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repmgrd: restrict BDR monitoring to two node setup

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It's not safe to have more than two nodes with this kind of
"failover", so we don't need to select alternative nodes by
priority.
This commit is contained in:
Ian Barwick
2017-07-14 12:56:11 +09:00
parent 91c7013024
commit e3b3fb65f0
12 changed files with 96 additions and 212 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
config.c
View File

@@ -435,23 +435,6 @@ _parse_config(t_configuration_options *options, ItemList *error_list, ItemList *
else if (strcmp(name, "event_notifications") == 0)
parse_event_notifications_list(options, value);
/* bdr settings */
else if (strcmp(name, "bdr_monitoring_mode") == 0)
{
if (strncmp(value, "local", MAXLEN) == 0)
{
options->bdr_monitoring_mode = BDR_MONITORING_LOCAL;
}
else if (strcmp(value, "highest_priority") == 0)
{
options->bdr_monitoring_mode = BDR_MONITORING_PRIORITY;
}
else
{
item_list_append(error_list, _("value for 'bdr_monitoring_mode' must be 'local' or 'highest_priority'\n"));
}
}
/* barman settings */
else if (strcmp(name, "barman_host") == 0)
strncpy(options->barman_host, value, MAXLEN);

5
config.h
View File

@@ -97,9 +97,6 @@ typedef struct
char event_notification_command[MAXLEN];
EventNotificationList event_notifications;
/* bdr settings */
int bdr_monitoring_mode;
/* barman settings */
char barman_host[MAXLEN];
char barman_server[MAXLEN];
@@ -132,8 +129,6 @@ typedef struct
"", "", "", "", "", "", \
/* event notification settings */ \
"", { NULL, NULL }, \
/* bdr settings */ \
BDR_MONITORING_LOCAL, \
/* barman settings */ \
"", "", "", \
/* undocumented test settings */ \

23
dbutils.c
View File

@@ -14,6 +14,11 @@
#include "catalog/pg_control.h"
/* mainly for use by repmgrd */
int server_version_num = 0;
static PGconn *_establish_db_connection(const char *conninfo,
const bool exit_on_error,
const bool log_notice,
@@ -1501,8 +1506,6 @@ get_active_sibling_node_records(PGconn *conn, int node_id, int upstream_node_id,
PQExpBufferData query;
PGresult *res;
clear_node_info_list(node_list);
initPQExpBuffer(&query);
appendPQExpBuffer(&query,
@@ -1535,8 +1538,6 @@ get_node_records_by_priority(PGconn *conn, NodeInfoList *node_list)
PQExpBufferData query;
PGresult *res;
clear_node_info_list(node_list);
initPQExpBuffer(&query);
appendPQExpBuffer(
@@ -1696,7 +1697,7 @@ update_node_record_set_active(PGconn *conn, int this_node_id, bool active)
appendPQExpBuffer(
&query,
"UPDATE repmgr.nodes SET active = %s "
" WHERE id = %i",
" WHERE node_id = %i",
active == true ? "TRUE" : "FALSE",
this_node_id);
@@ -1878,7 +1879,7 @@ update_node_record_conn_priority(PGconn *conn, t_configuration_options *options)
"UPDATE repmgr.nodes "
" SET conninfo = '%s', "
" priority = %d "
" WHERE id = %d ",
" WHERE node_id = %d ",
options->conninfo,
options->priority,
options->node_id);
@@ -1929,14 +1930,13 @@ delete_node_record(PGconn *conn, int node)
}
void
clear_node_info_list(NodeInfoList *nodes)
{
NodeInfoListCell *cell;
NodeInfoListCell *next_cell;
log_debug("clear_node_info_list() - closing open connections");
log_verbose(LOG_DEBUG, "clear_node_info_list() - closing open connections");
/* close any open connections */
for (cell = nodes->head; cell; cell = cell->next)
@@ -1948,7 +1948,7 @@ clear_node_info_list(NodeInfoList *nodes)
}
}
log_debug("clear_node_info_list() - unlinking");
log_verbose(LOG_DEBUG, "clear_node_info_list() - unlinking");
cell = nodes->head;
@@ -1959,6 +1959,7 @@ clear_node_info_list(NodeInfoList *nodes)
pfree(cell);
cell = next_cell;
}
nodes->head = NULL;
nodes->tail = NULL;
nodes->node_count = 0;
@@ -3134,9 +3135,7 @@ void _populate_bdr_node_records(PGresult *res, BdrNodeInfoList *node_list)
{
int i;
node_list->head = NULL;
node_list->tail = NULL;
node_list->node_count = 0;
clear_node_info_list(node_list);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{

3
dbutils.h
View File

@@ -186,6 +186,9 @@ typedef struct BdrNodeInfoList
0 \
}
extern int server_version_num;
/* utility functions */
XLogRecPtr parse_lsn(const char *str);

10
repmgr-client.c
View File

@@ -1467,12 +1467,12 @@ create_repmgr_extension(PGconn *conn)
int
check_server_version(PGconn *conn, char *server_type, bool exit_on_error, char *server_version_string)
{
int server_version_num = 0;
int conn_server_version_num = 0;
server_version_num = get_server_version(conn, server_version_string);
if (server_version_num < MIN_SUPPORTED_VERSION_NUM)
conn_server_version_num = get_server_version(conn, server_version_string);
if (conn_server_version_num < MIN_SUPPORTED_VERSION_NUM)
{
if (server_version_num > 0)
if (conn_server_version_num > 0)
log_error(_("%s requires %s to be PostgreSQL %s or later"),
progname(),
server_type,
@@ -1488,7 +1488,7 @@ check_server_version(PGconn *conn, char *server_type, bool exit_on_error, char *
return -1;
}
return server_version_num;
return conn_server_version_num;
}

6
repmgr.conf.sample
View File

@@ -13,7 +13,7 @@
# repmgr and repmgrd require the following items to be configured.
#node_id=1 # A unique integer greater than zero
#node_id= # A unique integer greater than zero
#node_name='' # An arbitrary (but unique) string; we recommend
# using the server's hostname or another identifier
# unambiguously associated with the server to avoid
@@ -28,6 +28,7 @@
#
# For details on conninfo strings, see:
# https://www.postgresql.org/docs/current/static/libpq-connect.html#LIBPQ-CONNSTRING
#
# If repmgrd is in use, consider explicitly setting
# "connect_timeout" in the conninfo string to determine
# the length of time which elapses before a network
@@ -44,8 +45,9 @@
# Replication settings
#------------------------------------------------------------------------------
#replication_type=physical # Must be one of 'physical' or 'bdr'
#upstream_node_id=1 # When using cascading replication, a standby
#upstream_node_id= # When using cascading replication, a standby
# can connect to another upstream standby node
# which is specified by setting 'upstream_node_id'.
# In that case, the upstream node must exist

3
repmgr.h
View File

@@ -30,8 +30,6 @@
#define REPLICATION_TYPE_PHYSICAL 1
#define REPLICATION_TYPE_BDR 2
#define BDR_MONITORING_LOCAL 1
#define BDR_MONITORING_PRIORITY 2
#define DEFAULT_LOCATION "default"
#define DEFAULT_PRIORITY 100
@@ -52,4 +50,5 @@
#define ERRBUFF_SIZE 512
#endif /* _REPMGR_H_ */

231
repmgrd-bdr.c
View File

@@ -14,6 +14,9 @@
static volatile sig_atomic_t got_SIGHUP = false;
static void do_bdr_failover(NodeInfoList *nodes);
void
do_bdr_node_check(void)
{
@@ -25,12 +28,8 @@ void
monitor_bdr(void)
{
NodeInfoList nodes = T_NODE_INFO_LIST_INITIALIZER;
PGconn *monitoring_conn = NULL;
t_node_info *monitored_node = NULL;
t_bdr_node_info bdr_node_info = T_BDR_NODE_INFO_INITIALIZER;
RecordStatus record_status;
bool failover_done = false;
/* sanity check local database */
log_info(_("connecting to local database '%s'"),
@@ -118,7 +117,6 @@ monitor_bdr(void)
}
/* Log startup event */
create_event_record(local_conn,
&config_file_options,
config_file_options.node_id,
@@ -128,158 +126,72 @@ monitor_bdr(void)
/*
* retrieve list of nodes - we'll need these if the DB connection goes away,
* or if we're monitoring a non-local node
*/
get_node_records_by_priority(local_conn, &nodes);
get_all_node_records(local_conn, &nodes);
/* decided which node to monitor */
log_debug("main_loop_bdr() monitoring local node %i", config_file_options.node_id);
if (config_file_options.bdr_monitoring_mode == BDR_MONITORING_LOCAL)
{
// if local, reuse local_conn and node info
//record_status = get_node_record(local_conn, config_file_options.node_id, &monitored_node);
monitored_node = &local_node_info;
monitoring_conn = establish_db_connection(monitored_node->conninfo, false);
log_debug("main_loop_bdr() monitoring local node %i", config_file_options.node_id);
}
else
{
NodeInfoListCell *cell;
for (cell = nodes.head; cell; cell = cell->next)
{
log_debug("main_loop_bdr() checking node %s %i", cell->node_info->node_name, cell->node_info->priority);
monitoring_conn = establish_db_connection(cell->node_info->conninfo, false);
if (PQstatus(monitoring_conn) == CONNECTION_OK)
{
log_debug("main_loop_bdr() monitoring node '%s' (ID %i, priority %i)",
cell->node_info->node_name, cell->node_info->node_id, cell->node_info->priority);
/* fetch the record again, as the node list is transient */
monitored_node = get_node_record_pointer(monitoring_conn, cell->node_info->node_id);
break;
}
}
}
// check monitored_node not null!
log_info(_("starting continuous bdr node monitoring"));
while (true)
{
/* normal state - connection active */
if (PQstatus(monitoring_conn) == CONNECTION_OK)
/* monitoring loop */
log_verbose(LOG_DEBUG, "bdr check loop...");
switch (monitoring_state)
{
// XXX detail
log_info(_("starting continuous bdr node monitoring"));
/* monitoring loop */
do
case MS_NORMAL:
{
log_verbose(LOG_DEBUG, "bdr check loop...");
if (is_server_available(local_node_info.conninfo) == false)
{
NodeInfoListCell *cell;
for (cell = nodes.head; cell; cell = cell->next)
{
log_debug("bdr_monitor() %s", cell->node_info->node_name);
}
}
if (is_server_available(monitored_node->conninfo) == false)
{
t_node_info *new_monitored_node;
// XXX improve
log_warning("connection problem!");
new_monitored_node = do_bdr_failover(&nodes, monitored_node);
if (new_monitored_node != NULL)
{
pfree(monitored_node);
monitored_node = new_monitored_node;
}
log_notice(_("monitored_node->node_name is now '%s' \n"), monitored_node->node_name);
do_bdr_failover(&nodes);
}
else
{
log_verbose(LOG_DEBUG, "sleeping %i seconds (\"monitor_interval_secs\")",
config_file_options.monitor_interval_secs);
sleep(config_file_options.monitor_interval_secs);
}
if (got_SIGHUP)
{
/*
* if we can reload, then could need to change
* local_conn
*/
if (reload_config(&config_file_options))
{
PQfinish(local_conn);
local_conn = establish_db_connection(config_file_options.conninfo, true);
update_registration(local_conn);
}
/* reload node list */
get_node_records_by_priority(local_conn, &nodes);
got_SIGHUP = false;
}
} while (!failover_done);
}
/* local connection inactive - periodically try and connect */
/* TODO: make this an option */
else
{
monitoring_conn = establish_db_connection(monitored_node->conninfo, false);
if (PQstatus(monitoring_conn) == CONNECTION_OK)
}
case MS_DEGRADED:
{
// XXX event bdr_node_recovered -> if monitored == local node
if (monitored_node->node_id == config_file_options.node_id)
/* degraded monitoring */
if (is_server_available(local_node_info.conninfo) == true)
{
log_notice(_("local connection has returned, resuming monitoring"));
log_notice(_("monitored node %i has recovered"), local_node_info.node_id);
// do_bdr_recovery()
}
else
{
log_notice(_("connection to '%s' has returned, resuming monitoring"), monitored_node->node_name);
log_verbose(LOG_DEBUG, "sleeping %i seconds (\"monitor_interval_secs\")",
config_file_options.monitor_interval_secs);
sleep(config_file_options.monitor_interval_secs);
}
}
else
{
sleep(config_file_options.monitor_interval_secs);
}
if (got_SIGHUP)
{
/*
* if we can reload, then could need to change
* local_conn
*/
if (reload_config(&config_file_options))
{
if (PQstatus(local_conn) == CONNECTION_OK)
{
PQfinish(local_conn);
local_conn = establish_db_connection(config_file_options.conninfo, true);
update_registration(local_conn);
}
}
/* reload node list */
if (PQstatus(local_conn) == CONNECTION_OK)
get_node_records_by_priority(local_conn, &nodes);
got_SIGHUP = false;
}
}
failover_done = false;
if (got_SIGHUP)
{
/*
* if we can reload, then could need to change
* local_conn
*/
if (reload_config(&config_file_options))
{
PQfinish(local_conn);
local_conn = establish_db_connection(config_file_options.conninfo, true);
update_registration(local_conn);
}
/* reload node list */
get_all_node_records(local_conn, &nodes);
got_SIGHUP = false;
}
}
return;
@@ -294,43 +206,44 @@ monitor_bdr(void)
* we'll do the following:
*
* - attempt to find another node, to set our node record as inactive
* (there should be only one other node)
* - generate an event log record on that node
* - optionally execute `bdr_failover_command`, passing the conninfo string
* of that node to the command; this can be used for e.g. reconfiguring
* pgbouncer.
* - if mode is 'BDR_MONITORING_PRIORITY', redirect monitoring to that node.
*
*/
t_node_info *
do_bdr_failover(NodeInfoList *nodes, t_node_info *monitored_node)
void
do_bdr_failover(NodeInfoList *nodes)
{
PGconn *next_node_conn = NULL;
NodeInfoListCell *cell;
bool failover_success = false;
PQExpBufferData event_details;
RecordStatus record_status;
t_event_info event_info = T_EVENT_INFO_INITIALIZER;
t_node_info *new_monitored_node = NULL;
t_node_info target_node = T_NODE_INFO_INITIALIZER;
initPQExpBuffer(&event_details);
/* get next active priority node */
/* get next active node */
for (cell = nodes->head; cell; cell = cell->next)
{
log_debug("do_bdr_failover() %s", cell->node_info->node_name);
/* don't attempt to connect to the current monitored node, as that's the one which has failed */
if (cell->node_info->node_id == monitored_node->node_id)
if (cell->node_info->node_id == local_node_info.node_id)
continue;
/* XXX skip inactive node? */
next_node_conn = establish_db_connection(cell->node_info->conninfo, false);
if (PQstatus(next_node_conn) == CONNECTION_OK)
{
// XXX check if record returned
new_monitored_node = get_node_record_pointer(next_node_conn, cell->node_info->node_id);
record_status = get_node_record(next_node_conn, cell->node_info->node_id, &target_node);
break;
}
@@ -345,40 +258,34 @@ do_bdr_failover(NodeInfoList *nodes, t_node_info *monitored_node)
log_error("%s", event_details.data);
// no other nodes found
// continue degraded monitoring until node is restored?
}
else
{
log_info(_("connecting to target node %s"), cell->node_info->node_name);
log_info(_("connecting to target node %s"), target_node.node_name);
failover_success = true;
event_info.conninfo_str = cell->node_info->conninfo;
event_info.node_name = cell->node_info->node_name;
event_info.conninfo_str = target_node.conninfo;
event_info.node_name = target_node.node_name;
/* update our own record on the other node */
if (monitored_node->node_id == config_file_options.node_id)
{
update_node_record_set_active(next_node_conn, monitored_node->node_id, false);
}
if (config_file_options.bdr_monitoring_mode == BDR_MONITORING_PRIORITY)
{
log_notice(_("monitoring next available node by prioriy: %s (ID %i)"),
new_monitored_node->node_name,
new_monitored_node->node_id);
}
update_node_record_set_active(next_node_conn, local_node_info.node_id, false);
appendPQExpBuffer(&event_details,
_("node '%s' (ID: %i) detected as failed; next available node is '%s' (ID: %i)"),
monitored_node->node_name,
monitored_node->node_id,
cell->node_info->node_name,
cell->node_info->node_id);
local_node_info.node_name,
local_node_info.node_id,
target_node.node_name,
target_node.node_id);
}
monitoring_state = MS_DEGRADED;
INSTR_TIME_SET_CURRENT(degraded_monitoring_start);
// check here that the node hasn't come back up...
/*
* Create an event record
*
@@ -400,11 +307,7 @@ do_bdr_failover(NodeInfoList *nodes, t_node_info *monitored_node)
termPQExpBuffer(&event_details);
//failover_done = true;
if (config_file_options.bdr_monitoring_mode == BDR_MONITORING_PRIORITY)
return new_monitored_node;
/* local monitoring mode - there's no new node to monitor */
return NULL;
return;
}

1
repmgrd-bdr.h
View File

@@ -8,6 +8,5 @@
extern void do_bdr_node_check(void);
extern void monitor_bdr(void);
extern t_node_info *do_bdr_failover(NodeInfoList *nodes, t_node_info *monitored_node);
#endif /* _REPMGRD_BDR_H_ */

6
repmgrd-physical.c
View File

@@ -325,7 +325,11 @@ monitor_streaming_primary(void)
INSTR_TIME_SET_CURRENT(log_status_interval_start);
}
}
sleep(1);
log_verbose(LOG_DEBUG, "sleeping %i seconds (\"monitor_interval_secs\")",
config_file_options.monitor_interval_secs);
sleep(config_file_options.monitor_interval_secs);
}
}

2
repmgrd.c
View File

@@ -37,7 +37,6 @@ PGconn *local_conn = NULL;
/* Collate command line errors here for friendlier reporting */
static ItemList cli_errors = { NULL, NULL };
int server_version_num = 0;
bool startup_event_logged = false;
MonitoringState monitoring_state = MS_NORMAL;
@@ -57,7 +56,6 @@ static void show_usage(void);
static void daemonize_process(void);
static void check_and_create_pid_file(const char *pid_file);
static void start_monitoring(void);

1
repmgrd.h
View File

@@ -27,7 +27,6 @@ extern t_configuration_options config_file_options;
extern t_node_info local_node_info;
extern PGconn *local_conn;
extern bool startup_event_logged;
extern int server_version_num;
PGconn *try_reconnect(const char *conninfo, NodeStatus *node_status);