Commit 729cbe04 authored by Marcin Siodelski's avatar Marcin Siodelski
Browse files

[5478] Added section about sending lease updates setting.

parent b49cd517
......@@ -820,6 +820,72 @@
hot standby and load balancing mode of operation.</para>
</section> <!-- end of ha-hot-standby-config -->
<section xml:id="ha-send-lease-updates">
<title>Controlling Lease Updates</title>
<para>The HA enabled server informs its active partner about allocated
or renewed leases by sending appropriate control commands. The partner
updates the lease information in its own database. This guarantees
consistency of the lease information between the servers and allows for
designating one of the servers to handle the entire DHCP traffic in
case the other server becomes unavailable.</para>
<para>In some cases, though, it is desired to disable lease updates
between the active servers if the exchange of information about the
allocated leases is performed using some other mechanism. Kea supports
various types of databases to be used as a storage for leases, e.g.
MySQL, Postgres, Cassandra. Those databases include builtin solutions
for data replication which are often used by Kea users to provide
redundancy.</para>
<para>The HA hook library supports such scenarios by allowing to
disable lease updates over the control channel, leaving the server
to rely on the database replication mechanism. This is controlled by
the <command>send-lease-updates</command> boolean parameter, which
value defaults to true:
<screen>
{
"Dhcp4": {
...
"hooks-libraries": [
{
"library": "/usr/lib/hooks/libdhcp_lease_cmds.so",
"parameters": { }
},
{
"library": "/usr/lib/hooks/libdhcp_ha.so",
"parameters": {
"high-availability": [ {
"this-server-name": "server1",
"mode": "load-balancing",
"send-lease-updates": false,
"peers": [
{
"name": "server1",
"url": "http://192.168.56.33:8080/",
"role": "primary"
},
{
"name": "server2",
"url": "http://192.168.56.66:8080/",
"role": "secondary"
}
]
} ]
}
}
],
...
}
</screen>
</para>
</section>
<section xml:id="ha-ctrl-agent-config">
<title>Control Agent Configuration</title>
<para>The <xref linkend="kea-ctrl-agent"/> describes in detail the
......
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