github/repmgr
1
0
Fork 0
mirror of https://github.com/EnterpriseDB/repmgr.git synced 2026-03-22 22:56:29 +00:00
Code Issues Packages Projects Releases 1 Wiki Activity

Initial switchover implementation

Browse Source 
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
Download Patch File Download Diff File Expand all files Collapse all files

174
repmgr-action-node.c
View File

@@ -10,6 +10,8 @@
#include <dirent.h>
#include "repmgr.h"
#include "controldata.h"
#include "dirutil.h"
#include "repmgr-client-global.h"
#include "repmgr-action-node.h"
@@ -19,7 +21,8 @@ static void format_archive_dir(char *archive_dir);
static t_server_action parse_server_action(const char *action);
static void _do_node_service_check(void);
static void _do_node_service_list(t_server_action action);
static void _do_node_service_list_actions(t_server_action action);
static void _do_node_status_is_shutdown(void);
void
do_node_status(void)
@@ -39,6 +42,12 @@ do_node_status(void)
RecoveryType recovery_type;
ReplInfo replication_info = T_REPLINFO_INTIALIZER;
if (runtime_options.is_shutdown == true)
{
return _do_node_status_is_shutdown();
}
if (strlen(config_file_options.conninfo))
conn = establish_db_connection(config_file_options.conninfo, true);
else
@@ -59,6 +68,7 @@ do_node_status(void)
PQfinish(conn);
exit(ERR_BAD_CONFIG);
}
(void) get_server_version(conn, server_version);
if (get_cluster_size(conn, cluster_size) == false)
@@ -279,6 +289,92 @@ do_node_status(void)
}
/*
* --status=(RUNNING|SHUTDOWN|UNKNOWN)
* --last-checkpoint=...
*/
static
void _do_node_status_is_shutdown(void)
{
PGPing status;
PQExpBufferData output;
bool is_shutdown = true;
DBState db_state;
XLogRecPtr checkPoint;
initPQExpBuffer(&output);
appendPQExpBuffer(
&output,
"--state=");
/* sanity-check we're dealing with a PostgreSQL directory */
if (is_pg_dir(config_file_options.data_directory) == false)
{
appendPQExpBuffer(&output, "UNKNOWN");
printf("%s\n", output.data);
termPQExpBuffer(&output);
return;
}
status = PQping(config_file_options.conninfo);
switch (status)
{
case PQPING_OK:
appendPQExpBuffer(&output, "RUNNING");
is_shutdown = false;
break;
case PQPING_REJECT:
appendPQExpBuffer(&output, "RUNNING");
is_shutdown = false;
break;
case PQPING_NO_ATTEMPT:
case PQPING_NO_RESPONSE:
/* status not yet clear */
break;
}
/* check what pg_controldata says */
db_state = get_db_state(config_file_options.data_directory);
if (db_state != DB_SHUTDOWNED && db_state != DB_SHUTDOWNED_IN_RECOVERY)
{
appendPQExpBuffer(&output, "RUNNING");
is_shutdown = false;
}
checkPoint = get_latest_checkpoint_location(config_file_options.data_directory);
/* unable to read pg_control, don't know what's happening */
if (checkPoint == InvalidXLogRecPtr)
{
appendPQExpBuffer(&output, "UNKNOWN");
is_shutdown = false;
}
/* server is running in some state - just output --status */
if (is_shutdown == false)
{
printf("%s\n", output.data);
termPQExpBuffer(&output);
return;
}
appendPQExpBuffer(&output,
"SHUTDOWN --last-checkpoint-lsn=%X/%X",
format_lsn(checkPoint));
printf("%s\n", output.data);
termPQExpBuffer(&output);
return;
}
void
do_node_check(void)
@@ -289,10 +385,15 @@ do_node_check(void)
// --action=...
// --check
// --list -> list what would be executed for each action, filter to --action
// --checkpoint must be run as superuser - check connection
void
do_node_service(void)
{
t_server_action action;
t_server_action action = ACTION_UNKNOWN;
char data_dir[MAXPGPATH] = "";
char command[MAXLEN] = "";
PQExpBufferData output;
action = parse_server_action(runtime_options.action);
@@ -312,23 +413,66 @@ do_node_service(void)
return _do_node_service_check();
}
if (runtime_options.list == true)
if (runtime_options.list_actions == true)
{
return _do_node_service_list(action);
return _do_node_service_list_actions(action);
}
// do we need data directory?
// - service command defined for action ? -> no
// -> yes
// - pgdata defined in config? OK
//
// - connection available?
// -> get data dir OK (superuser connection issue)
if (data_dir_required_for_action(action))
{
get_node_data_directory(data_dir);
if (data_dir[0] == '\0')
{
log_error(_("unable to determine data directory for action"));
exit(ERR_BAD_CONFIG);
}
}
// perform action...
// --dry-run: print only
if ((action == ACTION_STOP || action == ACTION_RESTART) && runtime_options.checkpoint == true)
{
if (runtime_options.dry_run == true)
{
log_info(_("a CHECKPOINT would be issued here"));
}
else
{
PGconn *conn;
if (strlen(config_file_options.conninfo))
conn = establish_db_connection(config_file_options.conninfo, true);
else
conn = establish_db_connection_by_params(&source_conninfo, true);
log_notice(_("issuing CHECKPOINT"));
// check superuser conn!
checkpoint(conn);
PQfinish(conn);
}
}
get_server_action(action, command, data_dir);
if (runtime_options.dry_run == true)
{
log_info(_("would execute server command \"%s\""), command);
return;
}
log_notice(_("executing server command \"%s\""), command);
initPQExpBuffer(&output);
if (local_command(command, &output) == false)
{
exit(ERR_LOCAL_COMMAND);
}
termPQExpBuffer(&output);
}
@@ -339,7 +483,7 @@ _do_node_service_check(void)
static void
_do_node_service_list(t_server_action action)
_do_node_service_list_actions(t_server_action action)
{
char command[MAXLEN] = "";
@@ -644,6 +788,8 @@ do_node_restore_config(void)
}
static void
format_archive_dir(char *archive_dir)
{