From 63d79e2b4fac043e29ea4d54589fbb8788a18ffd Mon Sep 17 00:00:00 2001
From: Grigory Smolkin <g.smolkin@postgrespro.ru>
Date: Wed, 10 Feb 2021 15:10:15 +0300
Subject: [PATCH] [Issue #323] stable remote agent API

---
 src/pg_probackup.h | 3 +++
 src/utils/remote.c | 5 +++--
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/pg_probackup.h b/src/pg_probackup.h
index a766e705..c15e6efd 100644
--- a/src/pg_probackup.h
+++ b/src/pg_probackup.h
@@ -307,7 +307,10 @@ typedef enum ShowFormat
 #define FILE_NOT_FOUND		(-2) /* file disappeared during backup */
 #define BLOCKNUM_INVALID	(-1)
 #define PROGRAM_VERSION	"2.4.9"
+
+/* update when remote agent API or behaviour changes */
 #define AGENT_PROTOCOL_VERSION 20409
+#define AGENT_PROTOCOL_VERSION_STR "2.4.9"
 
 /* update only when changing storage format */
 #define STORAGE_FORMAT_VERSION "2.4.4"
diff --git a/src/utils/remote.c b/src/utils/remote.c
index 88b1ce7a..2bfd24d1 100644
--- a/src/utils/remote.c
+++ b/src/utils/remote.c
@@ -247,8 +247,9 @@ bool launch_agent(void)
 				(agent_version / 100) % 100,
 				agent_version % 100);
 
-		elog(ERROR, "Remote agent version %s does not match local program version %s",
-			agent_version_str, PROGRAM_VERSION);
+		elog(ERROR, "Remote agent protocol version %s does not match local program protocol version %s, "
+					"consider to upgrade pg_probackup binary",
+			agent_version_str, AGENT_PROTOCOL_VERSION_STR);
 	}
 
 	return true;