 @@
     <expr>      Is a standard HAProxy expression formed by a sample-fetch
                 followed by some converters.
 
-  Example:
-    http-response set-var(sess.last_redir) res.hdr(location)
+    <fmt>       This is the value expressed using log-format rules (see Custom
+                Log Format in section 8.2.4).
+
+  Examples:
+       http-response set-var(sess.last_redir) res.hdr(location)
+       http-response set-var-fmt(sess.last_be_addr) %[bi]:%[bp]
 
 http-response silent-drop [ { if | unless } <condition> ]
 
@@ -11883,6 +11903,7 @@
 
 
 tcp-check set-var(<var-name>) <expr>
+tcp-check set-var-fmt(<var-name>) <fmt>
   This operation sets the content of a variable. The variable is declared inline.
   May be used in sections:   defaults | frontend | listen | backend
                                yes    |    no    |   yes  |   yes
@@ -11899,8 +11920,12 @@
 
     <expr>      Is a sample-fetch expression potentially followed by converters.
 
+    <fmt>       This is the value expressed using log-format rules (see Custom
+                Log Format in section 8.2.4).
+
   Examples :
     tcp-check set-var(check.port) int(1234)
+    tcp-check set-var-fmt(check.name) "%H"
 
 
 tcp-check unset-var(<var-name>)
@@ -12266,6 +12291,7 @@
     - set-nice <nice>
     - set-tos <tos>
     - set-var(<var-name>) <expr>
+    - set-var-fmt(<var-name>) <fmt>
     - switch-mode http [ proto <name> ]
     - unset-var(<var-name>)
     - silent-drop
@@ -12327,9 +12353,11 @@
   The "set-tos" is used to set the TOS or DSCP field value of packets sent to
   the client. More information on how to use it at "http-request set-tos".
 
-  The "set-var" is used to set the content of a variable. The variable is
-  declared inline. For "tcp-request session" rules, only session-level
-  variables can be used, without any layer7 contents.
+  The "set-var" and "set-var-fmt" are used to set the contents of a variable.
+  The variable is declared inline. For "tcp-request session" rules, only
+  session-level variables can be used, without any layer7 contents. The
+  "set-var" action takes a regular expression while "set-var-fmt" takes a
+  format string.
 
     <var-name> The name of the variable starts with an indication about
                its scope. The scopes allowed are:
@@ -12348,6 +12376,9 @@
     <expr>     Is a standard HAProxy expression formed by a sample-fetch
                followed by some converters.
 
+    <fmt>       This is the value expressed using log-format rules (see Custom
+                Log Format in section 8.2.4).
+
   The "switch-mode" is used to perform a connection upgrade. Only HTTP
   upgrades are supported for now. The protocol may optionally be
   specified. This action is only available for a proxy with the frontend
@@ -12405,6 +12436,7 @@
   Example:
 
         tcp-request content set-var(sess.my_var) src
+        tcp-request content set-var-fmt(sess.from) %[src]:%[src_port]
         tcp-request content unset-var(sess.my_var2)
 
   Example:
@@ -12589,6 +12621,9 @@
     - set-var(<var-name>) <expr>
         Sets a variable from an expression.
 
+    - set-var-fmt(<var-name>) <fmt>
+        Sets a variable from a log format string.
+
     - unset-var(<var-name>)
         Unsets a variable.
 
@@ -12681,6 +12716,9 @@
     <expr>     Is a standard HAProxy expression formed by a sample-fetch
                followed by some converters.
 
+    <fmt>       This is the value expressed using log-format rules (see Custom
+                Log Format in section 8.2.4).
+
   The "unset-var" is used to unset a variable. See above for details about
   <var-name>.
 
@@ -12751,6 +12789,7 @@
     - set-src-port <expr>
     - set-tos <tos>
     - set-var(<var-name>) <expr>
+    - set-var-fmt(<var-name>) <fmt>
     - unset-var(<var-name>)
     - silent-drop
 
@@ -16153,13 +16192,16 @@
   other variables, such as colon-delimited values. If commas or closing
   parenthesis are needed as delimiters, they must be protected by quotes or
   backslashes, themselves protected so that they are not stripped by the first
-  level parser. See examples below.
+  level parser. This is often used to build composite variables from other
+  ones, but sometimes using a format string with multiple fields may be more
+  convenient. See examples below.
 
   Example:
     tcp-request session set-var(sess.src) src
     tcp-request session set-var(sess.dn)  ssl_c_s_dn
     tcp-request session set-var(txn.sig) str(),concat(<ip=,sess.ip,>),concat(<dn=,sess.dn,>)
     tcp-request session set-var(txn.ipport) "str(),concat('addr=(',sess.ip),concat(',',sess.port,')')"
+    tcp-request session set-var-fmt(txn.ipport) "addr=(%[sess.ip],%[sess.port])"  ## does the same
     http-request set-header x-hap-sig %[var(txn.sig)]
 
 cpl
diff --git a/include/haproxy/action-t.h b/include/haproxy/action-t.h
index cceed80..bb243c1 100644
--- a/include/haproxy/action-t.h
+++ b/include/haproxy/action-t.h
@@ -162,6 +162,7 @@
 		} timeout;
 		struct hlua_rule *hlua_rule;
 		struct {
+			struct list fmt;            /* log-format compatible expression */
 			struct sample_expr *expr;
 			const char *name;
 			enum vars_scope scope;
diff --git a/reg-tests/sample_fetches/vars.vtc b/reg-tests/sample_fetches/vars.vtc
index 01e25b9..95ab68d 100644
--- a/reg-tests/sample_fetches/vars.vtc
+++ b/reg-tests/sample_fetches/vars.vtc
@@ -1,5 +1,5 @@
 varnishtest "Test a few set-var() in global, tcp and http rule sets, at different scopes"
-#REQUIRE_VERSION=2.4
+feature cmd "$HAPROXY_PROGRAM -cc 'version_atleast(2.5-dev5)'"
 
 feature ignore_unknown_macro
 
@@ -7,7 +7,9 @@
     global
         set-var proc.int12 int(12)
         set-var proc.int5  str(60),div(proc.int12)
-        set-var proc.str   str("this is")
+        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 proc.uuid  uuid()
 
@@ -19,11 +21,14 @@
 
     frontend fe1
         bind "fd@${fe1}"
+        tcp-request session set-var-fmt(sess.str3) "%[var(proc.str1)] %[var(proc.str2)]"
         tcp-request session set-var(sess.int5) var(proc.int5)
         tcp-request session set-var(proc.int5) var(proc.int5),add(sess.int5) ## proc. becomes 10
+        tcp-request content set-var-fmt(req.str4) "%[var(sess.str3),regsub(is a,is also a)]"
+        http-request set-var-fmt(txn.str5)  "%[var(req.str4)]"
         http-request set-var(req.int5)  var(sess.int5)
         http-request set-var(sess.int5) var(sess.int5),add(req.int5) ## sess. becomes 10 first time, then 15...
-	http-request return status 200 hdr x-var "proc=%[var(proc.int5)] sess=%[var(sess.int5)] req=%[var(req.int5)] str=%[var(proc.str)] uuid=%[var(proc.uuid)]"
+	http-request return status 200 hdr x-var "proc=%[var(proc.int5)] sess=%[var(sess.int5)] req=%[var(req.int5)] str=%[var(proc.str)] str5=%[var(txn.str5)] uuid=%[var(proc.uuid)]"
 } -start
 
 haproxy h1 -cli {
@@ -35,12 +40,12 @@
     txreq -req GET -url /req1_1
     rxresp
     expect resp.status == 200
-    expect resp.http.x-var ~ "proc=10 sess=10 req=5 str=this is a string uuid=[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*"
+    expect resp.http.x-var ~ "proc=10 sess=10 req=5 str=this is a string str5=this is also a string uuid=[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*"
 
     txreq -req GET -url /req1_2
     rxresp
     expect resp.status == 200
-    expect resp.http.x-var ~ "proc=10 sess=20 req=10 str=this is a string uuid=[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*"
+    expect resp.http.x-var ~ "proc=10 sess=20 req=10 str=this is a string str5=this is also a string uuid=[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*"
 } -run
 
 haproxy h1 -cli {
@@ -52,12 +57,12 @@
     txreq -req GET -url /req2_1
     rxresp
     expect resp.status == 200
-    expect resp.http.x-var ~ "proc=20 sess=20 req=10 str=this is a string uuid=[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*"
+    expect resp.http.x-var ~ "proc=20 sess=20 req=10 str=this is a string str5=this is also a string uuid=[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*"
 
     txreq -req GET -url /req2_2
     rxresp
     expect resp.status == 200
-    expect resp.http.x-var ~ "proc=20 sess=40 req=20 str=this is a string uuid=[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*"
+    expect resp.http.x-var ~ "proc=20 sess=40 req=20 str=this is a string str5=this is also a string uuid=[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*"
 } -run
 
 haproxy h1 -cli {
@@ -74,5 +79,5 @@
     txreq -req GET -url /req3_1
     rxresp
     expect resp.status == 200
-    expect resp.http.x-var ~ "proc=40 sess=40 req=20 str=updated uuid=[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*"
+    expect resp.http.x-var ~ "proc=40 sess=40 req=20 str=updated str5=this is also a string uuid=[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*"
 } -run
diff --git a/src/vars.c b/src/vars.c
index 156eb94..bf53d87 100644
--- a/src/vars.c
+++ b/src/vars.c
@@ -649,6 +649,7 @@
 static enum act_return action_store(struct act_rule *rule, struct proxy *px,
                                     struct session *sess, struct stream *s, int flags)
 {
+	struct buffer *fmtstr = NULL;
 	struct sample smp;
 	int dir;
 
@@ -670,12 +671,39 @@
 
 	/* Process the expression. */
 	memset(&smp, 0, sizeof(smp));
-	if (!sample_process(px, sess, s, dir|SMP_OPT_FINAL,
-	                    rule->arg.vars.expr, &smp))
-		return ACT_RET_CONT;
+
+	if (!LIST_ISEMPTY(&rule->arg.vars.fmt)) {
+		/* a format-string is used */
+
+		fmtstr = alloc_trash_chunk();
+		if (!fmtstr) {
+			send_log(px, LOG_ERR, "Vars: memory allocation failure while processing store rule.");
+			if (!(global.mode & MODE_QUIET) || (global.mode & MODE_VERBOSE))
+				ha_alert("Vars: memory allocation failure while processing store rule.\n");
+			return ACT_RET_CONT;
+		}
+
+		/* execute the log-format expression */
+		fmtstr->data = sess_build_logline(sess, s, fmtstr->area, fmtstr->size, &rule->arg.vars.fmt);
+
+		/* convert it to a sample of type string as it's what the vars
+		 * API consumes, and store it.
+		 */
+		smp_set_owner(&smp, px, sess, s, 0);
+		smp.data.type = SMP_T_STR;
+		smp.data.u.str = *fmtstr;
+		sample_store_stream(rule->arg.vars.name, rule->arg.vars.scope, &smp);
+	}
+	else {
+		/* an expression is used */
+		if (!sample_process(px, sess, s, dir|SMP_OPT_FINAL,
+	                            rule->arg.vars.expr, &smp))
+			return ACT_RET_CONT;
+	}
 
 	/* Store the sample, and ignore errors. */
 	sample_store_stream(rule->arg.vars.name, rule->arg.vars.scope, &smp);
+	free_trash_chunk(fmtstr);
 	return ACT_RET_CONT;
 }
 
@@ -695,6 +723,14 @@
 
 static void release_store_rule(struct act_rule *rule)
 {
+	struct logformat_node *lf, *lfb;
+	list_for_each_entry_safe(lf, lfb, &rule->arg.http.fmt, list) {
+		LIST_DELETE(&lf->list);
+		release_sample_expr(lf->expr);
+		free(lf->arg);
+		free(lf);
+	}
+
 	release_sample_expr(rule->arg.vars.expr);
 }
 
@@ -720,6 +756,7 @@
 /* This function is a common parser for using variables. It understands
  * the format:
  *
+ *   set-var-fmt(<variable-name>) <format-string>
  *   set-var(<variable-name>) <expression>
  *   unset-var(<variable-name>)
  *
@@ -734,9 +771,13 @@
 	const char *var_name = args[*arg-1];
 	int var_len;
 	const char *kw_name;
-	int flags, set_var = 0;
+	int flags, set_var = 0; /* 0=unset-var, 1=set-var, 2=set-var-fmt */
 
-	if (strncmp(var_name, "set-var", 7) == 0) {
+	if (strncmp(var_name, "set-var-fmt", 11) == 0) {
+		var_name += 11;
+		set_var   = 2;
+	}
+	else if (strncmp(var_name, "set-var", 7) == 0) {
 		var_name += 7;
 		set_var   = 1;
 	}
@@ -746,7 +787,7 @@
 	}
 
 	if (*var_name != '(') {
-		memprintf(err, "invalid or incomplete action '%s'. Expects 'set-var(<var-name>)' or 'unset-var(<var-name>)'",
+		memprintf(err, "invalid or incomplete action '%s'. Expects 'set-var(<var-name>)', 'set-var-fmt(<var-name>)' or 'unset-var(<var-name>)'",
 			  args[*arg-1]);
 		return ACT_RET_PRS_ERR;
 	}
@@ -754,11 +795,12 @@
 	var_len = strlen(var_name);
 	var_len--; /* remove the ')' */
 	if (var_name[var_len] != ')') {
-		memprintf(err, "incomplete expression after action '%s'. Expects 'set-var(<var-name>)' or 'unset-var(<var-name>)'",
+		memprintf(err, "incomplete argument after action '%s'. Expects 'set-var(<var-name>)', 'set-var-fmt(<var-name>)' or 'unset-var(<var-name>)'",
 			  args[*arg-1]);
 		return ACT_RET_PRS_ERR;
 	}
 
+	LIST_INIT(&rule->arg.vars.fmt);
 	rule->arg.vars.name = register_name(var_name, var_len, &rule->arg.vars.scope, 1, err);
 	if (!rule->arg.vars.name)
 		return ACT_RET_PRS_ERR;
@@ -814,17 +856,30 @@
 		return ACT_RET_PRS_ERR;
 	}
 
-	rule->arg.vars.expr = sample_parse_expr((char **)args, arg, px->conf.args.file,
-	                                        px->conf.args.line, err, &px->conf.args, NULL);
-	if (!rule->arg.vars.expr)
-		return ACT_RET_PRS_ERR;
+	if (set_var == 2) { /* set-var-fmt */
+		if (!parse_logformat_string(args[*arg], px, &rule->arg.vars.fmt, 0, flags, err))
+			return ACT_RET_PRS_ERR;
 
-	if (!(rule->arg.vars.expr->fetch->val & flags)) {
-		memprintf(err,
-			  "fetch method '%s' extracts information from '%s', none of which is available here",
-			  kw_name, sample_src_names(rule->arg.vars.expr->fetch->use));
-		free(rule->arg.vars.expr);
-		return ACT_RET_PRS_ERR;
+		(*arg)++;
+
+		/* for late error reporting */
+		free(px->conf.lfs_file);
+		px->conf.lfs_file = strdup(px->conf.args.file);
+		px->conf.lfs_line = px->conf.args.line;
+	} else {
+		/* set-var */
+		rule->arg.vars.expr = sample_parse_expr((char **)args, arg, px->conf.args.file,
+	                                                px->conf.args.line, err, &px->conf.args, NULL);
+		if (!rule->arg.vars.expr)
+			return ACT_RET_PRS_ERR;
+
+		if (!(rule->arg.vars.expr->fetch->val & flags)) {
+			memprintf(err,
+			          "fetch method '%s' extracts information from '%s', none of which is available here",
+			          kw_name, sample_src_names(rule->arg.vars.expr->fetch->use));
+			free(rule->arg.vars.expr);
+			return ACT_RET_PRS_ERR;
+		}
 	}
 
 	rule->action     = ACT_CUSTOM;
@@ -1085,6 +1140,7 @@
 INITCALL1(STG_REGISTER, sample_register_convs, &sample_conv_kws);
 
 static struct action_kw_list tcp_req_sess_kws = { { }, {
+	{ "set-var-fmt", parse_store, KWF_MATCH_PREFIX },
 	{ "set-var",   parse_store, KWF_MATCH_PREFIX },
 	{ "unset-var", parse_store, KWF_MATCH_PREFIX },
 	{ /* END */ }
@@ -1093,6 +1149,7 @@
 INITCALL1(STG_REGISTER, tcp_req_sess_keywords_register, &tcp_req_sess_kws);
 
 static struct action_kw_list tcp_req_cont_kws = { { }, {
+	{ "set-var-fmt", parse_store, KWF_MATCH_PREFIX },
 	{ "set-var",   parse_store, KWF_MATCH_PREFIX },
 	{ "unset-var", parse_store, KWF_MATCH_PREFIX },
 	{ /* END */ }
@@ -1101,6 +1158,7 @@
 INITCALL1(STG_REGISTER, tcp_req_cont_keywords_register, &tcp_req_cont_kws);
 
 static struct action_kw_list tcp_res_kws = { { }, {
+	{ "set-var-fmt", parse_store, KWF_MATCH_PREFIX },
 	{ "set-var",   parse_store, KWF_MATCH_PREFIX },
 	{ "unset-var", parse_store, KWF_MATCH_PREFIX },
 	{ /* END */ }
@@ -1109,6 +1167,7 @@
 INITCALL1(STG_REGISTER, tcp_res_cont_keywords_register, &tcp_res_kws);
 
 static struct action_kw_list tcp_check_kws = {ILH, {
+	{ "set-var-fmt", parse_store, KWF_MATCH_PREFIX },
 	{ "set-var",   parse_store, KWF_MATCH_PREFIX },
 	{ "unset-var", parse_store, KWF_MATCH_PREFIX },
 	{ /* END */ }
@@ -1117,6 +1176,7 @@
 INITCALL1(STG_REGISTER, tcp_check_keywords_register, &tcp_check_kws);
 
 static struct action_kw_list http_req_kws = { { }, {
+	{ "set-var-fmt", parse_store, KWF_MATCH_PREFIX },
 	{ "set-var",   parse_store, KWF_MATCH_PREFIX },
 	{ "unset-var", parse_store, KWF_MATCH_PREFIX },
 	{ /* END */ }
@@ -1125,6 +1185,7 @@
 INITCALL1(STG_REGISTER, http_req_keywords_register, &http_req_kws);
 
 static struct action_kw_list http_res_kws = { { }, {
+	{ "set-var-fmt", parse_store, KWF_MATCH_PREFIX },
 	{ "set-var",   parse_store, KWF_MATCH_PREFIX },
 	{ "unset-var", parse_store, KWF_MATCH_PREFIX },
 	{ /* END */ }
@@ -1133,6 +1194,7 @@
 INITCALL1(STG_REGISTER, http_res_keywords_register, &http_res_kws);
 
 static struct action_kw_list http_after_res_kws = { { }, {
+	{ "set-var-fmt", parse_store, KWF_MATCH_PREFIX },
 	{ "set-var",   parse_store, KWF_MATCH_PREFIX },
 	{ "unset-var", parse_store, KWF_MATCH_PREFIX },
 	{ /* END */ }