alpine: set hostname

And configure /etc/hosts accordingly.

roles/alpine/tasks/main.yml

@@ -1,3 +1,12 @@
+- name: Set hostname
+  hostname:
+    name: '{{ dns_name }}'
+
+- name: Configure hosts
+  template:
+    dest: /etc/hosts
+    src: hosts.j2
+
 - name: Enable community package repo
   lineinfile:
     path: /etc/apk/repositories