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"standby switchover": improve log messages and add new exit code

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Previously, if an issue was encountered with the old primary, but user
provided -F/--force to have repmgr promote the standby anyway, repmgr
would exit with the log message "STANDBY SWITCHOVER is complete"
and exit code 0 (SUCCESS).

To better report this partial completion, repmgr will now emit the message
"STANDBY SWITCHOVER has completed with issues" (and a HINT to check preceding
log messages) and new exit code 22 (ERR_SWITCHOVER_INCOMPLETE).
This commit is contained in:
Ian Barwick
2018-01-31 10:25:15 +09:00
parent 2eec8b5d79
commit c0a53471e1
4 changed files with 100 additions and 12 deletions
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4
HISTORY
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@@ -1,8 +1,10 @@
4.0.3 2018-02-
repmgr: improve switchover handling when "pg_ctl" used to control the
server and logging output is not explicitly redirected (Ian)
repmgr: improve switchover log messages and exit code when old primary could
not be shut down cleanly (Ian)
4.0.2 2018-01-
4.0.2 2018-01-18
repmgr: add missing -W option to getopt_long() invocation; GitHub #350 (Ian)
repmgr: automatically create slot name if missing; GitHub #343 (Ian)
repmgr: fixes to parsing output of remote repmgr invocations; GitHub #349 (Ian)

66
doc/repmgr-standby-switchover.sgml
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@@ -22,9 +22,17 @@
</para>
<para>
If other standbys are connected to the demotion candidate, &repmgr; can instruct
these to follow the new primary if the option <literal>--siblings-follow</literal>
these to follow the new primary if the option <literal>--siblings-follow</literal>
is specified.
</para>
<note>
<para>
Performing a switchover is a non-trivial operation. In particular it
relies on the current primary being able to shut down cleanly and quickly.
&repmgr; will attempt to check for potential issues but cannot guarantee
a successful switchover.
</para>
</note>
</refsect1>
<refsect1>
@@ -47,6 +55,13 @@
<para>
Check prerequisites but don't actually execute a switchover.
</para>
<important>
<para>
Success of <option>--dry-run</option> does not imply the switchover will
complete successfully, only that
the prerequisites for performing the operation are met.
</para>
</important>
</listitem>
</varlistentry>
@@ -57,6 +72,12 @@
<para>
Ignore warnings and continue anyway.
</para>
<para>
Specifically, if a problem is encountered when shutting down the current primary,
using <option>-F/--force</option> will cause &repmgr; to continue by promoting
the standby to be the new primary, and if <option>--siblings-follow</option> is
specified, attach any other standbys to the new primary.
</para>
</listitem>
</varlistentry>
@@ -103,6 +124,11 @@
<application>repmgrd</application> should not be active on any nodes while a switchover is being
executed. This restriction may be lifted in a later version.
</para>
<para>
External database connections, e.g. from an application, should not be permitted while
the switchover is taking place. In particular, active transactions on the primary
can potentially disrupt the shutdown process.
</para>
</refsect1>
<refsect1>
@@ -119,6 +145,44 @@
</para>
</refsect1>
<refsect1>
<title>Exit codes</title>
<para>
Following exit codes can be emitted by <literal>repmgr standby switchover</literal>:
</para>
<variablelist>
<varlistentry>
<term><option>SUCCESS (0)</option></term>
<listitem>
<para>
The switchover completed successfully.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>ERR_SWITCHOVER_FAIL (18)</option></term>
<listitem>
<para>
The switchover could not be executed.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>ERR_SWITCHOVER_INCOMPLETE (22)</option></term>
<listitem>
<para>
The switchover was executed but a problem was encountered.
Typically this means the former primary could not be reattached
as a standby.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>See also</title>

2
errcode.h
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@@ -43,6 +43,6 @@
#define ERR_BARMAN 19
#define ERR_REGISTRATION_SYNC 20
#define ERR_OUT_OF_MEMORY 21
#define ERR_REJOIN_FAIL 22
#define ERR_SWITCHOVER_INCOMPLETE 22
#endif /* _ERRCODE_H_ */

40
repmgr-action-standby.c
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@@ -2036,6 +2036,10 @@ do_standby_switchover(void)
i;
bool command_success = false;
bool shutdown_success = false;
/* this flag will use to generate the final message generated */
bool switchover_success = true;
XLogRecPtr remote_last_checkpoint_lsn = InvalidXLogRecPtr;
ReplInfo replication_info = T_REPLINFO_INTIALIZER;
@@ -2894,12 +2898,17 @@ do_standby_switchover(void)
/* clean up remote node */
remote_conn = establish_db_connection(remote_node_record.conninfo, false);
/* check replication status */
/* check new standby (old primary) is reachable */
if (PQstatus(remote_conn) != CONNECTION_OK)
{
log_error(_("unable to reestablish connection to remote node \"%s\""),
remote_node_record.node_name);
/* log_hint(_("")); // depends on replication status */
switchover_success = false;
/* TODO: double-check whether new standby has attached */
log_warning(_("switchover did not fully complete"));
log_detail(_("node \"%s\" is now primary but node \"%s\" is not reachable"),
local_node_record.node_name,
remote_node_record.node_name);
}
else
{
@@ -2910,17 +2919,20 @@ do_standby_switchover(void)
local_node_record.slot_name);
}
/* TODO warn about any inactive replication slots */
log_notice(_("switchover was successful"));
log_detail(_("node \"%s\" is now primary and node \"%s\" is attached as standby"),
local_node_record.node_name,
remote_node_record.node_name);
}
PQfinish(remote_conn);
log_notice(_("switchover was successful"));
log_detail(_("node \"%s\" is now primary"),
local_node_record.node_name);
/*
* If --siblings-follow specified, attempt to make them follow the new
* standby
* primary
*/
if (runtime_options.siblings_follow == true && sibling_nodes.node_count > 0)
@@ -2993,7 +3005,17 @@ do_standby_switchover(void)
PQfinish(local_conn);
log_notice(_("STANDBY SWITCHOVER is complete"));
if (switchover_success == true)
{
log_notice(_("STANDBY SWITCHOVER has completed successfully"));
}
else
{
log_notice(_("STANDBY SWITCHOVER has completed with issues"));
log_hint(_("see preceding log message(s) for details"));
exit(ERR_SWITCHOVER_INCOMPLETE);
}
return;
}