feat(supervised_install): add workaround for broken dns

A new variable `supervised_install_resolve_conf_overrides` can be used to configure resolve.conf overrides if the supervisor's default configuration breaks DNS resolution.

ref: home-assistant/supervised-installer#339

roles/supervised_install/README.md

@@ -16,6 +16,17 @@ OS Packages:
 Role Variables
 --------------
 
+Optional variables with example configurations
+
+```yaml
+# Used to create overrides for resolve.conf to fix DNS resolution
+# If not set, then no resolve.conf overrides will be created
+# ref: https://github.com/home-assistant/supervised-installer/issues/339
+supervised_install_resolve_conf_overrides: |
+  DNS=192.168.68.1
+  DNSStubListener=no
+```
+
 Variables used from fact gathering
 
 - ansible_pkg_mgr: Used to validate that apt is available, since it is used by this role to install OS packages

roles/supervised_install/tasks/main.yml

@@ -59,6 +59,30 @@
         regex: 'precedence ::ffff:0:0/96  100'
         line: 'precedence ::ffff:0:0/96  100'
 
+- name: Configure DNS resolution
+  block:
+    - name: Create resolve.conf drop in directory
+      ansible.builtin.file:
+        path: /etc/systemd/resolve.conf.d
+        state: directory
+        mode: 0755
+
+    - name: Create resolve.conf override config
+      ansible.builtin.copy:
+        content: |
+          [Resolve]
+          {{ supervised_install_resolve_conf_overrides }}
+        dest: /etc/systemd/resolve.conf.d/resolve.conf
+        mode: 0644
+      register: resolve_conf_override_result
+
+    - name: Restart systemd-resolved
+      ansible.builtin.service:
+        name: systemd-resolved
+        state: restarted
+      when: resolve_conf_override_result is changed
+  when: supervised_install_resolve_conf_overrides is defined
+
 - name: Get download url for latest os-agent .deb release
   shell: |
     curl -s https://api.github.com/repos/home-assistant/os-agent/releases/latest \