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Initial switchover implementation

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The repmgr3 implementation required the promotion candidate (standby)
to directly work with the demotion candidate's data directory,
directly execute server control commands etc.

Here we delegated a lot more of that work to the repmgr on the
demotion candidate, which reduces the amount of back-and-forth
over SSH and generally makes things cleaner and smoother.

In particular the repmgr on the demotion candidate will carry
out a thorough check that the node is shut down and report
the last checkpoint LSN to the promotion candidate; this
can then be used to determine whether pg_rewind needs to be
executed on the demoted primary before reintegrating it back
into the cluster (todo).

Also implement "--dry-run" for this action, which will sanity-check the
nodes as far as possible without executing the switchover.

Additionally some of the new repmgr node commands (or command options)
introduced for this can be also executed by the user to obtain
additional information about the status of each node.
This commit is contained in:
Ian Barwick
2017-08-03 16:38:37 +09:00
parent c67aa15581
commit 112ca6321a
15 changed files with 1024 additions and 102 deletions
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124
repmgr-client.c
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@@ -15,6 +15,7 @@
* STANDBY REGISTER
* STANDBY UNREGISTER
* STANDBY PROMOTE
* STANDBY SWITCHOVER
*
* BDR REGISTER
* BDR UNREGISTER
@@ -156,7 +157,7 @@ main(int argc, char **argv)
strncpy(runtime_options.username, pw->pw_name, MAXLEN);
}
while ((c = getopt_long(argc, argv, "?Vb:f:Fd:h:p:U:R:S:L:vtD:cr", long_options,
while ((c = getopt_long(argc, argv, "?Vb:f:Fd:h:p:U:R:S:L:vtD:crC:", long_options,
&optindex)) != -1)
{
/*
@@ -320,13 +321,15 @@ main(int argc, char **argv)
{
runtime_options.copy_external_config_files_destination = CONFIG_FILE_SAMEPATH;
}
else if (strcmp(optarg, "pgdata") == 0)
/* allow "data_directory" as synonym for "pgdata" */
else if (strcmp(optarg, "pgdata") == 0 || strcmp(optarg, "data_directory") == 0)
{
runtime_options.copy_external_config_files_destination = CONFIG_FILE_PGDATA;
}
else
{
item_list_append(&cli_errors, _("value provided for '--copy-external-config-files' must be 'samepath' or 'pgdata'"));
item_list_append(&cli_errors,
_("value provided for \"--copy-external-config-files\" must be \"samepath\" or \"pgdata\""));
}
}
break;
@@ -395,6 +398,28 @@ main(int argc, char **argv)
}
break;
/* "standby switchover" options *
* ---------------------------- */
case 'C':
strncpy(runtime_options.remote_config_file, optarg, MAXPGPATH);
break;
case OPT_ALWAYS_PROMOTE:
runtime_options.always_promote = true;
break;
case OPT_FORCE_REWIND:
runtime_options.force_rewind = true;
break;
/* "node status" options *
* --------------------- */
case OPT_IS_SHUTDOWN:
runtime_options.is_shutdown = true;
break;
/* "node service" options *
* ---------------------- */
@@ -403,14 +428,18 @@ main(int argc, char **argv)
strncpy(runtime_options.action, optarg, MAXLEN);
break;
case OPT_LIST:
runtime_options.list = true;
case OPT_LIST_ACTIONS:
runtime_options.list_actions = true;
break;
case OPT_CHECK:
runtime_options.check = true;
break;
case OPT_CHECKPOINT:
runtime_options.checkpoint = true;
break;
/* "cluster event" options *
* ----------------------- */
@@ -1122,16 +1151,7 @@ check_cli_parameters(const int action)
/*
* if `repmgr standby follow` executed with host params, ensure data
* directory was provided
* XXX not needed
*/
if (runtime_options.host_param_provided == true)
{
if (runtime_options.data_dir[0] == '\0')
{
item_list_append_format(&cli_errors,
_("-D/--pgdata required when providing connection parameters for \"standby follow\""));
}
}
}
break;
@@ -1315,7 +1335,7 @@ check_cli_parameters(const int action)
}
/* repmgr node service --action */
if (runtime_options.action)
if (runtime_options.action[0] != '\0')
{
switch (action)
{
@@ -1323,10 +1343,52 @@ check_cli_parameters(const int action)
break;
default:
item_list_append_format(&cli_warnings,
_("--action not required when executing %s"),
_("--action will be ignored when executing %s"),
action_name(action));
}
}
/* repmgr node status --is-shutdown */
if (runtime_options.is_shutdown == true)
{
switch (action)
{
case NODE_STATUS:
break;
default:
item_list_append_format(&cli_warnings,
_("--is-shutdown will be ignored when executing %s"),
action_name(action));
}
}
if (runtime_options.always_promote == true)
{
switch (action)
{
case STANDBY_SWITCHOVER:
break;
default:
item_list_append_format(&cli_warnings,
_("--always-promote will be ignored when executing %s"),
action_name(action));
}
}
if ( runtime_options.force_rewind == true)
{
switch (action)
{
case STANDBY_SWITCHOVER:
break;
default:
item_list_append_format(&cli_warnings,
_("--force-rewind will be ignored when executing %s"),
action_name(action));
}
}
}
@@ -1461,7 +1523,7 @@ do_help(void)
puts("");
printf(_("CLUSTER SHOW options:\n"));
printf(_("CLUSTER EVENT options:\n"));
printf(_(" --limit maximum number of events to display (default: %i)\n"), CLUSTER_EVENT_LIMIT);
printf(_(" --all display all events (overrides --limit)\n"));
printf(_(" --event filter specific event\n"));
@@ -1706,8 +1768,8 @@ test_ssh_connection(char *host, char *remote_user)
/*
* Execute a command locally. If outputbuf == NULL, discard the
* output.
* Execute a command locally. "outputbuf" should either be an
* initialised PQexpbuffer, or NULL
*/
bool
local_command(const char *command, PQExpBufferData *outputbuf)
@@ -2496,7 +2558,7 @@ remote_command(const char *host, const char *user, const char *command, PQExpBuf
appendPQExpBuffer(&ssh_host, "%s@", user);
}
appendPQExpBuffer(&ssh_host, "%s",host);
appendPQExpBuffer(&ssh_host, "%s", host);
maxlen_snprintf(ssh_command,
"ssh -o Batchmode=yes %s %s %s",
@@ -2506,7 +2568,7 @@ remote_command(const char *host, const char *user, const char *command, PQExpBuf
termPQExpBuffer(&ssh_host);
log_debug("remote_command(): %s\n", ssh_command);
log_debug("remote_command():\n %s", ssh_command);
fp = popen(ssh_command, "r");
@@ -2549,6 +2611,20 @@ remote_command(const char *host, const char *user, const char *command, PQExpBuf
}
void
make_remote_repmgr_path(PQExpBufferData *output_buf)
{
appendPQExpBuffer(output_buf,
"%s ", make_pg_path("repmgr"));
if (runtime_options.remote_config_file[0] != '\0')
{
appendPQExpBuffer(output_buf,
"-f %s ", runtime_options.remote_config_file);
}
}
/* ======================== */
/* server control functions */
/* ======================== */
@@ -2786,15 +2862,13 @@ data_dir_required_for_action(t_server_action action)
void
get_node_data_directory(char *data_dir_buf)
{
PGconn *conn = NULL;
/*
* the configuration file setting has priority, and will always be
* set when a configuration file was provided
*/
if (config_file_options.pgdata[0] != '\0')
if (config_file_options.data_directory[0] != '\0')
{
strncpy(data_dir_buf, config_file_options.pgdata, MAXPGPATH);
strncpy(data_dir_buf, config_file_options.data_directory, MAXPGPATH);
return;
}