feat: uniform system.content source schema across installers and repositories

roles/bootstrap/tasks/archlinux.yml

@@ -1,9 +1,4 @@
 ---
-- name: Refresh Arch keyring in the live environment
-  ansible.builtin.command: pacman -Sy --noconfirm archlinux-keyring
-  register: bootstrap_arch_keyring
-  changed_when: bootstrap_arch_keyring.rc == 0
-
 - name: Bootstrap ArchLinux
   vars:
     _config: "{{ lookup('vars', bootstrap_var_key) }}"
@@ -13,7 +8,44 @@
         | reject('equalto', '')
         | list
       }}
-  ansible.builtin.command: >-
-    pacstrap /mnt {{ bootstrap_archlinux_packages | join(' ') }}
-  register: bootstrap_result
-  changed_when: bootstrap_result.rc == 0
+  block:
+    - name: Notify that mirror mode falls back to the public mirrorlist
+      when:
+        - system_cfg.content.source == 'mirror'
+        - system_cfg.content.url | length == 0
+      ansible.builtin.debug:
+        msg: >-
+          content.source is 'mirror' but content.url is empty: keeping the live
+          ISO public mirrorlist (refreshed by reflector). Set content.url to pin
+          a specific mirror.
+
+    - name: Point pacman at the content mirror
+      when: system_cfg.content.url | length > 0
+      ansible.builtin.copy:
+        dest: /etc/pacman.d/mirrorlist
+        content: "Server = {{ system_cfg.content.url }}/$repo/os/$arch\n"
+        mode: "0644"
+
+    - name: Refresh Arch keyring in the live environment
+      ansible.builtin.command: pacman -Sy --noconfirm archlinux-keyring
+      environment:
+        http_proxy: "{{ system_cfg.content.proxy }}"
+        https_proxy: "{{ system_cfg.content.proxy }}"
+      register: bootstrap_arch_keyring
+      changed_when: bootstrap_arch_keyring.rc == 0
+
+    - name: Install Arch base system
+      ansible.builtin.command: >-
+        pacstrap /mnt {{ bootstrap_archlinux_packages | join(' ') }}
+      environment:
+        http_proxy: "{{ system_cfg.content.proxy }}"
+        https_proxy: "{{ system_cfg.content.proxy }}"
+      register: bootstrap_result
+      changed_when: bootstrap_result.rc == 0
+
+    - name: Persist the content mirror in the installed system
+      when: system_cfg.content.url | length > 0
+      ansible.builtin.copy:
+        dest: /mnt/etc/pacman.d/mirrorlist
+        content: "Server = {{ system_cfg.content.url }}/$repo/os/$arch\n"
+        mode: "0644"