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repmgr/doc/repmgr-cluster-show.xml
2020-02-26 16:02:08 +09:00

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<refentry id="repmgr-cluster-show">
<indexterm>
<primary>repmgr cluster show</primary>
</indexterm>
<refmeta>
<refentrytitle>repmgr cluster show</refentrytitle>
</refmeta>
<refnamediv>
<refname>repmgr cluster show</refname>
<refpurpose>display information about each registered node in the replication cluster</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
<para>
Displays information about each registered node in the replication cluster. This
command polls each registered server and shows its role (<literal>primary</literal> /
<literal>standby</literal>) and status. It polls each server
directly and can be run on any node in the cluster; this is also useful when analyzing
connectivity from a particular node.
</para>
<para>
For PostgreSQL 9.6 and later, the output will also contain the node's current timeline ID.
</para>
<para>
Node availability is tested by connecting from the node where
<command>repmgr cluster show</command> is executed, and does not necessarily imply the node
is down. See <xref linkend="repmgr-cluster-matrix"/> and <xref linkend="repmgr-cluster-crosscheck"/> to get
better overviews of connections between nodes.
</para>
</refsect1>
<refsect1>
<title>Execution</title>
<para>
This command requires either a valid <filename>repmgr.conf</filename> file or a database
connection string to one of the registered nodes; no additional arguments are needed.
</para>
<para>
To show database connection errors when polling nodes, run the command in
<literal>--verbose</literal> mode.
</para>
</refsect1>
<refsect1>
<title>Example</title>
<para>
<programlisting>
$ repmgr -f /etc/repmgr.conf cluster show
ID | Name | Role | Status | Upstream | Location | Priority | Timeline | Connection string
----+-------+---------+-----------+----------+----------+----------+----------+-----------------------------------------
1 | node1 | primary | * running | | default | 100 | 1 | host=db_node1 dbname=repmgr user=repmgr
2 | node2 | standby | running | node1 | default | 100 | 1 | host=db_node2 dbname=repmgr user=repmgr
3 | node3 | standby | running | node1 | default | 100 | 1 | host=db_node3 dbname=repmgr user=repmgr
4 | node4 | standby | running | node1 | default | 100 | 1 | host=db_node4 dbname=repmgr user=repmgr
5 | node5 | witness | * running | node1 | default | 0 | n/a | host=db_node5 dbname=repmgr user=repmgr</programlisting>
</para>
</refsect1>
<refsect1>
<title>Notes</title>
<para>
The column <literal>Role</literal> shows the expected server role according to the
&repmgr; metadata.
</para>
<para>
<literal>Status</literal> shows whether the server is running or unreachable.
If the node has an unexpected role not reflected in the &repmgr; metadata, e.g. a node was manually
promoted to primary, this will be highlighted with an exclamation mark.
If a connection to the node cannot be made, this will be highlighted with a question mark.
Note that the node will only be shown as <literal>? unreachable</literal>
if a connection is not possible at network level; if the PostgreSQL instance on the
node is pingable but not accepting connections, it will be shown as <literal>? running</literal>.
</para>
<para>
In the following example, executed on <literal>node3</literal>, <literal>node1</literal> is not reachable
at network level and assumed to be down; <literal>node2</literal> has been promoted to primary
(but <literal>node3</literal> is not attached to it, and its metadata has not yet been updated);
<literal>node4</literal> is running but rejecting connections (from <literal>node3</literal> at least).
<programlisting>
ID | Name | Role | Status | Upstream | Location | Priority | Timeline | Connection string
----+-------+---------+----------------------+----------+----------+----------+----------+----------------------------------------------------
1 | node1 | primary | ? unreachable | | default | 100 | | host=db_node1 dbname=repmgr user=repmgr
2 | node2 | standby | ! running as primary | ? node1 | default | 100 | 2 | host=db_node2 dbname=repmgr user=repmgr
3 | node3 | standby | running | ? node1 | default | 100 | 1 | host=db_node3 dbname=repmgr user=repmgr
4 | node4 | standby | ? running | ? node1 | default | 100 | | host=db_node4 dbname=repmgr user=repmgr
WARNING: following issues were detected
- unable to connect to node "node1" (ID: 1)
- node "node1" (ID: 1) is registered as an active primary but is unreachable
- node "node2" (ID: 2) is registered as standby but running as primary
- unable to connect to node "node2" (ID: 2)'s upstream node "node1" (ID: 1)
- unable to determine if node "node2" (ID: 2) is attached to its upstream node "node1" (ID: 1)
- unable to connect to node "node3" (ID: 3)'s upstream node "node1" (ID: 1)
- unable to determine if node "node3" (ID: 3) is attached to its upstream node "node1" (ID: 1)
- unable to connect to node "node4" (ID: 4)
HINT: execute with --verbose option to see connection error messages</programlisting>
</para>
<para>
To diagnose connection issues, execute <command>repmgr cluster show</command>
with the <option>--verbose</option> option; this will display the error message
for each failed connection attempt.
</para>
<tip>
<para>
Use <xref linkend="repmgr-cluster-matrix"/> and <xref linkend="repmgr-cluster-crosscheck"/>
to diagnose connection issues across the whole replication cluster.
</para>
</tip>
</refsect1>
<refsect1>
<title>Options</title>
<variablelist>
<varlistentry>
<term><option>--csv</option></term>
<listitem>
<para>
<command>repmgr cluster show</command> accepts an optional parameter <literal>--csv</literal>, which
outputs the replication cluster's status in a simple CSV format, suitable for
parsing by scripts, e.g.:
<programlisting>
$ repmgr -f /etc/repmgr.conf cluster show --csv
1,-1,-1
2,0,0
3,0,1</programlisting>
</para>
<para>
The columns have following meanings:
<itemizedlist spacing="compact" mark="bullet">
<listitem>
<simpara>
node ID
</simpara>
</listitem>
<listitem>
<simpara>
availability (0 = available, -1 = unavailable)
</simpara>
</listitem>
<listitem>
<simpara>
recovery state (0 = not in recovery, 1 = in recovery, -1 = unknown)
</simpara>
</listitem>
</itemizedlist>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--compact</option></term>
<listitem>
<para>
Suppress display of the <literal>conninfo</literal> column.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--terse</option></term>
<listitem>
<para>
Suppress warnings about connection issues.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--verbose</option></term>
<listitem>
<para>
Display the full text of any database connection error messages
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Exit codes</title>
<para>
One of the following exit codes will be emitted by <command>repmgr cluster show</command>:
</para>
<variablelist>
<varlistentry>
<term><option>SUCCESS (0)</option></term>
<listitem>
<para>
No issues were detected.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>ERR_BAD_CONFIG (1)</option></term>
<listitem>
<para>
An issue was encountered while attempting to retrieve
&repmgr; metadata.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>ERR_DB_CONN (6)</option></term>
<listitem>
<para>
&repmgr; was unable to connect to the local PostgreSQL instance.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>ERR_NODE_STATUS (25)</option></term>
<listitem>
<para>
One or more issues were detected with the replication configuration,
e.g. a node was not in its expected state.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>See also</title>
<para>
<xref linkend="repmgr-node-status"/>, <xref linkend="repmgr-node-check"/>, <xref linkend="repmgr-service-status"/>
</para>
</refsect1>
</refentry>