Add support for gzipping static ARA reports

The ARA web application was designed to work properly when fully
gzipped with the proper mimetypes so let's add support for doing
that.

Change-Id: Ic1914c840f5a75e7da07494fb87c2167ae7bed68

roles/emit-ara-html/README.rst

@@ -1 +1,14 @@
-Have ara generate html logs if ara and ara data are both present.
+Have ARA generate html logs if ARA and ARA data are both present.
+
+**Role Variables**
+
+.. zuul:rolevar:: ara_compress_html
+
+   Whether to compress the ARA HTML output or not.
+   Defaults to ``true``.
+
+.. tip::
+   Make sure the web server is configured to set the required mimetypes_ in
+   order to serve gzipped content properly.
+
+.. _mimetypes: https://git.openstack.org/cgit/openstack-infra/puppet-openstackci/tree/templates/logs.vhost.erb?id=5fe1f3d2d5e40c2458721e7dcf8631d62ea2525f#n24

roles/emit-ara-html/defaults/main.yaml

@@ -0,0 +1,2 @@
+# Whether to compress the ARA HTML output or not
+ara_compress_html: true

roles/emit-ara-html/tasks/main.yaml

@@ -1,14 +1,19 @@
-- name: Check for ara db
+- name: Check for ARA db
   stat:
     path: "{{ zuul.executor.work_root }}/.ara/ansible.sqlite"
   register: ara_db_stat
 
-- name: Check for ara install
+- name: Check for ARA install
   command: which ara
   ignore_errors: yes
   register: ara_command_type
   when: ara_db_stat.stat.exists
 
-- name: Generate ara html output
+- name: Generate ARA html output
   command: "ara generate html {{ zuul.executor.log_root }}/ara"
   when: ara_command_type|succeeded and not ara_command_type|skipped
+
+- name: Compress ARA html output
+  archive:
+    path: "{{ zuul.executor.log_root }}/ara"
+  when: ara_compress_html | bool