keepalived: Initial commit

Running `keepalived` as a DaemonSet will allow managing floating
"virtual" IP addresses for Kubernetes services with configured external
IP addresses.  The main services we want to expose outside the cluster
are _ingress-nginx_, Mosquitto, and RabbitMQ.  The `keepalived` cluster
will negotiate using the VRRF protocol to determine which node should
have each external address.  Using the process tracking feature of
`keepalived`, we can steer traffic directly to the node where the target
service is running.

keepalived/keepalived.conf

@@ -0,0 +1,60 @@
+# vim: set sw=4 ts=4 sts=4 et:
+includea /run/keepalived.interface
+
+global_defs {
+    max_auto_priority 79
+}
+
+vrrp_track_process ingress-nginx {
+    process nginx-ingress-c
+    weight 90
+}
+
+vrrp_track_process mosquitto {
+    process mosquitto
+    weight 90
+}
+
+vrrp_track_process rabbitmq {
+    process rabbitmq-server
+    weight 90
+}
+
+vrrp_instance ingress-nginx {
+    state BACKUP
+    priority 100
+    interface ${INTERFACE}
+    virtual_router_id 51
+    virtual_ipaddress {
+        172.30.0.147/28
+    }
+    track_process {
+        ingress-nginx
+    }
+}
+
+vrrp_instance mosquitto {
+    state BACKUP
+    priority 100
+    interface ${INTERFACE}
+    virtual_router_id 52
+    virtual_ipaddress {
+        172.30.0.148/28
+    }
+    track_process {
+        mosquitto
+    }
+}
+
+vrrp_instance rabbitmq {
+    state BACKUP
+    priority 100
+    interface ${INTERFACE}
+    virtual_router_id 53
+    virtual_ipaddress {
+        172.30.0.149/28
+    }
+    track_process {
+        rabbitmq
+    }
+}