Configure proxy settings for machined

The machined pull does not utilize the lxc_cache_environment
variable to configure its environment, so it will not use proxies.

This fixes machined to properly configure its environment so pulls
can operate through proxies.

Based on https://wbl.krm.io/howto-proxify-systemd-machined/

Change-Id: I17c452a8ba67561435737ee9d672219a2e306489

tasks/lxc_cache_preparation.yml

@@ -35,6 +35,30 @@
       {%- endfor %}
       {{- images -}}
 
+- block:
+    - name: Create machined proxy override unit directories
+      file:
+        path: "/etc/systemd/system/{{ item }}"
+        owner: root
+        group: root
+        mode: '0755'
+        state: directory
+      with_items:
+        - systemd-machined.service.d
+        - systemd-importd.service.d
+
+    - name: Drop the machined proxy override units
+      template:
+        src: systemd-proxy-unit.conf.j2
+        dest: /etc/systemd/system/{{ item }}/proxy.conf
+        owner: root
+        group: root
+        mode: '0644'
+      with_items:
+        - systemd-machined.service.d
+        - systemd-importd.service.d
+  when: lxc_cache_environment.keys() | length > 0
+
 - include: "lxc_cache_preparation_systemd_{{ (systemd_version.stdout_lines[0].split()[-1] | int > 219) | ternary('new', 'old') }}.yml"
 
 - name: Generate apt keys from LXC host for the container cache

tasks/lxc_cache_preparation_systemd_new.yml

@@ -15,7 +15,7 @@
 
 # NOTE(cloudnull): When modern SystemD is running everywhere this can be
 #  collapsed back into the base preparation task file.
-- name : Remove old image cache
+- name: Remove old image cache
   command: "machinectl remove {{ lxc_container_base_name }}"
   register: cache_refresh
   changed_when: cache_refresh.rc == 0

templates/systemd-proxy-unit.conf.j2

@@ -0,0 +1,6 @@
+# {{ ansible_managed }}
+
+[Service]
+{% for key, value in lxc_cache_environment.iteritems() %}
+Environment={{ key }}={{ value }}
+{% endfor %}