standby clone: honour --waldir setting when cloning from Barman

By setting --waldir in "pg_basebackup_options", standbys cloned using
pg_basebackup would have their WAL directory set to the specified
location and symlinked from the data directory.

This commit causes repmgr to honour that setting even when cloning
from Barman.

HISTORY

@@ -5,6 +5,8 @@
         repmgr: "primary unregister --force" will unregister an active primary
           with no registered standby nodes (Ian)
         repmgr: add option --verify-backup to "standby clone" (Ian)
+        repmgr: "standby clone" honours --waldir option if set in
+          "pg_basebackup_options" (Ian)
         repmgr: add option --db-connection to "node check" (Ian)
         repmgr: report database connection error if the --optformat option was
           provided to "node check" (Ian)

doc/appendix-faq.xml

@@ -350,6 +350,9 @@
         and earlier) with the absolute path to the WAL directory in <varname>pg_basebackup_options</varname>.
         For more details see <xref linkend="cloning-advanced-pg-basebackup-options"/>.
       </para>
+      <para>
+        In &repmgr; 5.2 and later, this setting will also be honoured when cloning from Barman.
+      </para>
     </sect2>
 
     <sect2 id="faq-repmgr-events-no-fkey" xreflabel="No foreign key on node_id in repmgr.events">

doc/appendix-release-notes.xml

@@ -82,6 +82,18 @@
             </para>
           </listitem>
 
+          <listitem>
+            <para>
+              <link linkend="repmgr-standby-clone">repmgr standby clone</link>:
+              when cloning from Barman, setting <option>--waldir</option>
+              (PostgreSQL 9.6 and earlier: <option>--xlogdir</option>) in
+              <option>pg_basebackup_options</option> will cause &repmgr; to create
+              a WAL directory outside of the main data directory and symlink
+              it from there, in the same way as would happen when cloning
+              using <application>pg_basebackup</application>.
+            </para>
+          </listitem>
+
           <listitem>
             <para>
               <link linkend="repmgr-standby-follow">repmgr standby follow</link>:

doc/cloning-standbys.xml

@@ -148,6 +148,15 @@ description = "Main cluster"
       section in <command>man 5 ssh_config</command> for more details.
     </simpara>
    </tip>
+   <para>
+     If you wish to place WAL files in a location outside the main
+     PostgreSQL data directory, set <option>--waldir</option>
+     (PostgreSQL 9.6 and earlier: <option>--xlogdir</option>) in
+     <option>pg_basebackup_options</option> to the target directory
+     (must be an absolute filepath). &repmgr; will create and
+     symlink to this directory in exactly the same way
+     <application>pg_basebackup</application> would.
+   </para>
    <para>
     It's now possible to clone a standby from Barman, e.g.:
     <programlisting>
@@ -440,6 +449,13 @@ description = "Main cluster"
       WAL directory. Any WALs generated during the cloning process will be copied here, and
       a symlink will automatically be created from the main data directory.
     </para>
+    <tip>
+      <para>
+        The <literal>--waldir</literal> (<literal>--xlogdir</literal>) option,
+        if present in <varname>pg_basebackup_options</varname>, will be honoured by &repmgr;
+        when cloning from Barman (&repmgr; 5.2 and later).
+      </para>
+    </tip>
     <para>
      See the <ulink url="https://www.postgresql.org/docs/current/app-pgbasebackup.html">PostgreSQL pg_basebackup documentation</ulink>
      for more details of available options.

doc/repmgr-standby-clone.xml

@@ -191,6 +191,25 @@
    </note>
   </refsect1>
 
+  <refsect1 id="repmgr-standby-clone-wal-directory">
+
+   <title>Placing WAL files into a different directory</title>
+
+   <para>
+     To ensure that WAL files are placed in a directory outside of the main data
+     directory (e.g. to keep them on a separate disk for performance reasons),
+     specify the location with  <option>--waldir</option>
+     (PostgreSQL 9.6 and earlier: <option>--xlogdir</option>) in
+     the <filename>repmgr.conf</filename> parameter <option>pg_basebackup_options</option>,
+     e.g.:
+     <programlisting>
+pg_basebackup_options='--waldir=/path/to/wal-directory'</programlisting>
+     This setting will also be honored by &repmgr; when cloning from Barman
+     (&repmgr; 5.2 and later).
+   </para>
+
+  </refsect1>
+
 <!-- don't rename this id as it may be used in external links -->
   <refsect1 id="repmgr-standby-create-recovery-conf">
 

repmgr-action-standby.c

@@ -6941,9 +6941,20 @@ run_file_backup(t_node_info *local_node_record)
 
 	/* For the foreseeable future, no other modes are supported */
 	Assert(mode == barman);
-
 	if (mode == barman)
 	{
+		t_basebackup_options backup_options = T_BASEBACKUP_OPTIONS_INITIALIZER;
+
+		Assert(source_server_version_num != UNKNOWN_SERVER_VERSION_NUM);
+
+		/*
+		 * Parse the pg_basebackup_options provided in repmgr.conf - we need to
+		 * check if --waldir/--xlogdir was provided.
+		 */
+		parse_pg_basebackup_options(config_file_options.pg_basebackup_options,
+									&backup_options,
+									source_server_version_num,
+									NULL);
 		/*
 		 * Locate Barman's base backups directory
 		 */
@@ -7203,11 +7214,31 @@ run_file_backup(t_node_info *local_node_record)
 				if (vers[i] < 0 && source_server_version_num >= abs(vers[i]))
 					continue;
 
+				maxlen_snprintf(filename, "%s/%s", local_data_directory, dirs[i]);
+
 				/*
 				 * If --waldir/--xlogdir specified in "pg_basebackup_options",
 				 * create a symlink rather than make a directory.
 				 */
-				maxlen_snprintf(filename, "%s/%s", local_data_directory, dirs[i]);
+				if (strcmp(dirs[i], "pg_wal") == 0 || strcmp(dirs[i], "pg_xlog") == 0)
+				{
+					if (backup_options.waldir[0] != '\0')
+					{
+						if (create_pg_dir(backup_options.waldir, false) == false)
+						{
+							/* create_pg_dir() will log any errors */
+							exit(ERR_BAD_CONFIG);
+						}
+
+						if (symlink(backup_options.waldir, filename) != 0)
+						{
+							log_error(_("could not create symbolic link \"%s\""), filename);
+							exit(ERR_BAD_CONFIG);
+						}
+						continue;
+					}
+				}
+
 				if (mkdir(filename, S_IRWXU) != 0 && errno != EEXIST)
 				{
 					log_error(_("unable to create the %s directory"), dirs[i]);

repmgr.conf.sample

@@ -181,6 +181,8 @@
 
 #pg_ctl_options=''			# Options to append to "pg_ctl"
 #pg_basebackup_options=''		# Options to append to "pg_basebackup"
+                                        # (Note: when cloning from Barman, repmgr will honour any
+                                        # --waldir/--xlogdir setting present in "pg_basebackup_options"
 #rsync_options=''			# Options to append to "rsync"
 ssh_options='-q -o ConnectTimeout=10'	# Options to append to "ssh"