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doc: improve BDR failover documentation

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Ian Barwick
2018-02-05 13:25:49 +09:00
parent c19e7f1025
commit 3b823396eb
1 changed files with 33 additions and 20 deletions
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doc/repmgrd-bdr.sgml
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@@ -174,17 +174,13 @@
<para> <para>
Key to "failover" execution is the <literal>event_notification_command</literal>, Key to "failover" execution is the <literal>event_notification_command</literal>,
which is a user-definable script specified in <filename>repmpgr.conf</filename> which is a user-definable script specified in <filename>repmpgr.conf</filename>
and which should reconfigure the proxy server/ connection pooler to point and which can use a &repmgr; <link linkend="event-notifications">event notification</link>
to the other, still-active node. to reconfigure the proxy server / connection pooler so it points to the other, still-active node.
Details of the event will be passed as parameters to the script.
</para> </para>
<para> <para>
Each time &repmgr; (or <application>repmgrd</application>) records an event, Following parameter placeholders are available for the script definition in <filename>repmpgr.conf</filename>;
it can optionally execute the script defined in these will be replaced with the appropriate value when the script is executed:
<literal>event_notification_command</literal> to take further action;
details of the event will be passed as parameters.
</para>
<para>
Following placeholders are available to the script:
</para> </para>
<variablelist> <variablelist>
@@ -231,20 +227,35 @@
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry>
<term><option>%c</option></term>
<listitem>
<para>
conninfo string of the next available node (<varname>bdr_failover</varname>)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>%a</option></term>
<listitem>
<para>
name of the next available node (<varname>bdr_failover</varname>)
</para>
</listitem>
</varlistentry>
</variablelist> </variablelist>
<para> <para>
Note that <literal>%c</literal> and <literal>%a</literal> will only be provided during Note that <literal>%c</literal> and <literal>%a</literal> are only provided with
<varname>bdr_failover</varname> events, which is what is of interest here. particular failover events, in this case <varname>bdr_failover</varname>.
</para> </para>
<para> <para>
The provided sample script (`scripts/bdr-pgbouncer.sh`) is configured like The provided sample script (`scripts/bdr-pgbouncer.sh`) is configured as follows:
this:
<programlisting> <programlisting>
event_notification_command='/path/to/bdr-pgbouncer.sh %n %e %s "%c" "%a"'</programlisting> event_notification_command='/path/to/bdr-pgbouncer.sh %n %e %s "%c" "%a"'</programlisting>
</para> </para>
<para> <para>
and parses the configures parameters like this: and parses the placeholder parameters like this:
<programlisting> <programlisting>
NODE_ID=$1 NODE_ID=$1
EVENT_TYPE=$2 EVENT_TYPE=$2
@@ -252,12 +263,14 @@
NEXT_CONNINFO=$4 NEXT_CONNINFO=$4
NEXT_NODE_NAME=$5</programlisting> NEXT_NODE_NAME=$5</programlisting>
</para> </para>
<note>
<para> <para>
The script also contains some hard-coded values about the <application>PgBouncer</application> The sample script also contains some hard-coded values for the <application>PgBouncer</application>
configuration for both nodes; these will need to be adjusted for your local environment configuration for both nodes; these will need to be adjusted for your local environment
(ideally the scripts would be maintained as templates and generated by some (ideally the scripts would be maintained as templates and generated by some
kind of provisioning system). kind of provisioning system).
</para> </para>
</note>
<para> <para>
The script performs following steps: The script performs following steps: