node check: add --upstream option

We have a --downstream option to check for attached nodes, but it
would be useful to have a corresponding --upstream option too.

A following patch will adapt the behaviour of this option when executed
on the primary node.

HISTORY

@@ -5,6 +5,7 @@
         repmgr: ensure postgresql.auto.conf is created with correct permissions (Ian)
         repmgr: minimize requirement to check upstream data directory location
           during "standby clone" (Ian)
+        repmgr: add --upstream option to "node check"
         repmgr: report error code on follow/rejoin failure due to non-available
           replication slot (Ian)
         repmgr: ensure "node rejoin" checks for available replication slots (Ian)

doc/repmgr-node-check.xml

@@ -82,6 +82,12 @@
       </simpara>
      </listitem>
 
+     <listitem>
+      <simpara>
+        <option>--upstream</option>: checks that the node is attached to its expected upstream
+      </simpara>
+     </listitem>
+
      <listitem>
       <simpara>
         <option>--slots</option>: checks there are no inactive physical replication slots

repmgr-action-node.c

@@ -44,6 +44,7 @@ static void _do_node_restore_config(void);
 static void do_node_check_replication_connection(void);
 static CheckStatus do_node_check_archive_ready(PGconn *conn, OutputMode mode, CheckStatusList *list_output);
 static CheckStatus do_node_check_downstream(PGconn *conn, OutputMode mode, CheckStatusList *list_output);
+static CheckStatus do_node_check_upstream(PGconn *conn, OutputMode mode, t_node_info *node_info, CheckStatusList *list_output);
 static CheckStatus do_node_check_replication_lag(PGconn *conn, OutputMode mode, t_node_info *node_info, CheckStatusList *list_output);
 static CheckStatus do_node_check_role(PGconn *conn, OutputMode mode, t_node_info *node_info, CheckStatusList *list_output);
 static CheckStatus do_node_check_slots(PGconn *conn, OutputMode mode, t_node_info *node_info, CheckStatusList *list_output);
@@ -791,6 +792,15 @@ do_node_check(void)
 		exit(return_code);
 	}
 
+	if (runtime_options.upstream == true)
+	{
+		return_code = do_node_check_upstream(conn,
+											 runtime_options.output_mode,
+											 &node_info,
+											 NULL);
+		PQfinish(conn);
+		exit(return_code);
+	}
 
 	if (runtime_options.replication_lag == true)
 	{
@@ -878,6 +888,9 @@ do_node_check(void)
 	if (do_node_check_downstream(conn, runtime_options.output_mode, &status_list) != CHECK_STATUS_OK)
 		issue_detected = true;
 
+	if (do_node_check_upstream(conn, runtime_options.output_mode, &node_info, &status_list) != CHECK_STATUS_OK)
+		issue_detected = true;
+
 	if (do_node_check_slots(conn, runtime_options.output_mode, &node_info, &status_list) != CHECK_STATUS_OK)
 		issue_detected = true;
 
@@ -1336,6 +1349,87 @@ do_node_check_downstream(PGconn *conn, OutputMode mode, CheckStatusList *list_ou
 }
 
 
+static CheckStatus
+do_node_check_upstream(PGconn *conn, OutputMode mode, t_node_info *node_info, CheckStatusList *list_output)
+{
+	PGconn	   *upstream_conn = NULL;
+	t_node_info upstream_node_info = T_NODE_INFO_INITIALIZER;
+	PQExpBufferData details;
+
+	CheckStatus status = CHECK_STATUS_OK;
+
+
+	if (mode == OM_CSV && list_output == NULL)
+	{
+		log_error(_("--csv output not provided with --upstream option"));
+		PQfinish(conn);
+		exit(ERR_BAD_CONFIG);
+	}
+
+	if (get_node_record(conn, node_info->upstream_node_id, &upstream_node_info) != RECORD_FOUND)
+	{
+		log_error(_("no record found for upstream node %i"), node_info->upstream_node_id);
+		PQfinish(conn);
+		exit(ERR_BAD_CONFIG);
+	}
+
+	initPQExpBuffer(&details);
+
+	upstream_conn = establish_db_connection(upstream_node_info.conninfo, true);
+
+	/* check our node is connected */
+	if (is_downstream_node_attached(upstream_conn, config_file_options.node_name) != NODE_ATTACHED)
+	{
+		appendPQExpBuffer(&details,
+						  _("node \"%s\" (ID: %i) is not attached to expected upstream node \"%s\" (ID: %i)"),
+						  node_info->node_name,
+						  node_info->node_id,
+						  upstream_node_info.node_name,
+						  upstream_node_info.node_id);
+		status = CHECK_STATUS_CRITICAL;
+	}
+	else
+	{
+		appendPQExpBuffer(&details,
+						  _("node \"%s\" (ID: %i) is attached to expected upstream node \"%s\" (ID: %i)"),
+						  node_info->node_name,
+						  node_info->node_id,
+						  upstream_node_info.node_name,
+						  upstream_node_info.node_id);
+	}
+
+	switch (mode)
+	{
+		case OM_NAGIOS:
+			{
+				printf("REPMGR_UPSTREAM_SERVER %s: %s | ",
+					   output_check_status(status),
+					   details.data);
+			}
+		case OM_TEXT:
+			if (list_output != NULL)
+			{
+				check_status_list_set(list_output,
+									  "Upstream connection",
+									  status,
+									  details.data);
+			}
+			else
+			{
+				printf("%s (%s)\n",
+					   output_check_status(status),
+					   details.data);
+			}
+		default:
+			break;
+	}
+
+	termPQExpBuffer(&details);
+
+	return status;
+}
+
+
 static CheckStatus
 do_node_check_replication_lag(PGconn *conn, OutputMode mode, t_node_info *node_info, CheckStatusList *list_output)
 {
@@ -3254,6 +3348,7 @@ do_node_help(void)
 	printf(_("  Following options check an individual status:\n"));
 	printf(_("    --archive-ready           number of WAL files ready for archiving\n"));
 	printf(_("    --downstream              whether all downstream nodes are connected\n"));
+	printf(_("    --uptream                 whether the node is connected to its upstream\n"));
 	printf(_("    --replication-lag         replication lag in seconds (standbys only)\n"));
 	printf(_("    --role                    check node has expected role\n"));
 	printf(_("    --slots                   check for inactive replication slots\n"));

repmgr-client-global.h

@@ -111,6 +111,7 @@ typedef struct
 	/* "node check" options */
 	bool		archive_ready;
 	bool		downstream;
+	bool		upstream;
 	bool		replication_lag;
 	bool		role;
 	bool		slots;
@@ -171,7 +172,7 @@ typedef struct
 		/* "node status" options */ \
 		false, \
 		/* "node check" options */ \
-		false, false, false, false, false, false, false, false,	false, false, \
+		false, false, false, false, false, false, false, false,	false, false, false, \
 		/* "node rejoin" options */ \
 		"", \
 		/* "node service" options */ \

repmgr-client.c

@@ -505,6 +505,10 @@ main(int argc, char **argv)
 				runtime_options.downstream = true;
 				break;
 
+			case OPT_UPSTREAM:
+				runtime_options.upstream = true;
+				break;
+
 			case OPT_REPLICATION_LAG:
 				runtime_options.replication_lag = true;
 				break;

repmgr-client.h

@@ -81,24 +81,25 @@
 #define OPT_SIBLINGS_FOLLOW				   1028
 #define OPT_ROLE						   1029
 #define OPT_DOWNSTREAM					   1030
-#define OPT_SLOTS						   1031
+#define OPT_UPSTREAM					   1031
-#define OPT_CONFIG_ARCHIVE_DIR			   1032
+#define OPT_SLOTS						   1032
-#define OPT_HAS_PASSFILE				   1033
+#define OPT_CONFIG_ARCHIVE_DIR			   1033
-#define OPT_WAIT_START					   1034
+#define OPT_HAS_PASSFILE				   1034
-#define OPT_REPL_CONN					   1035
+#define OPT_WAIT_START					   1035
-#define OPT_REMOTE_NODE_ID				   1036
+#define OPT_REPL_CONN					   1036
-#define OPT_REPLICATION_CONF_ONLY		   1037
+#define OPT_REMOTE_NODE_ID				   1037
-#define OPT_NO_WAIT						   1038
+#define OPT_REPLICATION_CONF_ONLY		   1038
-#define OPT_MISSING_SLOTS				   1039
+#define OPT_NO_WAIT						   1039
-#define OPT_REPMGRD_NO_PAUSE			   1040
+#define OPT_MISSING_SLOTS				   1040
-#define OPT_VERSION_NUMBER				   1041
+#define OPT_REPMGRD_NO_PAUSE			   1041
-#define OPT_DATA_DIRECTORY_CONFIG		   1042
+#define OPT_VERSION_NUMBER				   1042
-#define OPT_COMPACT						   1043
+#define OPT_DATA_DIRECTORY_CONFIG		   1043
-#define OPT_DISABLE_WAL_RECEIVER		   1044
+#define OPT_COMPACT						   1044
-#define OPT_ENABLE_WAL_RECEIVER			   1045
+#define OPT_DISABLE_WAL_RECEIVER		   1045
-#define OPT_DETAIL						   1046
+#define OPT_ENABLE_WAL_RECEIVER			   1046
-#define OPT_REPMGRD_FORCE_UNPAUSE		   1047
+#define OPT_DETAIL						   1047
-#define OPT_REPLICATION_CONFIG_OWNER	   1048
+#define OPT_REPMGRD_FORCE_UNPAUSE		   1048
+#define OPT_REPLICATION_CONFIG_OWNER	   1049
 
 /* deprecated since 4.0 */
 #define OPT_CHECK_UPSTREAM_CONFIG		    999
@@ -179,6 +180,7 @@ static struct option long_options[] =
 /* "node check" options */
 	{"archive-ready", no_argument, NULL, OPT_ARCHIVE_READY},
 	{"downstream", no_argument, NULL, OPT_DOWNSTREAM},
+	{"upstream", no_argument, NULL, OPT_UPSTREAM},
 	{"replication-lag", no_argument, NULL, OPT_REPLICATION_LAG},
 	{"role", no_argument, NULL, OPT_ROLE},
 	{"slots", no_argument, NULL, OPT_SLOTS},