From b094d7b4078ca4f0c357f455198336f27977192f Mon Sep 17 00:00:00 2001
From: Ian Barwick <ian@2ndquadrant.com>
Date: Thu, 1 Jul 2021 13:04:23 +0900
Subject: [PATCH] standby clone: set "slot_name" in node record if required

If executing "repmgr standby clone --replication-conf-only" on a node
which was set up without replication slots, but the repmgr configuration
was since changed to "use_replication_slots=1", repmgr will attempt to
create the replication slot. This will however fail if "slot_name"
is not set in the node's record, so have repmgr set the slot_name in
this case.

It might be preferable to preemptively create the slot name for each
node when configuring the cluster, however this would be a behavioural
change which would be better off in a major release (for example, it's
conceivable a user runs sanity checks on the node records and expects
to find the slot names empty if replication slots are not in use).
---
 repmgr-action-standby.c | 58 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/repmgr-action-standby.c b/repmgr-action-standby.c
index 5ba51484..846806a7 100644
--- a/repmgr-action-standby.c
+++ b/repmgr-action-standby.c
@@ -1300,6 +1300,64 @@ _do_create_replication_conf(void)
 		PQExpBufferData msg;
 		t_replication_slot slot_info = T_REPLICATION_SLOT_INITIALIZER;
 
+		/*
+		 * Check the node record has slot_name set; if not we'll need to
+		 * update it.
+		 */
+		if (local_node_record.slot_name[0] == '\0')
+		{
+			PGconn	   *primary_conn = NULL;
+
+			create_slot_name(local_node_record.slot_name, local_node_record.node_id);
+
+			/* Check we can connect to the primary so we can update the record */
+
+			if (get_recovery_type(upstream_conn) == RECTYPE_PRIMARY)
+			{
+				primary_conn = upstream_conn;
+			}
+			else
+			{
+				primary_conn = establish_primary_db_connection(upstream_conn, false);
+
+				if (primary_conn == NULL)
+				{
+					log_error(_("unable to connect to primary to update slot name for node \"%s\" (ID: %i)"),
+							  local_node_record.node_name,
+							  local_node_record.node_id);
+					PQfinish(upstream_conn);
+					termPQExpBuffer(&msg);
+					exit(ERR_BAD_CONFIG);
+				}
+			}
+
+			if (runtime_options.dry_run == true)
+			{
+				log_info(_("would set \"slot_name\" for node \"%s\" (ID: %i) to \"%s\""),
+						  local_node_record.node_name,
+						  local_node_record.node_id,
+						  local_node_record.slot_name);
+			}
+			else
+			{
+				bool success = update_node_record_slot_name(primary_conn,
+															local_node_record.node_id,
+															local_node_record.slot_name);
+
+				if (primary_conn != upstream_conn)
+					PQfinish(primary_conn);
+
+				if (success == false)
+				{
+					log_error(_("unable to update slot name for node \"%s\" (ID: %i)"),
+							  local_node_record.node_name,
+							  local_node_record.node_id);
+					PQfinish(upstream_conn);
+					exit(ERR_BAD_CONFIG);
+				}
+			}
+		}
+
 		record_status = get_slot_record(upstream_conn, local_node_record.slot_name, &slot_info);
 
 		/* check if replication slot exists*/