r/k8s-controller: Deploy HAProxy

The _haproxy_ role only installs HAProxy and provides some basic global
configuration; it expects another role to depend on it and provide
concrete proxy configuration with drop-in configuration files.  Thus, we
need a role specifically for the Kubernetes control plane nodes to
provide the configuration to proxy for the API server.

group_vars/k8s-controller.yml

@@ -21,3 +21,12 @@ vrrp_instance:
     track_process {
         kube-apiserver
     }
+
+kube_root_ca_pem: >-
+  {{ lookup(
+    "kubernetes.core.k8s",
+    kind="ConfigMap",
+    namespace="kube-public",
+    resource_name="kube-root-ca.crt"
+    ).data["ca.crt"]
+  }}