-#PgBouncer Slony-I replication set follower
+#PgBouncer Slony-I replication set & WAL replication follower
This script is a command-line utility to monitor the nodes in a Slony-I cluster
and reconfigure pgbouncer to follow an origin or subscriber of replication sets.
+Additionally the script can be used to follow WAL streaming primary/secondary
+databases.
The idea is pretty simple; periodically poll the slony schema to identify origin
and subscriber nodes and repoint an existing pgbouncer instance to follow either
-the origin for read-write or a subscriber for read-only operation. The script
-takes a template pgbouncer.ini file containing all the desired settings except
+the origin for read-write or a subscriber for read-only operation. For binary WAL
+replication we instead periodically poll pg_*() functions on all servers to get a
+picture of replication status (pg_is_in_recovery(),pg_last_xlog_receive_location(),
+pg_current_xlog_location() and pg_last_xact_replay_timestamp()).
+
+Side note:
+>Support for binary/WAL replication is an afterthought, so binary replicas are
+>considered followers of the primary if they're on the same timeline. In future
+>it should be possible to improve this for replicas using replication slots
+>and pull all information required from the primary by looking at pg_replication_slots/
+>pg_stat_replication. It would also hopefully be possible to support following
+>logical replication origins similar to how we follow slony origins.
+
+The script takes a template pgbouncer.ini file containing all the desired settings except
for the target database and will write a copy with the target database and reload
-pgbouncer. In 'ro' mode the script will try and choose a subscriber node closest
-to pgbouncer host if IPv4 addressing has been used for the slony conninfos.
+pgbouncer. In 'ro' mode for slony replicas (not WAL replicas currently) the script
+will try and choose a subscriber node closest to pgbouncer host if IPv4 addressing
+has been used for the slony conninfos.
##Example usage
##Configuration options
-| Section | Parameter | Type | Default | Comment
-|:----------|:-----------------------|:--------|:--------------------------------------------|:-----------------------------------
-| Slony | slony_user | text | *'slony'* | Username used to connect to PostgreSQL and select from slony schema tables
-| Slony | slony_pass | text | *''* | Recommended to leave blank and use .pgpass file
-| Slony | slony_cluster_name | text | *'replication'* | Name of slony cluster (without leading underscore of schema name)
-| Slony | server_conninfo | text | *null* | Conninfo string for slony a node, can be specified multiple times
-| pgBouncer | debug | boolean | *false* | Churn out debugging info to log file / stdout
-| pgBouncer | follower_poll_interval | integer | *1000* | Interval to poll slony cluster state when in daemon mode
-| pgBouncer | sets_to_follow | text | *1* | Comma separated list of sets to follow or 'all' to follow all sets
-| pgBouncer | pool_mode | 'ro/rw' | *'rw'* | Select a read-only subscriber or the origin for read-write
-| pgBouncer | pool_all_databases | boolean | *'false'* | If true uses wildcard for database name in pgbouncer.ini, false uses slony database
-| pgBouncer | only_follow_origins | boolean | *'false'* | If true pgbouncer will only be reconfigured and reloaded when sets move origin
-| pgBouncer | status_file | text | *'/tmp/pgbouncer_follower_%mode.status'* | File used to store a hash depicting the state of the cluster
-| pgBouncer | log_file | text | *'/tmp/pgbouncer_follower_%mode.log'* | Log file for the script
-| pgBouncer | pid_file | text | *'/tmp/pgbouncer_follower_%mode.log'* | PID file for the script when run as a daemon
-| pgBouncer | pool_conf_template | text | *'/etc/pgbouncer/pgbouncer_%mode.template'* | Template pgbouncer.ini file with your settings and a blank [databases] section
-| pgBouncer | pool_conf_target | text | *'/etc/pgbouncer/pgbouncer_%mode.ini'* | Target pgbouncer.ini file to write a copy of pool_conf_template with a [databases] section to
-| pgBouncer | pool_reload_command | text | *'/etc/init.d/pgbouncer_%mode reload"'* | System command to execute to reload pgbouncer instance
-| pgBouncer | max_ro_lag | integer | *0* | Maximum lag in seconds allowed for subscriber nodes when running in ro mode. 0 = don't monitor lag.
+| Section | Parameter | Type | Default | Comment
+|:------------|:-----------------------|:--------|:--------------------------------------------|:-----------------------------------
+| Replication | replication_user | text | *'slony'* | Username used to connect to PostgreSQL and select from slony schema tables
+| Replication | replication_pass | text | *''* | Recommended to leave blank and use .pgpass file
+| Replication | replication_method | text | *'slony'* | Specifies replication method in use, possible values 'slony' or 'wal'
+| Slony | slony_cluster_name | text | *'replication'* | Name of slony cluster (without leading underscore of schema name)
+| Server | server_conninfo | text | *null* | Conninfo string for server, can be specified multiple times. For slony only one conninfo is required (but all nodes recommended), for WAL replication all servers required
+| pgBouncer | debug | boolean | *false* | Churn out debugging info to log file / stdout
+| pgBouncer | follower_poll_interval | integer | *1000* | Interval to poll slony cluster state when in daemon mode
+| pgBouncer | sets_to_follow | text | *1* | Comma separated list of sets to follow or 'all' to follow all sets
+| pgBouncer | pool_mode | 'ro/rw' | *'rw'* | Select a read-only subscriber or the origin for read-write
+| pgBouncer | pool_all_databases | boolean | *'false'* | If true uses wildcard for database name in pgbouncer.ini, false uses slony database
+| pgBouncer | auth_user | text | *''* | If set auth_user will be appended to conninfo written in [databases] section
+| pgBouncer | only_follow_origins | boolean | *'false'* | If true pgbouncer will only be reconfigured and reloaded when sets move origin
+| pgBouncer | status_file | text | *'/tmp/pgbouncer_follower_%mode.status'* | File used to store a hash depicting the state of the cluster
+| pgBouncer | log_file | text | *'/tmp/pgbouncer_follower_%mode.log'* | Log file for the script
+| pgBouncer | pid_file | text | *'/tmp/pgbouncer_follower_%mode.log'* | PID file for the script when run as a daemon
+| pgBouncer | pool_conf_template | text | *'/etc/pgbouncer/pgbouncer_%mode.template'* | Template pgbouncer.ini file with your settings and a blank [databases] section
+| pgBouncer | pool_conf_target | text | *'/etc/pgbouncer/pgbouncer_%mode.ini'* | Target pgbouncer.ini file to write a copy of pool_conf_template with a [databases] section to
+| pgBouncer | pool_reload_command | text | *'/etc/init.d/pgbouncer_%mode reload"'* | System command to execute to reload pgbouncer instance
+| pgBouncer | max_ro_lag | integer | *0* | Maximum lag in seconds allowed for subscriber nodes when running in ro mode. 0 = don't monitor lag.
The status_file, log_file, pid_file, pool_conf_template, pool_conf_target and
pool_reload_command parameters can contain the following special values:
projects / slony-i / pgbouncer_follower / blobdiff