kea/doc/guide/config.xml

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  <chapter id="kea-config">
    <title>Kea configuration</title>

    <para>Depending on configuration backend chosen  (see <xref
    linkend="dhcp-config-backend"/>), configuration mechanisms are
    different. The following sections describe details of specific configuration
    backends. Note that only one configuration backend can be used and its
    selection is determined during compilation time.</para>

    <section id="bundy-backend">
      <title>Bundy configuration backend</title>
      <para>This legacy configuration backend allows Kea to use former BIND10
      framework. That framework and this Kea configuration backend is no longer
      supported by ISC. It is currently developed as part of Bundy project (see
      <ulink url="http://bundy-dns.de">Bundy homepage</ulink>). See Bundy
      project documentation regarding configuration.</para>
    </section>

    <section id="json-backend">
      <title>JSON configuration backend</title>
      <para>JSON is the default configuration backend and the only one supported
      as of 0.9 release. It assumes that the servers are started from command
      line (either directly or using a script, see TODO for details). JSON
      backend uses certain signals to influence certain behaviors. The
      configuration file is specified upon startup using -c parameter.</para>

      <section id="json-format">
	<title>JSON syntax</title>
	<para>Configuration files for DHCPv4, DHCPv6 and DDNS modules are
	defined in extended JSON format. The basic JSON is defined in <ulink
	url="http://tools.ietf.org/html/rfc4627">RFC 4627</ulink>.  Kea
	components use extended JSON, which extends basic format by allowing
	bash-style comments in the file. Comment lines must have hash (#) in the
	first column.</para>

	<para>Configuration file consists of a single object (often colloquially
	called a map) started with a curly bracket. It consists "Dhcp4",
	"Dhcp6", "DhcpDdns" and/or "Logging" objects. It is possible to define
	additional elements, but they will be ignored. That principle was chosen
	to ease configuration management. For example, it is possible to define
	Dhcp4, Dhcp6 and Logging elements in one configuration file that can be
	used to start both DHCPv4 and DHCPv6 components.  When starting, DHCPv4
	component will use Dhcp4 object to configure itself and Logging to
	configure logging parameters, while ignoring Dhcp6 object.</para>

	<para>For example, a very simple configuration for Dhcp6 could look
	like this:
<screen>
{

# DHCPv6 specific configuration starts here.
"Dhcp6": {

# These are DHCPv6-specific parameters. They will be explained in later sections.
    "interfaces": [ "eth0" ],

    "preferred-lifetime": 3000,
    "valid-lifetime": 4000,
    "renew-timer": 1000,
    "rebind-timer": 2000,

# The following list defines subnets. Each subnet consists of at
# least subnet and pool entries.
    "subnet6": [{
    "pool": [ "2001:db8:1::/80" ],
       "subnet": "2001:db8:1::/64"
    }]
},
# DHCPv6 specific configuration ends here.

# Logger parameters (that could be shared among several components) start here.
"Logging": {

# These are Logger-specific parameters. They will be explained in later sections.
   "loggers": [{
        "name": "*",
        "severity": "DEBUG"
    }]
}
# Logger parameters end here.

}
</screen>
	</para>

        <para>
          More examples are available in the Kea source code in the
          <filename>doc/examples</filename> directory.
        </para>
	
      </section>

      
      <!-- @todo Add a reference here after #3422 is done -->
    </section>


  </chapter>