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

roles/bootstrap/tasks/ubuntu.yml

@@ -42,7 +42,10 @@
         --keyring=/usr/share/keyrings/ubuntu-archive-keyring.gpg
         --include={{ bootstrap_ubuntu_base_csv }}
         {{ bootstrap_ubuntu_release }} /mnt
-        {{ system_cfg.mirror | default('http://archive.ubuntu.com/ubuntu', true) }}
+        {{ system_cfg.content.url }}
+      environment:
+        http_proxy: "{{ system_cfg.content.proxy }}"
+        https_proxy: "{{ system_cfg.content.proxy }}"
       register: bootstrap_ubuntu_base_result
       changed_when: bootstrap_ubuntu_base_result.rc == 0
 
@@ -59,6 +62,10 @@
           Acquire::Retries "3";
           Acquire::http::Pipeline-Depth "10";
           APT::Install-Recommends "false";
+          {% if system_cfg.content.proxy | length > 0 %}
+          Acquire::http::Proxy "{{ system_cfg.content.proxy }}";
+          Acquire::https::Proxy "{{ system_cfg.content.proxy }}";
+          {% endif %}
         mode: "0644"
 
     - name: Update package lists