Remove option "--wal-keep-segments"

This is a remnant of the early repmgr days when there were no alternative
mechanisms for ensuring sufficient WAL remains available while cloning a
standby.

The purpose of this setting was to override a check for an (arbitrary)
minimum setting for "wal_keep_segments". As there's no reliable way
of determining a sensible value for this, and improvements in
pg_basebackup mean WALs can be streamed (possibly using a replication
slot) while the backup is in progress, there's no point in keeping
this around.

We will however still emit a warning about setting "wal_keep_segments"
if the configuration doesn't appear to provide any other way of
ensuring WAL is available during/after the cloning process and
"wal_keep_segments" is not set.

repmgr-action-standby.c

@@ -87,10 +87,22 @@ static CheckStatus parse_node_check_archiver(const char *node_check_output, int
 static CheckStatus parse_node_check_replication_lag(const char *node_check_output, int *seconds, int *threshold);
 
 /*
- * do_standby_clone()
+ * STANDBY CLONE
  *
  * Event(s):
  *  - standby_clone
+ *
+ * Parameters:
+ *  --upstream-conninfo
+ *  --no-upstream-connection
+ *  -F/--force
+ *  --dry-run
+ *  -c/--fast-checkpoint
+ *  --copy-external-config-files
+ *  --recovery-min-apply-delay
+ *  --replication-user XXX only required if no upstream record
+ *  --use-recovery-conninfo-password
+ *  --without-barman
  */
 
 void

repmgr-client-global.h

@@ -22,7 +22,6 @@ typedef struct
 	bool		connection_param_provided;
 	bool		host_param_provided;
 	bool		limit_provided;
-	bool		wal_keep_segments_used;
 
 	/* general configuration options */
 	char		config_file[MAXPGPATH];
@@ -68,7 +67,6 @@ typedef struct
 	char		upstream_conninfo[MAXLEN];
 	int			upstream_node_id;
 	bool		use_recovery_conninfo_password;
-	char		wal_keep_segments[MAXLEN];
 	bool		without_barman;
 
 	/* "standby register" options */
@@ -111,7 +109,7 @@ typedef struct
 
 #define T_RUNTIME_OPTIONS_INITIALIZER { \
 		/* configuration metadata */ \
-		false, false, false, false,	false, 	\
+		false, false, false, false,	\
 		/* general configuration options */	\
 		"", false, false, "", false,	\
 		/* logging options */ \
@@ -126,7 +124,7 @@ typedef struct
 		UNKNOWN_NODE_ID, "", "", \
 		/* "standby clone" options */ \
 		false, CONFIG_FILE_SAMEPATH, false, false, false, "", "", "", \
-		NO_UPSTREAM_NODE, false, "", false,						 \
+		NO_UPSTREAM_NODE, false, false,						 \
 		/* "standby register" options */ \
 		false, 0, \
 		/* "standby switchover" options */ \

repmgr-client.c

@@ -334,15 +334,6 @@ main(int argc, char **argv)
 				}
 				break;
 
-			/* -w/--wal-keep-segments */
-			case 'w':
-				(void) repmgr_atoi(optarg, "-w/--wal-keep-segments", &cli_errors, false);
-				strncpy(runtime_options.wal_keep_segments,
-						optarg,
-						MAXLEN);
-				runtime_options.wal_keep_segments_used = true;
-				break;
-
 			/* --no-upstream-connection */
 			case OPT_NO_UPSTREAM_CONNECTION:
 				runtime_options.no_upstream_connection = true;
@@ -2160,23 +2151,13 @@ check_upstream_config(PGconn *conn, int server_version_num, bool exit_on_error)
 	else if (mode != barman)
 	{
 		bool check_wal_keep_segments = false;
-		char min_wal_keep_segments[MAXLEN] = "1";
-
-		/*
-		 * -w/--wal-keep-segments was supplied - check against that value
-		 */
-		if (runtime_options.wal_keep_segments_used == true)
-		{
-			check_wal_keep_segments = true;
-			strncpy(min_wal_keep_segments, runtime_options.wal_keep_segments, MAXLEN);
-		}
 
 		/*
 		 * A non-zero `wal_keep_segments` value will almost certainly be required
 		 * if pg_basebackup is being used with --xlog-method=fetch,
 		 * *and* no restore command has been specified
 		 */
-		else if (xlog_stream == false
+		if (xlog_stream == false
 			 && strcmp(config_file_options.restore_command, "") == 0)
 		{
 			check_wal_keep_segments = true;
@@ -2184,14 +2165,13 @@ check_upstream_config(PGconn *conn, int server_version_num, bool exit_on_error)
 
 		if (check_wal_keep_segments == true)
 		{
-			i = guc_set_typed(conn, "wal_keep_segments", ">=", min_wal_keep_segments, "integer");
+			i = guc_set_typed(conn, "wal_keep_segments", ">", "0", "integer");
 
 			if (i == 0 || i == -1)
 			{
 				if (i == 0)
 				{
-					log_error(_("parameter \"wal_keep_segments\" on the upstream server must be be set to %s or greater"),
+					log_error(_("parameter \"wal_keep_segments\" on the upstream server must be be set to a non-zero value"));
-							min_wal_keep_segments);
 					log_hint(_("Choose a value sufficiently high enough to retain enough WAL "
 							   "until the standby has been cloned and started.\n "
 							   "Alternatively set up WAL archiving using e.g. PgBarman and configure "

repmgr-client.h

@@ -118,7 +118,6 @@ static struct option long_options[] =
 /* "standby clone" options */
 	{"copy-external-config-files", optional_argument, NULL, OPT_COPY_EXTERNAL_CONFIG_FILES},
 	{"fast-checkpoint", no_argument, NULL, 'c'},
-	{"wal-keep-segments", required_argument, NULL, 'w'},
 	{"no-upstream-connection", no_argument, NULL, OPT_NO_UPSTREAM_CONNECTION},
 	{"recovery-min-apply-delay", required_argument, NULL, OPT_RECOVERY_MIN_APPLY_DELAY},
 	{"replication-user", required_argument, NULL, OPT_REPLICATION_USER},