Add compress capabilities to stage artifacts

Compress files and files in folders. Use gz by default.

Change-Id: I72796e64a65fe88d85168734ac881ee3ec2ce100

roles/stage-output/README.rst

@@ -47,3 +47,8 @@ intended to be used before output fetching in a base job's post-playbook.
      - log
 
      zuul.conf --(staged as)--> zuul_conf.txt
+
+.. zuul:rolevar:: stage_compress_logs
+   :default: True
+
+   When True, files staged as logs will be compressed individually.

roles/stage-output/defaults/main.yaml

@@ -1,2 +1,3 @@
 stage_dir: "{{ ansible_user_dir }}"
 extensions_to_txt:
+stage_compress_logs: true

roles/stage-output/tasks/main.yaml

@@ -19,6 +19,7 @@
   set_fact:
     source: "{{ item.stat.path }}"
     dest: "{{ item.item.value }}/{{ item.stat.path|basename|regex_replace('\\.(' + extensions_regex + ')$', '_\\1.txt') }}"
+    type: "{{ item.item.value }}"
   with_items: "{{ sources.results }}"
   when:
     - item.stat.exists
@@ -45,3 +46,17 @@
   # zuul, using command
   command: cp -pR {{ item.source}} {{ stage_dir }}/{{ item.dest }}
   with_items: "{{ all_sources }}"
+
+# NOTE(andreaf) The ansible module does not support recursive archive, so
+# using gzip is the only option here. The good bit is that gzip itself is
+# almost idempotent, as it will not compress again files with .gz extension.
+# gzip will however return 1 if any compressed file is encountered, so we
+# must ignore that (there's no specific error code).
+- name: Archive everything from docs sources
+  shell: gzip --recursive --best {{ item.dest }} || true
+  args:
+    chdir: "{{ stage_dir }}"
+  with_items: "{{ all_sources }}"
+  when:
+    - stage_compress_logs
+    - item.type == 'logs'