Add "repmgr bdr register"

README.md

@@ -37,6 +37,8 @@ Currently available:
     repmgr standby promote
     repmgr standby follow
 
+    repmgr bdr register
+
     repmgr cluster event [--all] [--node-id] [--node-name] [--event] [--event-matching]
 
 
@@ -63,3 +65,67 @@ and vice-versa, e.g. to avoid hard-coding things like a node's
 upstream ID which might change.
 
 TODO: possibly add a config file conversion script/function.
+
+Generating event notifications with repmgr/repmgrd
+--------------------------------------------------
+
+Each time `repmgr` or `repmgrd` perform a significant event, a record
+of that event is written into the `repl_events` table together with
+a timestamp, an indication of failure or success, and further details
+if appropriate. This is useful for gaining an overview of events
+affecting the replication cluster. However note that this table has
+advisory character and should be used in combination with the `repmgr`
+and PostgreSQL logs to obtain details of any events.
+
+Example output after a master was registered and a standby cloned
+and registered:
+
+    repmgr=# SELECT * from repmgr_test.repl_events ;
+     node_id |      event       | successful |        event_timestamp        |                                       details
+    ---------+------------------+------------+-------------------------------+-------------------------------------------------------------------------------------
+           1 | master_register  | t          | 2016-01-08 15:04:39.781733+09 |
+           2 | standby_clone    | t          | 2016-01-08 15:04:49.530001+09 | Cloned from host 'repmgr_node1', port 5432; backup method: pg_basebackup; --force: N
+           2 | standby_register | t          | 2016-01-08 15:04:50.621292+09 |
+    (3 rows)
+
+Additionally, event notifications can be passed to a user-defined program
+or script which can take further action, e.g. send email notifications.
+This is done by setting the `event_notification_command` parameter in
+`repmgr.conf`.
+
+This parameter accepts the following format placeholders:
+
+    %n - node ID
+    %e - event type
+    %s - success (1 or 0)
+    %t - timestamp
+    %d - details
+
+The values provided for "%t" and "%d" will probably contain spaces,
+so should be quoted in the provided command configuration, e.g.:
+
+    event_notification_command='/path/to/some/script %n %e %s "%t" "%d"'
+
+Additionally the following format placeholders are available for the even
+type `bdr_failover`:
+
+    %c - conninfo string of the next available node
+    %a - name of the next available node
+
+These should always be quoted.
+
+By default, all notification type will be passed to the designated script;
+the notification types can be filtered to explicitly named ones:
+
+    event_notifications=master_register,standby_register
+
+The following event types are available:
+
+  ...
+  * `bdr_failover`
+  * `bdr_register`
+  * `bdr_unregister`
+
+Note that under some circumstances (e.g. no replication cluster master could
+be located), it will not be possible to write an entry into the `repl_events`
+table, in which case `event_notification_command` can serve as a fallback.