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"standby switchover": check demotion candidate can make replication connection

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Check it's actually possible for the demotion candidate to attach to
the promotion candidate before executing the switchover.

As with other checks of this nature, there's a faint possibility the
situation could change between the time the check is carried out and
the demotion candidate is restarted to connect to the promotion candidate,
but there's not a lot we can do about that. The main purpose is to
be able to catch existing misconfigurations before anything gets changed.

Implements GitHub #370.
This commit is contained in:
Ian Barwick
2018-02-08 16:59:30 +09:00
committed by Ian Barwick
parent 76a93af15c
commit 927bf038a0
6 changed files with 205 additions and 14 deletions
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119
repmgr-action-standby.c
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@@ -101,6 +101,7 @@ static bool write_recovery_file_line(FILE *recovery_file, char *recovery_file_pa
static NodeStatus parse_node_status_is_shutdown_cleanly(const char *node_status_output, XLogRecPtr *checkPoint);
static CheckStatus parse_node_check_archiver(const char *node_check_output, int *files, int *threshold);
static ConnectionStatus parse_remote_node_replication_connection(const char *node_check_output);
/*
* STANDBY CLONE
@@ -2373,8 +2374,7 @@ do_standby_switchover(void)
appendPQExpBuffer(&remote_command_str, "--version 2>/dev/null && echo \"1\" || echo \"0\"");
initPQExpBuffer(&command_output);
command_success = remote_command(
remote_host,
command_success = remote_command(remote_host,
runtime_options.remote_user,
remote_command_str.data,
&command_output);
@@ -2394,20 +2394,17 @@ do_standby_switchover(void)
termPQExpBuffer(&command_output);
initPQExpBuffer(&hint);
appendPQExpBuffer(
&hint,
appendPQExpBuffer(&hint,
_("check \"pg_bindir\" is set to the correct path in \"repmgr.conf\"; current value: "));
if (strlen(config_file_options.pg_bindir))
{
appendPQExpBuffer(
&hint,
appendPQExpBuffer(&hint,
"\"%s\"", config_file_options.pg_bindir);
}
else
{
appendPQExpBuffer(
&hint,
appendPQExpBuffer(&hint,
"(not set)");
}
@@ -2428,6 +2425,49 @@ do_standby_switchover(void)
}
termPQExpBuffer(&command_output);
/* check demotion candidate can make replication connection to promotion candidate */
{
initPQExpBuffer(&remote_command_str);
make_remote_repmgr_path(&remote_command_str, &remote_node_record);
appendPQExpBuffer(&remote_command_str,
"node check --remote-node-id=%i --replication-connection",
local_node_record.node_id);
initPQExpBuffer(&command_output);
command_success = remote_command(remote_host,
runtime_options.remote_user,
remote_command_str.data,
&command_output);
termPQExpBuffer(&remote_command_str);
if (command_success == true)
{
ConnectionStatus conn_status = parse_remote_node_replication_connection(command_output.data);
switch(conn_status)
{
case CONN_OK:
if (runtime_options.dry_run == true)
{
log_info(_("demotion candidate is able to make replication connection to promotion candidate"));
}
break;
case CONN_BAD:
log_error(_("demotion candidate is unable to make replication connection to promotion candidate"));
exit(ERR_BAD_CONFIG);
break;
default:
log_error(_("unable to deterimine whether candidate is able to make replication connection to promotion candidate"));
exit(ERR_BAD_CONFIG);
break;
}
termPQExpBuffer(&command_output);
}
}
/* check archive/replication status */
{
int lag_seconds = 0;
@@ -5447,6 +5487,69 @@ parse_node_status_is_shutdown_cleanly(const char *node_status_output, XLogRecPtr
}
static ConnectionStatus
parse_remote_node_replication_connection(const char *node_check_output)
{
ConnectionStatus conn_status = CONN_UNKNOWN;
int c = 0,
argc_item = 0;
char **argv_array = NULL;
int optindex = 0;
/* We're only interested in these options */
struct option node_check_options[] =
{
{"connection", required_argument, NULL, 'c'},
{NULL, 0, NULL, 0}
};
/* Don't attempt to tokenise an empty string */
if (!strlen(node_check_output))
{
return CONN_UNKNOWN;
}
argc_item = parse_output_to_argv(node_check_output, &argv_array);
/* Reset getopt's optind variable */
optind = 0;
/* Prevent getopt from emitting errors */
opterr = 0;
while ((c = getopt_long(argc_item, argv_array, "L:S:", node_check_options,
&optindex)) != -1)
{
switch (c)
{
/* --connection */
case 'c':
{
if (strncmp(optarg, "OK", MAXLEN) == 0)
{
conn_status = CONN_OK;
}
else if (strncmp(optarg, "BAD", MAXLEN) == 0)
{
conn_status = CONN_BAD;
}
else if (strncmp(optarg, "UNKNOWN", MAXLEN) == 0)
{
conn_status = CONN_UNKNOWN;
}
}
break;
}
}
free_parsed_argv(&argv_array);
return conn_status;
}
static CheckStatus
parse_node_check_archiver(const char *node_check_output, int *files, int *threshold)
{