Allow a list of files to be copied into the container cache

In order to better make use of OpenStack-CI's resources (apt mirrors, etc)
we need to be able to copy configuration files which have been implemented
on the host image into the containers.

This patch provides a facility to do this in a way that provides a new
facility for deployers to use, doesn't affect existing production
environments and is easy for us to consume in gate testing.

A new variable called 'lxc_container_cache_files' is implemented, which
is a list of dictionaries specifying the location of the file on the
deployment system, where to put it in the container cache, and what
attributes to assign the file.

An example of how to use it is included in the role's defaults as a comment.

Change-Id: Ia76b3a791239a07db1cb93636b7d1e23a6a6851c

defaults/main.yml

@@ -116,3 +116,10 @@ lxc_cache_validate_certs: "yes"
 #     name: "trusty.tgz"
 #     sha256sum: "56c6a6e132ea7d10be2f3e8104f47136ccf408b30e362133f0dc4a0a9adb4d0c"
 #     chroot_path: trusty/rootfs-amd64
+
+# A list of files may be copied into the container image cache during its preparation.
+# Example:
+#   lxc_container_cache_files:
+#     - src: "/etc/openstack_deploy/files/etc/issue"
+#       dest: "/etc/issue"
+lxc_container_cache_files: []

tasks/lxc_cache_preparation.yml

@@ -13,6 +13,20 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+- name: Copy files from deployment host to the container cache
+  copy:
+    src: "{{ item[1].src }}"
+    dest: "{{ lxc_container_cache_path }}/{{ item[0].chroot_path }}/{{ item[1].dest }}"
+    owner: "{{ item[1].owner | default('root') }}"
+    group: "{{ item[1].group | default('root') }}"
+    mode: "{{ item[1].mode | default('644') }}"
+  with_nested:
+    - lxc_container_caches
+    - lxc_container_cache_files
+  tags:
+    - lxc-cache
+    - lxc-cache-copy-files
+
 - name: Create apt repos in the cached container
   template:
     src: sources.list.j2

tests/files/container-file-copy-test.txt

@@ -0,0 +1 @@
+This is a test file to verify that the container cache file copy worked.

tests/test.yml

@@ -42,6 +42,9 @@
           name: "trusty.tgz"
           sha256sum: "56c6a6e132ea7d10be2f3e8104f47136ccf408b30e362133f0dc4a0a9adb4d0c"
           chroot_path: trusty/rootfs-amd64
+      lxc_container_cache_files:
+        - src: files/container-file-copy-test.txt
+          dest: /tmp/file-copied-from-deployment-host.txt
   post_tasks:
     - name: Open sysctl file
       slurp:
@@ -72,6 +75,14 @@
       shell: |
         cat files/expected-lxc-net-bridge.cfg
       register: expected_interface_file
+    - name: Get the deployed test file from the container cache
+      slurp:
+        src: /var/cache/lxc/trusty/rootfs-amd64/tmp/file-copied-from-deployment-host.txt
+      register: copied_file
+    - name: Get the expected test file which should have been copied
+      slurp:
+        src: files/container-file-copy-test.txt
+      register: expected_copied_file
     - name: Get bridge interface facts
       setup:
         filter: ansible_lxcbr0
@@ -84,4 +95,5 @@
           - "container_cache_dir.stat.isdir"
           - "container_tar_file.stat.exists"
           - "interface_file.stdout | match(expected_interface_file.stdout)"
+          - "copied_file.content | match(expected_copied_file.content)"
           - "lxcbr0_facts.ansible_facts.ansible_lxcbr0.ipv4.address | match('10.100.100.1')"