From 2594a46a4fd0a8c14f00653a594bee2132591aa2 Mon Sep 17 00:00:00 2001
From: Ian Barwick <ian@2ndquadrant.com>
Date: Thu, 13 Jul 2017 14:10:08 +0900
Subject: [PATCH] Limit repmgr installation on a BDR cluster to two nodes

---
 repmgr-action-bdr.c | 25 +++++++++++++++++++++----
 repmgr-client.c     |  6 ++++--
 2 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/repmgr-action-bdr.c b/repmgr-action-bdr.c
index ac51240d..13853f63 100644
--- a/repmgr-action-bdr.c
+++ b/repmgr-action-bdr.c
@@ -22,6 +22,7 @@ void
 do_bdr_register(void)
 {
 	PGconn	   	   *conn = NULL;
+	BdrNodeInfoList bdr_nodes = T_BDR_NODE_INFO_LIST_INITIALIZER;
     ExtensionStatus extension_status;
 	t_node_info		node_info = T_NODE_INFO_INITIALIZER;
 	RecordStatus	record_status;
@@ -45,6 +46,25 @@ do_bdr_register(void)
 	{
 		log_error(_("database \"%s\" is not BDR-enabled"), dbname);
 		log_hint(_("when using repmgr with BDR, the repmgr schema must be stored in the BDR database"));
+		PQfinish(conn);
+		exit(ERR_BAD_CONFIG);
+	}
+
+	/* Check that there are at most 2 BDR nodes */
+	get_all_bdr_node_records(conn, &bdr_nodes);
+
+	if (bdr_nodes.node_count == 0)
+	{
+		log_error(_("database \"%s\" is BDR-enabled but no BDR nodes were found"), dbname);
+		PQfinish(conn);
+		exit(ERR_BAD_CONFIG);
+	}
+
+	if (bdr_nodes.node_count > 2)
+	{
+		log_error(_("repmgr can only support BDR clusters with 2 nodes"));
+		log_detail(_("this BDR cluster has %i nodes"), bdr_nodes.node_count);
+		PQfinish(conn);
 		exit(ERR_BAD_CONFIG);
 	}
 
@@ -54,12 +74,10 @@ do_bdr_register(void)
 	if (extension_status == REPMGR_UNKNOWN)
 	{
 		log_error(_("unable to determine status of \"repmgr\" extension in database \"%s\""),
-				  dbname
-);
+				  dbname);
 		PQfinish(conn);
 	}
 
-
 	if (extension_status == REPMGR_UNAVAILABLE)
 	{
 		log_error(_("\"repmgr\" extension is not available"));
@@ -73,7 +91,6 @@ do_bdr_register(void)
 			log_error(_("repmgr metadatabase contains records for non-BDR nodes"));
 			exit(ERR_BAD_CONFIG);
 		}
-
 	}
 	else
 	{
diff --git a/repmgr-client.c b/repmgr-client.c
index 255fcd82..234f6362 100644
--- a/repmgr-client.c
+++ b/repmgr-client.c
@@ -1242,12 +1242,14 @@ do_help(void)
 	}
 
 	printf(_("Usage:\n"));
-	printf(_("	%s [OPTIONS] primary  register\n"), progname());
-	printf(_("	%s [OPTIONS] primary  unregister\n"), progname());
+	printf(_("	%s [OPTIONS] primary register\n"), progname());
+	printf(_("	%s [OPTIONS] primary unregister\n"), progname());
 	printf(_("	%s [OPTIONS] standby clone\n"), progname());
 	printf(_("	%s [OPTIONS] standby register\n"), progname());
 	printf(_("	%s [OPTIONS] standby unregister\n"), progname());
 	printf(_("	%s [OPTIONS] standby promote\n"), progname());
+	printf(_("	%s [OPTIONS] bdr     register\n"), progname());
+	printf(_("	%s [OPTIONS] bdr     unregister\n"), progname());
 	printf(_("	%s [OPTIONS] cluster event\n"), progname());
 
 	puts("");