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doc: document "child_node" events

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Ian Barwick
2019-04-24 13:19:00 +09:00
parent 8d80267ab1
commit 090493ebc9
2 changed files with 147 additions and 10 deletions
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21
doc/event-notifications.sgml
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@@ -91,8 +91,7 @@
may contain spaces, so should be quoted in the provided command may contain spaces, so should be quoted in the provided command
configuration, e.g.: configuration, e.g.:
<programlisting> <programlisting>
event_notification_command='/path/to/some/script %n %e %s "%t" "%d"' event_notification_command='/path/to/some/script %n %e %s "%t" "%d"'</programlisting>
</programlisting>
</para> </para>
<para> <para>
@@ -147,7 +146,10 @@
<para> <para>
By default, all notification types will be passed to the designated script; By default, all notification types will be passed to the designated script;
the notification types can be filtered to explicitly named ones using the the notification types can be filtered to explicitly named ones using the
<varname>event_notifications</varname> parameter. <varname>event_notifications</varname> parameter, e.g.:
<programlisting>
event_notifications=primary_register,standby_register,witness_register</programlisting>
</para> </para>
<para> <para>
@@ -255,6 +257,19 @@
<simpara><literal>standby_recovery</literal></simpara> <simpara><literal>standby_recovery</literal></simpara>
</listitem> </listitem>
<listitem>
<simpara><literal><link linkend="repmgrd-primary-child-disconnection-events">child_node_disconnect</link></literal></simpara>
</listitem>
<listitem>
<simpara><literal><link linkend="repmgrd-primary-child-disconnection-events">child_node_reconnect</link></literal></simpara>
</listitem>
<listitem>
<simpara><literal><link linkend="repmgrd-primary-child-disconnection-events">child_node_new_connect</link></literal></simpara>
</listitem>
<listitem>
<simpara><literal><link linkend="repmgrd-primary-child-disconnection-events">child_nodes_disconnect_command</link></literal></simpara>
</listitem>
</itemizedlist> </itemizedlist>
</para> </para>

136
doc/repmgrd-automatic-failover.sgml
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@@ -165,7 +165,7 @@
</sect1> </sect1>
<sect1 id="repmgrd-primary-standby-disconnection" xreflabel="Monitoring standby disconnections on the primary"> <sect1 id="repmgrd-primary-child-disconnection" xreflabel="Monitoring standby disconnections on the primary">
<indexterm> <indexterm>
<primary>repmgrd</primary> <primary>repmgrd</primary>
<secondary>standby disconnection</secondary> <secondary>standby disconnection</secondary>
@@ -192,13 +192,19 @@
example to &quot;fence&quot; the node and ensure it is isolated from any example to &quot;fence&quot; the node and ensure it is isolated from any
applications attempting to access the replication cluster. applications attempting to access the replication cluster.
</para> </para>
<para>
<sect2 id="repmgrd-primary-child-disconnection-monitoring-process">
<title>Standby disconnections monitoring process and criteria</title>
<para>
<application>repmgrd</application> monitors attach child nodes and decides
whether to invoke the user-defined command based on the following process
and criteria:
<itemizedlist> <itemizedlist>
<listitem> <listitem>
<para> <para>
Every few seconds (defined by the configuration parameter <varname>child_nodes_check_interval</varname> Every few seconds (defined by the configuration parameter <varname>child_nodes_check_interval</varname>;
(a value of <literal>0</literal> disables this altogether), <application>repmgrd</application> queries a value of <literal>0</literal> disables this altogether), <application>repmgrd</application> queries
the <literal>pg_stat_replication</literal> system view and compares the <literal>pg_stat_replication</literal> system view and compares
the nodes present there against the list of nodes registered with &repmgr; which the nodes present there against the list of nodes registered with &repmgr; which
should be attached to the primary. should be attached to the primary.
@@ -233,7 +239,7 @@
If the <varname>child_nodes_disconnect_command</varname> parameter is set in If the <varname>child_nodes_disconnect_command</varname> parameter is set in
<filename>repmgr.conf</filename>, <application>repmgrd</application> will then loop through all child nodes. <filename>repmgr.conf</filename>, <application>repmgrd</application> will then loop through all child nodes.
If it determines that insufficient child nodes are connected, and a If it determines that insufficient child nodes are connected, and a
minimum of <varname>child_nodes_disconnect_timeout</varname> seconds (default: <literal>30</literal> minimum of <varname>child_nodes_disconnect_timeout</varname> seconds (default: <literal>30</literal>)
has elapsed since the last node became disconnected, <application>repmgrd</application> will then execute the has elapsed since the last node became disconnected, <application>repmgrd</application> will then execute the
<varname>child_nodes_disconnect_command</varname> script. <varname>child_nodes_disconnect_command</varname> script.
</para> </para>
@@ -253,7 +259,8 @@
the criteria for its execution are met again. the criteria for its execution are met again.
</para> </para>
<para> <para>
The <varname>child_nodes_disconnect_command</varname> script will not be executed if <application>repmgrd</application> is paused. The <varname>child_nodes_disconnect_command</varname> script will not be executed if
<application>repmgrd</application> is paused.
</para> </para>
</listitem> </listitem>
@@ -266,7 +273,122 @@
</listitem> </listitem>
</itemizedlist> </itemizedlist>
</para> </para>
</sect2>
<sect2 id="repmgrd-primary-child-disconnection-example">
<title>Standby disconnections monitoring process example</title>
<para>
</para>
</sect2>
<sect2 id="repmgrd-primary-child-disconnection-configuration">
<title>Standby disconnections monitoring process configuration</title>
<para>
</para>
</sect2>
<sect2 id="repmgrd-primary-child-disconnection-events">
<title>Standby disconnections monitoring process event notifications</title>
<para>
The following <link linkend="event-notifications">event notifications</link> may be generated:
</para>
<variablelist>
<varlistentry>
<indexterm>
<primary>child_node_disconnect</primary>
<secondary>event notification</secondary>
</indexterm>
<term><varname>child_node_disconnect</varname></term>
<listitem>
<para>
This event is generated after <application>repmgrd</application>
detects that a child node is no longer streaming from the primary node.
</para>
<para>
Example:
<programlisting>
$ repmgr cluster event --event=child_node_disconnect
Node ID | Name | Event | OK | Timestamp | Details
---------+-------+-----------------------+----+---------------------+--------------------------------------------
1 | node1 | child_node_disconnect | t | 2019-04-24 12:41:36 | node "node3" (node ID: 3) has disconnected</programlisting>
</para>
</listitem>
</varlistentry>
<varlistentry>
<indexterm>
<primary>child_node_reconnect</primary>
<secondary>event notification</secondary>
</indexterm>
<term><varname>child_node_reconnect</varname></term>
<listitem>
<para>
This event is generated after <application>repmgrd</application>
detects that a child node has resumed streaming from the primary node.
</para>
<para>
Example:
<programlisting>
$ repmgr cluster event --event=child_node_reconnect
Node ID | Name | Event | OK | Timestamp | Details
---------+-------+----------------------+----+---------------------+------------------------------------------------------------
1 | node1 | child_node_reconnect | t | 2019-04-24 12:42:19 | node "node3" (node ID: 3) has reconnected after 42 seconds</programlisting>
</para>
</listitem>
</varlistentry>
<varlistentry>
<indexterm>
<primary>child_node_new_connect</primary>
<secondary>event notification</secondary>
</indexterm>
<term><varname>child_node_new_connect</varname></term>
<listitem>
<para>
This event is generated after <application>repmgrd</application>
detects that a new child node has been registered with &repmgr; and has
connected to the primary.
</para>
<para>
Example:
<programlisting>
$ repmgr cluster event --event=child_node_new_connect
Node ID | Name | Event | OK | Timestamp | Details
---------+-------+------------------------+----+---------------------+---------------------------------------------
1 | node1 | child_node_new_connect | t | 2019-04-24 12:41:30 | new node "node3" (node ID: 3) has connected</programlisting>
</para>
</listitem>
</varlistentry>
<varlistentry>
<indexterm>
<primary>child_nodes_disconnect_command</primary>
<secondary>event notification</secondary>
</indexterm>
<term><varname>child_nodes_disconnect_command</varname></term>
<listitem>
<para>
This event is generated after <application>repmgrd</application> detects
that sufficient child nodes have been disconnected for a sufficient amount
of time to trigger execution of the <varname>child_nodes_disconnect_command</varname>.
</para>
<para>
Example:
<programlisting>
$ repmgr cluster event --event=child_nodes_disconnect_command
Node ID | Name | Event | OK | Timestamp | Details
---------+-------+--------------------------------+----+---------------------+--------------------------------------------------------
1 | node1 | child_nodes_disconnect_command | t | 2019-04-24 13:08:17 | "child_nodes_disconnect_command" successfully executed</programlisting>
</para>
</listitem>
</varlistentry>
</variablelist>
</sect2>
</sect1> </sect1>