Use the 'real' name for the LXC image

The Open Build Service repository for the Leap 15.0 LXC image returns
a metalink which causes aria2c to download 2 files. The first is an
empty file (the metalink) and the second is the actual LXC image. The
name of the second file changes frequently.

This change uses the `--on-download-complete` callback of aria2c to
call a helper script which links the expected filename to the actual
filename.

Change-Id: I9a2bc7ded20f772af82956a81a9864c7ee17039c
Signed-off-by: Nicolas Bock <nicolas.bock@suse.com>

tasks/lxc_cache_prestage.yml

@@ -45,6 +45,14 @@
   set_fact:
     cache_basename: "{{ lxc_hosts_container_image_url | basename }}"
 
+- name: Create aria2c output script
+  template:
+    src: aria2c-download-helper.sh.j2
+    dest: /usr/local/bin/aria2c-download-helper.sh
+    owner: "root"
+    group: "root"
+    mode: "0755"
+
 - name: Pre-stage the LXC image on the system
   shell: >
     aria2c
@@ -53,6 +61,8 @@
     --dir=/tmp
     --out={{ cache_basename }}
     --check-certificate={{ (lxc_hosts_validate_certs | bool) | lower }}
+    --follow-metalink=mem
+    --on-download-complete=/usr/local/bin/aria2c-download-helper.sh
     {{ lxc_hosts_container_image_url }}
     > /var/log/aria2c-image-prestage.log 2>&1
   args:

tasks/lxc_install_zypper.yml

@@ -63,12 +63,3 @@
     enabled: "yes"
   tags:
     - lxc_hosts-config
-
-- name: Determine latest openSUSE container build information (Leap 15)
-  # NOTE(hwoarang) The build ID changes all the time so we need to have a hack to determine the latest one
-  # NOTE(evrardjp) You can still build using your own image by setting lxc_hosts_container_image_url in user_variables.
-  # NOTE(noonedeadpunk) While suse has static metalink which allows to get to the most recent build,
-  # aria2c do not save files provided by metalinks under expected names, as --out do not work for them.
-  shell: |
-      curl -s {{ _lxc_hosts_container_image_url_base }} | grep -P -o '{{ ansible_architecture }}.*?lxc.*?Build.*?xz' | head -n 1
-  register: _lxc_opensuse_image_build_info

templates/aria2c-download-helper.sh.j2

@@ -0,0 +1,10 @@
+#!/bin/bash
+
+set -x -e
+
+real_name="$3"
+link_name="/tmp/{{ cache_basename }}"
+
+if [[ ${real_name} != ${link_name} ]]; then
+  ln --symbolic "${real_name}" "${link_name}"
+fi

vars/suse.yml

@@ -15,9 +15,7 @@
 # limitations under the License.
 
 _lxc_hosts_container_image_url_base: "https://download.opensuse.org/repositories/Virtualization:/containers:/images:/openSUSE-Leap-{{ ansible_distribution_version }}/containers/"
-# If you want to specify your own image when using SUSE, please override
-# in your extra variables lxc_hosts_container_image_url.
-_lxc_hosts_container_image_url: "{{ _lxc_hosts_container_image_url_base }}opensuse-leap-image.{{ _lxc_opensuse_image_build_info.stdout }}"
+_lxc_hosts_container_image_url: "{{ _lxc_hosts_container_image_url_base }}opensuse-leap-image.x86_64-{{ ansible_distribution_version }}.0.tar.xz"
 
 _lxc_cache_map:
   distro: opensuse