repmgr standby follow: main code

dbutils.c

@@ -1545,6 +1545,49 @@ update_node_record_set_master(PGconn *conn, int this_node_id)
 }
 
 
+/*
+ * Update node record following change of status
+ * (e.g. inactive primary converted to standby)
+ */
+bool
+update_node_record_status(PGconn *conn, int this_node_id, char *type, int upstream_node_id, bool active)
+{
+	PQExpBufferData	  query;
+	PGresult   *res;
+
+	initPQExpBuffer(&query);
+
+	appendPQExpBuffer(&query,
+					  "  UPDATE repmgr.nodes "
+					  "     SET type = '%s', "
+					  "         upstream_node_id = %i, "
+					  "         active = %s "
+					  "   WHERE node_id = %i ",
+					  type,
+					  upstream_node_id,
+					  active ? "TRUE" : "FALSE",
+					  this_node_id);
+
+	log_verbose(LOG_DEBUG, "update_node_record_status():\n  %s", query.data);
+
+	res = PQexec(conn, query.data);
+	termPQExpBuffer(&query);
+
+	if (PQresultStatus(res) != PGRES_COMMAND_OK)
+	{
+		log_error(_("unable to update node record:\n  %s"),
+				PQerrorMessage(conn));
+		PQclear(res);
+
+		return false;
+	}
+
+	PQclear(res);
+
+	return true;
+}
+
+
 
 bool
 delete_node_record(PGconn *conn, int node)
@@ -1906,7 +1949,7 @@ create_replication_slot(PGconn *conn, char *slot_name, int server_version_num, P
 						  slot_name);
 	}
 
-	log_debug(_("create_replication_slot(): Creating slot '%s' on upstream"), slot_name);
+	log_debug(_("create_replication_slot(): creating slot '%s' on upstream"), slot_name);
 	log_verbose(LOG_DEBUG, "create_replication_slot():\n%s", query.data);
 
 	res = PQexec(conn, query.data);
@@ -1915,7 +1958,7 @@ create_replication_slot(PGconn *conn, char *slot_name, int server_version_num, P
 	if (!res || PQresultStatus(res) != PGRES_TUPLES_OK)
 	{
 		appendPQExpBuffer(error_msg,
-						  _("unable to create slot '%s' on the master node: %s\n"),
+						  _("unable to create slot '%s' on the upstream node: %s\n"),
 						  slot_name,
 						  PQerrorMessage(conn));
 		PQclear(res);

dbutils.h

@@ -208,6 +208,7 @@ bool		update_node_record(PGconn *conn, char *repmgr_action, t_node_info *node_in
 bool		delete_node_record(PGconn *conn, int node);
 
 bool		update_node_record_set_master(PGconn *conn, int this_node_id);
+bool        update_node_record_status(PGconn *conn, int this_node_id, char *type, int upstream_node_id, bool active);
 
 /* event record functions */
 bool        create_event_record(PGconn *conn, t_configuration_options *options, int node_id, char *event, bool successful, char *details);

repmgr-action-standby.c

@@ -73,6 +73,8 @@ static void copy_configuration_files(void);
 static int run_basebackup(void);
 static int run_file_backup(void);
 
+static void drop_replication_slot_if_exists(PGconn *conn, int node_id, char *slot_name);
+
 static void tablespace_data_append(TablespaceDataList *list, const char *name, const char *oid, const char *location);
 
 static void get_barman_property(char *dst, char *name, char *local_repmgr_directory);
@@ -1225,7 +1227,20 @@ void
 do_standby_follow(void)
 {
 	PGconn	   *local_conn;
+	t_node_info local_node_record = T_NODE_INFO_INITIALIZER;
+	int			original_upstream_node_id = UNKNOWN_NODE_ID;
+
+	PGconn	   *master_conn = NULL;
+	int			master_id = UNKNOWN_NODE_ID;
+	t_node_info master_node_record = T_NODE_INFO_INITIALIZER;
+
 	char		data_dir[MAXPGPATH];
+	t_conninfo_param_list recovery_conninfo;
+	char	   *errmsg = NULL;
+	int			query_result;
+	char		restart_command[MAXLEN];
+	int			r;
+
 
 	log_verbose(LOG_DEBUG, "do_standby_follow()");
 
@@ -1237,9 +1252,6 @@ do_standby_follow(void)
 	if (runtime_options.host_param_provided == false)
 	{
 		bool	    success;
-		PGconn	   *master_conn = NULL;
-		char		master_conninfo[MAXLEN];
-		int			master_id = UNKNOWN_NODE_ID;
 		int	    	timer;
 
 		local_conn = establish_db_connection(config_file_options.conninfo, true);
@@ -1268,7 +1280,7 @@ do_standby_follow(void)
 		{
 			master_conn = get_master_connection(local_conn,
 											    &master_id,
-												(char *) &master_conninfo);
+												NULL);
 
 			if (PQstatus(master_conn) == CONNECTION_OK || runtime_options.wait == false)
 			{
@@ -1283,8 +1295,250 @@ do_standby_follow(void)
 			exit(ERR_BAD_CONFIG);
 		}
 
-		puts("OK");
+		check_master_standby_version_match(local_conn, master_conn);
+
+		PQfinish(local_conn);
 	}
+	/* local data directory and primary server info explictly provided -
+	 * attempt to connect to that
+	 *
+	 * XXX --wait option won't be effective here
+	 */
+	else
+	{
+		master_conn = establish_db_connection_by_params(
+			(const char**)source_conninfo.keywords,
+			(const char**)source_conninfo.values,
+			true);
+
+		master_id = get_master_node_id(master_conn);
+		strncpy(data_dir, runtime_options.data_dir, MAXPGPATH);
+	}
+
+	if (get_recovery_type(master_conn) != RECTYPE_MASTER)
+	{
+		log_error(_("the node to follow is not a master"));
+		// XXX log detail
+		PQfinish(master_conn);
+		exit(ERR_BAD_CONFIG);
+	}
+
+
+
+	/*
+	 * If 9.4 or later, and replication slots in use, we'll need to create a
+	 * slot on the new master
+	 */
+
+	if (config_file_options.use_replication_slots)
+	{
+ 		int	server_version_num = get_server_version(master_conn, NULL);
+
+		PQExpBufferData event_details;
+		initPQExpBuffer(&event_details);
+
+		if (create_replication_slot(master_conn, repmgr_slot_name, server_version_num, &event_details) == false)
+		{
+			log_error("%s", event_details.data);
+
+			create_event_record(master_conn,
+								&config_file_options,
+								config_file_options.node_id,
+								"standby_follow",
+								false,
+								event_details.data);
+
+			PQfinish(master_conn);
+			exit(ERR_DB_QUERY);
+		}
+
+		termPQExpBuffer(&event_details);
+	}
+
+	get_node_record(master_conn, master_id, &master_node_record);
+
+	/* Initialise connection parameters to write as `primary_conninfo` */
+	initialize_conninfo_params(&recovery_conninfo, false);
+
+	/* We ignore any application_name set in the master's conninfo */
+	parse_conninfo_string(master_node_record.conninfo, &recovery_conninfo, errmsg, true);
+
+
+	/* Set the default application name to this node's name */
+	param_set(&recovery_conninfo, "application_name", config_file_options.node_name);
+
+	/* Set the replication user from the master node record */
+	param_set(&recovery_conninfo, "user", master_node_record.repluser);
+
+	/*
+	 * Fetch our node record so we can write application_name, if set,
+	 * and to get the upstream node ID, which we'll need to know if
+	 * replication slots are in use and we want to delete the old slot.
+	 */
+	query_result = get_node_record(master_conn,
+								   config_file_options.node_id,
+								   &local_node_record);
+
+	if (query_result != 1)
+	{
+		/* this shouldn't happen, but if it does we'll plough on regardless */
+		log_warning(_("unable to retrieve record for node %i"),
+					config_file_options.node_id);
+	}
+	else
+	{
+		t_conninfo_param_list local_node_conninfo;
+		bool parse_success;
+
+		initialize_conninfo_params(&local_node_conninfo, false);
+
+		parse_success = parse_conninfo_string(local_node_record.conninfo, &local_node_conninfo, errmsg, false);
+
+		if (parse_success == false)
+		{
+			/* this shouldn't happen, but if it does we'll plough on regardless */
+			log_warning(_("unable to parse conninfo string \"%s\":\n  %s"),
+						local_node_record.conninfo, errmsg);
+		}
+		else
+		{
+			char *application_name = param_get(&local_node_conninfo, "application_name");
+
+			if (application_name != NULL && strlen(application_name))
+				param_set(&recovery_conninfo, "application_name", application_name);
+		}
+
+		/*
+		 * store the original upstream node id so we can delete the replication slot,
+		 * if exists
+		 */
+		if (local_node_record.upstream_node_id != UNKNOWN_NODE_ID)
+		{
+			original_upstream_node_id = local_node_record.upstream_node_id;
+		}
+		else
+		{
+			original_upstream_node_id = master_id;
+		}
+	}
+	{
+		char *list = param_list_to_string(&recovery_conninfo);
+		printf("recovery: %s\n", list);
+	}
+
+	log_info(_("changing standby's master to node %i"), master_id);
+
+	if (!create_recovery_file(data_dir, &recovery_conninfo))
+	{
+		PQfinish(master_conn);
+		exit(ERR_BAD_CONFIG);
+	}
+
+	/* restart the service */
+
+	// XXX here check if service is running!! if not, start
+	//     ensure that problem with pg_ctl output is caught here
+	if (*config_file_options.service_restart_command)
+	{
+		maxlen_snprintf(restart_command, "%s", config_file_options.service_restart_command);
+	}
+	else
+	{
+		maxlen_snprintf(restart_command,
+						"%s %s -w -D %s -m fast restart",
+				        make_pg_path("pg_ctl"),
+						config_file_options.pg_ctl_options,
+						data_dir);
+	}
+
+
+	log_notice(_("restarting server using '%s'"),
+			   restart_command);
+
+	r = system(restart_command);
+	if (r != 0)
+	{
+		log_error(_("unable to restart server"));
+		PQfinish(master_conn);
+		exit(ERR_NO_RESTART);
+	}
+
+
+	/*
+	 * If replication slots are in use, and an inactive one for this node
+	 * exists on the former upstream, drop it.
+	 *
+	 * XXX check if former upstream is current master?
+	 */
+
+	if (config_file_options.use_replication_slots && runtime_options.host_param_provided == false && original_upstream_node_id != UNKNOWN_NODE_ID)
+	{
+		t_node_info upstream_node_record  = T_NODE_INFO_INITIALIZER;
+		int			upstream_query_result;
+
+		log_verbose(LOG_INFO, "attempting to remove replication slot from old upstream node %i",
+					original_upstream_node_id);
+
+		/* XXX should we poll for server restart? */
+		local_conn = establish_db_connection(config_file_options.conninfo, true);
+
+		upstream_query_result = get_node_record(local_conn,
+												original_upstream_node_id,
+												&upstream_node_record);
+
+		PQfinish(local_conn);
+
+
+		if (upstream_query_result != 1)
+		{
+			log_warning(_("unable to retrieve node record for old upstream node %i"),
+						original_upstream_node_id);
+		}
+		else
+		{
+			PGconn *old_upstream_conn = establish_db_connection_quiet(upstream_node_record.conninfo);
+
+			if (PQstatus(old_upstream_conn) != CONNECTION_OK)
+			{
+				log_info(_("unable to connect to old upstream node %i to remove replication slot"),
+						 original_upstream_node_id);
+				log_hint(_("if reusing this node, you should manually remove any inactive replication slots"));
+			}
+			else
+			{
+				drop_replication_slot_if_exists(old_upstream_conn,
+												original_upstream_node_id,
+												local_node_record.slot_name);
+			}
+		}
+	}
+
+	/*
+	 * It's possible this node was an inactive primary - update the
+	 * relevant fields to ensure it's marked as an active standby
+	 */
+	if (update_node_record_status(master_conn,
+								  config_file_options.node_id,
+								  "standby",
+								  master_id,
+								  true) == false)
+	{
+		log_error(_("unable to update upstream node"));
+		PQfinish(master_conn);
+
+		exit(ERR_BAD_CONFIG);
+	}
+
+	log_notice(_("STANDBY FOLLOW successful"));
+
+	create_event_record(master_conn,
+						&config_file_options,
+						config_file_options.node_id,
+						"standby_follow",
+						true,
+						NULL);
+
+	PQfinish(master_conn);
 
 	return;
 }
@@ -2748,3 +3002,33 @@ check_recovery_type(PGconn *conn)
 		}
 	}
 }
+
+
+static void
+drop_replication_slot_if_exists(PGconn *conn, int node_id, char *slot_name)
+{
+	t_replication_slot  slot_info;
+	int					query_res;
+
+	query_res = get_slot_record(conn,slot_name, &slot_info);
+
+	if (query_res)
+	{
+		if (slot_info.active == false)
+		{
+			if (drop_replication_slot(conn, slot_name) == true)
+			{
+				log_notice(_("replication slot \"%s\" deleted on node %i"), slot_name, node_id);
+			}
+			else
+			{
+				log_error(_("unable to delete replication slot \"%s\" on node %i"), slot_name, node_id);
+			}
+		}
+		/* if active replication slot exists, call Houston as we have a problem */
+		else
+		{
+			log_warning(_("replication slot \"%s\" is still active on node %i"), slot_name, node_id);
+		}
+	}
+}