repmgr/doc/repmgr-node-check.xml

<refentry id="repmgr-node-check">
  <indexterm>
    <primary>repmgr node check</primary>
  </indexterm>

  <refmeta>
    <refentrytitle>repmgr node check</refentrytitle>
  </refmeta>

  <refnamediv>
    <refname>repmgr node check</refname>
    <refpurpose>performs some health checks on a node from a replication perspective</refpurpose>
  </refnamediv>

  <refsect1>
    <title>Description</title>
    <para>
      Performs some health checks on a node from a replication perspective.
      This command must be run on the local node.
    </para>
	<note>
	  <para>
		Currently &repmgr; performs health checks on physical replication
		slots only, with the aim of warning about streaming replication standbys which
		have become detached and the associated risk of uncontrolled WAL file
		growth.
	  </para>
	</note>
  </refsect1>

  <refsect1>
    <title>Example</title>
    <para>
      <programlisting>
       $ repmgr -f /etc/repmgr.conf node check
       Node "node1":
            Server role: OK (node is primary)
            Replication lag: OK (N/A - node is primary)
            WAL archiving: OK (0 pending files)
            Downstream servers: OK (2 of 2 downstream nodes attached)
            Replication slots: OK (node has no physical replication slots)
            Missing replication slots: OK (node has no missing physical replication slots)</programlisting>
    </para>
  </refsect1>
  <refsect1>
    <title>Individual checks</title>
    <para>
      Each check can be performed individually by supplying
      an additional command line parameter, e.g.:
      <programlisting>
        $ repmgr node check --role
        OK (node is primary)</programlisting>
    </para>
    <para>
	  Parameters for individual checks are as follows:
    <itemizedlist spacing="compact" mark="bullet">

     <listitem>
      <simpara>
        <literal>--role</literal>: checks if the node has the expected role
      </simpara>
     </listitem>

     <listitem>
      <simpara>
        <literal>--replication-lag</literal>: checks if the node is lagging by more than
        <varname>replication_lag_warning</varname> or <varname>replication_lag_critical</varname>
      </simpara>
     </listitem>

     <listitem>
      <simpara>
        <literal>--archive-ready</literal>: checks for WAL files which have not yet been archived,
        and returns <literal>WARNING</literal> or <literal>CRITICAL</literal> if the number
        exceeds <varname>archive_ready_warning</varname> or <varname>archive_ready_critical</varname> respectively.
      </simpara>
     </listitem>

     <listitem>
      <simpara>
        <literal>--downstream</literal>: checks that the expected downstream nodes are attached
      </simpara>
     </listitem>

     <listitem>
      <simpara>
        <literal>--slots</literal>: checks there are no inactive physical replication slots
      </simpara>
     </listitem>

     <listitem>
      <simpara>
        <literal>--missing-slots</literal>: checks there are no missing physical replication slots
      </simpara>
     </listitem>

     <listitem>
      <simpara>
        <literal>--data-directory-config</literal>: checks the data directory configured in
        <filename>repmgr.conf</filename> matches the actual data directory.
        This check is not directly related to replication, but is useful to verify &repmgr;
        is correctly configured.
      </simpara>
     </listitem>


    </itemizedlist>
  </para>
  </refsect1>

  <refsect1>
    <title>Output format</title>
    <para>
      <itemizedlist spacing="compact" mark="bullet">

        <listitem>
          <simpara>
            <literal>--csv</literal>: generate output in CSV format (not available
            for individual checks)
          </simpara>
        </listitem>

        <listitem>
          <simpara>
            <literal>--nagios</literal>: generate output in a Nagios-compatible format
            (for individual checks only)
          </simpara>
        </listitem>
      </itemizedlist>
    </para>
  </refsect1>

  <refsect1>
    <title>Exit codes</title>

    <para>
      When executing <command>repmgr node check</command> with one of the individual
      checks listed above, &repmgr; will emit one of the following Nagios-style exit codes
      (even if <literal>--nagios</literal> is not supplied):

      <itemizedlist spacing="compact" mark="bullet">

        <listitem>
          <simpara>
            <literal>0</literal>: OK
          </simpara>
        </listitem>

        <listitem>
          <simpara>
            <literal>1</literal>: WARNING
          </simpara>
        </listitem>

        <listitem>
          <simpara>
            <literal>2</literal>: ERROR
          </simpara>
        </listitem>

        <listitem>
          <simpara>
            <literal>3</literal>: UNKNOWN
          </simpara>
        </listitem>

      </itemizedlist>
    </para>



    <para>
      One of the following exit codes will be emitted by <command>repmgr status check</command>
      if no individual check was specified.
    </para>

    <variablelist>

      <varlistentry>
        <term><option>SUCCESS (0)</option></term>
        <listitem>
          <para>
            No issues were detected.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>ERR_NODE_STATUS (25)</option></term>
        <listitem>
          <para>
            One or more issues were detected.
          </para>
        </listitem>
      </varlistentry>

   </variablelist>

  </refsect1>



  <refsect1>
    <title>See also</title>
    <para>
     <xref linkend="repmgr-node-status"/>, <xref linkend="repmgr-cluster-show"/>
    </para>
  </refsect1>

</refentry>