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  <chapter id="keactrl">
    <title>Managing Kea with keactrl</title>

    <section id="keactrl-overview">
      <title>Overview</title>
      <para>keactrl is a shell script which controls the startup, shutdown
      and reconfiguration of the Kea servers (<command>kea-dhcp4</command>,
      <command>kea-dhcp6</command> and <command>kea-dhcp-ddns</command>). It
      also provides the means for checking the current status of the servers
      and determining the configuration files in use.
      </para>
    </section>

    <section id="keactrl-usage">
      <title>Command Line Options</title>
      <para><command>keactrl</command> is run as follows:
<screen>
keactrl &lt;command&gt; [-c keactrl-config-file] [-s server[,server,..]]
</screen>
      </para>

      <para>
        <command>&lt;command&gt;</command> is the one of the commands
        described in <xref linkend="keactrl-commands"/>.
      </para>

      <para>
        The optional <command>-c keactrl-config-file</command> switch
        allows specification of an alternate <command>keactrl</command>
        configuration file. (<command>--ctrl-config</command> is a synonym for
        <command>-c</command>.) In the absence of <command>-c</command>,
        <command>keactrl</command> will use the default configuration
        file <filename>[kea-install-dir]/etc/kea/keactrl.conf</filename>.
      </para>

      <para>
        The optional <command>-s server[,server ...]</command> switch selects
        the servers to which the command is issued.
        (<command>--server</command> is a synonym for <command>-s</command>.)
        If absent, the command is sent to all servers enabled in the keactrl
        configuration file.
        If multiple servers are specified, they
        should be separated by commas with no intervening spaces.
      </para>
    </section>

    <section id="keactrl-config-file">
      <title>The keactrl Configuration File</title>
      <para>
        Depending on requirements, not all of the available servers need
        be run.  The keactrl configuration file sets which servers are
        enabled and which are disabled.  The default configuration
        file is <filename>[kea-install-dir]/etc/kea/keactrl.conf</filename>,
        but this can be overridden on a per-command basis using the
        <command>-c</command> switch.
      </para>

      <para>
        The contents of <filename>keactrl.conf</filename> are:
<screen>
# This is a configuration file for keactrl script which controls
# the startup, shutdown, reconfiguration and gathering the status
# of the Kea servers.

# prefix holds the location where the Kea is installed.
prefix=/usr/local

# Location of Kea configuration file.
kea_config_file=${prefix}/etc/kea/kea.conf

# Location of Kea binaries.
exec_prefix=${prefix}
dhcp4_srv=${exec_prefix}/sbin/kea/kea-dhcp4
dhcp6_srv=${exec_prefix}/sbin/kea/kea-dhcp6
dhcp_ddns_srv=${exec_prefix}/sbin/kea/kea-dhcp-ddns

# Start DHCPv4 server?
dhcp4=yes

# Start DHCPv6 server?
dhcp6=yes

# Start DHCP DDNS server?
dhcp_ddns=yes

# Be verbose?
kea_verbose=no
</screen>
      </para>

      <para>
        The <parameter>dhcp4</parameter>, <parameter>dhcp6</parameter> and
        <parameter>dhcp_ddns</parameter> parameters set to "yes" configure
        <command>keactrl</command> to manage (start, reconfigure) all servers,
        i.e. <command>kea-dhcp4</command>, <command>kea-dhcp6</command> and
        <command>kea-dhcp-ddns</command>. When any of these parameters is set to
        "no" the <command>keactrl</command> will ignore
        the corresponding server when starting or reconfiguring Kea.
      </para>

      <para>
        By default, Kea servers managed by <command>keactrl</command> are
        located in <filename>[kea-install-dir]/sbin</filename>. This
        should work for most installations. If the default
        location needs to be altered for any reason, the paths
        specified with the <parameter>dhcp4_srv</parameter>,
        <parameter>dhcp6_srv</parameter> and <parameter>dhcp_ddns_srv</parameter>
        parameters should be modified.
      </para>

      <para>
        The <parameter>kea_verbose</parameter> parameter specifies the verbosity
        of the servers being started. When <parameter>kea_verbose</parameter>
        is set to "yes" the logging level of the server is set to DEBUG.
        Modification of the logging severity in a configuration file, as
        described in <xref linkend="logging"/>, will have no effect as long
        as the <parameter>kea_verbose</parameter> is set to "yes". Setting
        it to "no" will cause the server to use the logging levels specified
        in the Kea configuration file for respective loggers. If no
        logging configuration is specified, the default settings will be
        used.
      </para>

      <note>
        <para>
          The verbosity for the server is set  when it is started. Once
          started, the verbosity can be only changed by stopping the server and
          starting it again with the new value of the
          <parameter>kea_verbose</parameter> parameter.
        </para>
      </note>
    </section>

    <section id="keactrl-commands">
      <title>Commands</title>
      <para>The following commands are supported by <command>keactrl</command>:
      <itemizedlist>
        <listitem><simpara>
          <command>start</command> - starts selected servers.
        </simpara></listitem>
        <listitem><simpara>
          <command>stop</command> - stops all running servers.
        </simpara></listitem>
        <listitem><simpara>
          <command>reload</command> - triggers reconfiguration of the
          selected servers by sending the SIGHUP signal to them.
        </simpara></listitem>
        <listitem><simpara>
          <command>status</command> - returns the status of the servers (active
          or inactive) and the names of the configuration files in use.
        </simpara></listitem>
      </itemizedlist>
      </para>

      <para>Typical output from <command>keactrl</command> when starting
      the servers looks similar to the following:
<screen>
<userinput>$ keactrl start</userinput>
INFO/keactrl: Starting kea-dhcp4 -c /usr/local/etc/kea/kea.conf -d
INFO/keactrl: Starting kea-dhcp6 -c /usr/local/etc/kea/kea.conf -d
INFO/keactrl: Starting kea-dhcp-ddns -c /usr/local/etc/kea/kea.conf -d
</screen>
      </para>

      <para>Kea's servers create PID files upon startup. These files are used
      by keactrl to determine whether or not a given server is running.  If
      one or more servers are running when the start command is issued, the
      output will look similar to the following:
<screen>
<userinput>$ keactrl start</userinput>
INFO/keactrl: kea-dhcp4 appears to be running, see: PID 10918, PID file: /usr/local/var/kea/kea.kea-dhcp4.pid.
INFO/keactrl: kea-dhcp6 appears to be running, see: PID 10924, PID file: /usr/local/var/kea/kea.kea-dhcp6.pid.
INFO/keactrl: kea-dhcp-ddns appears to be running, see: PID 10930, PID file: /usr/local/var/kea/kea.kea-dhcp-ddns.pid.
</screen>
      During normal shutdowns these PID files are deleted. They may, however,
      be left over as remnants following a system crash.  It is possible,
      though highly unlikely, that upon system restart the PIDs they contain
      actually refer to processes unrelated to Kea.  This condition will cause
      keactrl to decide that the servers are running, when in fact they are
      not.  In such a case the PID files as listed in the keactrl output
      must be manually deleted.
      </para>

      <para>The following command stops all servers:
<screen>
<userinput>$ keactrl stop</userinput>
INFO/keactrl: Stopping kea-dhcp4...
INFO/keactrl: Stopping kea-dhcp6...
INFO/keactrl: Stopping kea-dhcp-ddns...
</screen>
      Note that the <command>stop</command> will attempt to stop all servers
      regardless of whether they are "enabled" in the <filename>keactrl.conf</filename>.
      If any of the servers are not running, an informational message
      is displayed as in the <command>stop</command> command output below.
<screen>
<userinput>$ keactrl stop</userinput>
INFO/keactrl: kea-dhcp4 isn't running.
INFO/keactrl: kea-dhcp6 isn't running.
INFO/keactrl: kea-dhcp-ddns isn't running.
</screen>
      </para>

      <para>
        As already mentioned, the reconfiguration of each Kea server is
        triggered by the SIGHUP signal. The <command>reload</command>
        command sends the SIGHUP signal to the servers that are enabled in
        the <command>keactrl</command> configuration file and are
        currently running. When a server receives the SIGHUP signal it
        re-reads its configuration file and, if the new configuration is
        valid, uses the new configuration. A reload is executed as follows:
<screen>
<userinput>$ keactrl reload</userinput>
INFO/keactrl: Reloading kea-dhcp4...
INFO/keactrl: Reloading kea-dhcp6...
INFO/keactrl: Reloading kea-dhcp-ddns...
</screen>
      If any of the servers are not running, an informational message
      is displayed as in the <command>reload</command> command output below.
<screen>
<userinput>$ keactrl stop</userinput>
INFO/keactrl: kea-dhcp4 isn't running.
INFO/keactrl: kea-dhcp6 isn't running.
INFO/keactrl: kea-dhcp-ddns isn't running.
</screen>
      </para>

      <note>
        <para>
          Currently <command>keactrl</command> does not report configuration
          failures when the server is started or reconfigured. To check if
          the server's configuration succeeded the Kea log must be examined
          for errors. By default, this is written to the syslog file.
        </para>
      </note>

      <para>
        Sometimes it is useful to check which servers are running. The
        <command>status</command> reports this, typical output looking like:
<screen>
<userinput>$ keactrl status</userinput>
DHCPv4 server: active
DHCPv6 server: inactive
DHCP DDNS: active
Kea configuration file: /usr/local/etc/kea/kea.conf
keactrl configuration file: /usr/local/etc/kea/keactrl.conf
</screen>
      </para>
    </section>

    <section id="keactrl-overriding-servers">
      <title>Overriding the Server Selection</title>
      <para>
        The optional <command>-s</command> switch allows
        the selection of the servers to which <command>keactrl</command>
        command is issued.  For example, the following
        instructs <command>keactrl</command> to stop the
        <command>kea-dhcp4</command> and <command>kea-dhcp6</command> servers
        and leave the <command>kea-dhcp-ddns</command> server running:
<screen>
<userinput>$ keactrl stop -s dhcp4,dhcp6</userinput>
</screen>
      </para>

      <para>
        Similarly, the following
        will only start the <command>kea-dhcp4</command> and
        <command>kea-dhcp-ddns</command> servers and not
        <command>kea-dhcp6</command>.
<screen>
<userinput>$ keactrl start -s dhcp4,dhcp_ddns</userinput>
</screen>
      </para>
      <para>
        Note that the behavior of the <command>-s</command> switch
        with the <command>start</command> and <command>reload</command> commands
        is different to its behavior with the <command>stop</command> command.
        On <command>start</command> and <command>reload</command>,
        <command>keactrl</command> will check if the servers given as
        parameters to the <command>-s</command> switch are
        enabled in the <command>keactrl</command> configuration file:
        if not, the server will be ignored.  For <command>stop</command> however,
        this check is not made: the command is applied to all listed servers,
        regardless of whether they have been enabled in the file.
      </para>

      <para>
        The following keywords can be used with the <command>-s</command>
        command line option:
        <itemizedlist>
          <listitem><simpara>
            <command>dhcp4</command> for <command>kea-dhcp4.</command>
          </simpara></listitem>
          <listitem><simpara>
            <command>dhcp6</command> for <command>kea-dhcp6.</command>
          </simpara></listitem>
          <listitem><simpara>
            <command>dhcp_ddns</command> for <command>kea-dhcp-ddns.</command>
          </simpara></listitem>
          <listitem><simpara>
            <command>all</command> for all servers (default).
          </simpara></listitem>
        </itemizedlist>
      </para>
    </section>
  </chapter>
