salt: use all etcd servers as apiserver backends

Define all clients URLs as etcd servers for API
server backend, this way, if the local etcd is
down, the API server is still able to answer.

Refs: #2080

salt/metalk8s/kubernetes/apiserver/installed.sls

@@ -21,6 +21,16 @@ Set up default basic auth htpasswd:
     - replace: False
 
 {%- set host = grains['metalk8s']['control_plane_ip'] %}
+{%- set etcd_servers = [] %}
+{%- if 'etcd' in pillar.metalk8s.nodes[grains.id].roles %}
+{%-   do etcd_servers.append("https://" ~ host ~ ":2379") %}
+{%- endif %}
+
+{%- for member in pillar.metalk8s.etcd.members | default([]) %}
+{%-   do etcd_servers.append(member['client_urls']) %}
+{%- endfor %}
+
+{%- set etcd_servers = (etcd_servers | sort) | unique %}
 
 Create kube-apiserver Pod manifest:
   metalk8s.static_pod_managed:
@@ -61,7 +71,7 @@ Create kube-apiserver Pod manifest:
           - --etcd-cafile=/etc/kubernetes/pki/etcd/ca.crt
           - --etcd-certfile=/etc/kubernetes/pki/apiserver-etcd-client.crt
           - --etcd-keyfile=/etc/kubernetes/pki/apiserver-etcd-client.key
-          - --etcd-servers=https://{{ grains.metalk8s.control_plane_ip }}:2379
+          - --etcd-servers={{ etcd_servers | join(",") }}
           - --insecure-port=0
           - --kubelet-client-certificate=/etc/kubernetes/pki/apiserver-kubelet-client.crt
           - --kubelet-client-key=/etc/kubernetes/pki/apiserver-kubelet-client.key