r/systemd-resolved: Manage systemd resolver daemon

The *systemd-resolved* role/playbook ensures the *systemd-resolved*
service is enabled and running, and ensures that the `/etc/resolv.conf`
file is a symlink to the appropriate managed configuration file.

roles/systemd-resolved/defaults/main.yml

@@ -0,0 +1,3 @@
+resolved_stub_mode: false
+resolv_conf_symlink: >-
+  /run/systemd/resolve/{% if resolved_stub_mode %}stub-{% endif%}resolv.conf

roles/systemd-resolved/tasks/main.yml

@@ -0,0 +1,20 @@
+- name: ensure systemd-resolved starts at boot
+  service:
+    name: systemd-resolved
+    enabled: true
+  tags:
+  - service
+- name: ensure systemd-resolved is running
+  service:
+    name: systemd-resolved
+    state: started
+  tags:
+  - service
+- name: ensure resolv.conf symlink is set
+  file:
+    path: /etc/resolv.conf
+    src: '{{ resolv_conf_symlink }}'
+    force: true
+    state: link
+  tags:
+  - resolvconf

systemd-resolved.yml

@@ -0,0 +1,6 @@
+- hosts: all
+  roles:
+  - role: systemd-resolved
+    tags:
+    - resolved
+    - netconfig