Configure high-availability

High availability (HA) allows the HAProxy charm to continue to function even if some units fail, while maintaining the same address across all units. This guide walks you through how to configure HA with the help of the hacluster subordinate charm.

Scale the HAProxy charm to three units

Deploy the HAProxy charm with three units since it’s the minimum required by the hacluster charm.

juju deploy haproxy --channel=2.8/edge -n 3

Deploy and integrate the hacluster subordinate charm

Deploy the subordinate charm, and specify --base=ubuntu@24.04 so that the charm is deployed with a base matching the HAProxy charm.

juju deploy hacluster --channel=2.4/edge --base=ubuntu@24.04
juju integrate hacluster haproxy

Configure a virtual IP

A virtual IP is shared between all HAProxy units and serves as the single entrypoint to all requirer applications. To add a virtual IP to the HAProxy charm, use a free IP address from the network of the HAProxy units. This example takes the first available address on the LXD subnet.

VIP="$(echo "${HAPROXY_IP}" | awk -F'.' '{print $1,$2,$3,2}' OFS='.')"
juju config haproxy vip=$VIP

Test our configuration by sending a request to the $VIP. You should see that the request is properly handled by HAProxy.

curl "${VIP}"

If successful, HAProxy will reply with Default page for the haproxy operator..