dhcpd: add support for failover

roles/dhcpd/defaults/main.yml

@@ -5,4 +5,11 @@ dhcpd__max_lease_time: 7200
 dhcpd__dns_servers: []
 dhcpd__domain_search: []
 dhcpd__subnets: []
+dhcpd__failover_port: 519
+dhcpd__failover_mclt: 3600
+dhcpd__failover_split: 128
+dhcpd__failover_max_response_delay: 60
+dhcpd__failover_max_unacked_updates: 10
+dhcpd__failover_lb_max_seconds: 3
+dhcpd__omapi_port: 7911
 ...

roles/dhcpd/templates/dhcpd.conf.j2

@@ -7,12 +7,43 @@ ddns-update-style none;
 
 authoritative;
 
+{% if dhcpd__omapi_key | default({}) %}
+omapi-port {{ dhcpd__omapi_port }};
+omapi-key omapi_key;
+
+key omapi_key {
+    algorithm {{ dhcpd__omapi_key.algorithm }};
+    secret {{ dhcpd__omapi_key.secret }};
+}
+{% endif %}
+
+{% if dhcpd__subnets | selectattr("failover", "true") | list %}
+failover peer "peer" {
+{% if dhcpd__failover_primary | default(false) %}
+    primary;
+    mclt {{ dhcpd__failover_mclt }};
+    split {{ dhcpd__failover_split }};
+{% else %}
+    secondary;
+{% endif %}
+    address {{ dhcpd__failover_address }};
+    port {{ dhcpd__failover_port }};
+    peer address {{ dhcpd__failover_peer_address }};
+    peer port {{ dhcpd__failover_peer_port
+                 | default(dhcpd__failover_port) }};
+    max-response-delay {{ dhcpd__failover_max_response_delay }};
+    max-unacked-updates {{ dhcpd__failover_max_unacked_updates }};
+    load balance max seconds {{ dhcpd__failover_lb_max_seconds }};
+}
+{% endif %}
+
 {% if dhcpd__dns_servers | default([]) %}
 option domain-name-servers {{ dhcpd__dns_servers | join(", ") }};
 {% endif %}
 
 {% if dhcpd__domain_search | default([]) %}
-option domain-search {{ dhcpd__domain_search | map("enquote") | join(", ") }};
+option domain-search {{ dhcpd__domain_search
+                        | map("enquote") | join(", ") }};
 {% endif %}
 
 {% for subnet in dhcpd__subnets %}
@@ -20,7 +51,12 @@ subnet {{ subnet.network
           | ansible.utils.ipaddr("network") }}
         netmask {{ subnet.network
 		   | ansible.utils.ipaddr("netmask") }} {
-    range {{ subnet.start }} {{ subnet.end }};
+    pool {
+       range {{ subnet.start }} {{ subnet.end }};
+{% if subnet.failover | default(false) %}
+       failover peer "peer";
+{% endif %}
+    }
 {% if subnet.routers | default([]) %}
     option routers {{ subnet.routers | join(", ") }};
 {% endif %}