Add support for blacklist file for Zuul jobs

Currently there is tempest_test_regex that can be used to select or
ignore tests, however when the list is complex it can become complex to
maintain and define. For such complex scenarios is that the blacklist
file exist.

This patch adds support for the blacklist file in Zuul jobs.

Change-Id: Ib63955446ea59d81d0d882704666dcce4a625526

roles/run-tempest/README.rst

@@ -29,6 +29,12 @@ Run Tempest
                # Line with only a comment.
                (tempest\.(api|scenario|thirdparty)).*$    # Run only api scenario and third party
 
+.. zuul:rolevar:: tempest_test_blacklist
+
+   Specifies a blacklist file to skip tests that are not needed.
+
+   Pass a full path to the file.
+
 .. zuul:rolevar:: tox_envlist
    :default: smoke
 

roles/run-tempest/tasks/main.yaml

@@ -20,8 +20,22 @@
     default_concurrency: "{{ num_cores|int // 2 }}"
   when: num_cores|int > 3
 
+- when:
+    - tempest_test_blacklist is defined
+  block:
+    - name: Check for test blacklist file
+      stat:
+        path: "{{ tempest_test_blacklist }}"
+      register:
+        blacklist_stat
+
+    - name: Build blacklist option
+      set_fact:
+        blacklist_option: "--blacklist-file={{ tempest_test_blacklist|quote }}"
+      when: blacklist_stat.stat.exists
+
 - name: Run Tempest
-  command: tox -e {{tox_envlist}} -- {{tempest_test_regex|quote}} --concurrency={{tempest_concurrency|default(default_concurrency)}}
+  command: tox -e {{tox_envlist}} -- {{tempest_test_regex|quote}} {{blacklist_option|default('')}} --concurrency={{tempest_concurrency|default(default_concurrency)}}
   args:
     chdir: "{{devstack_base_dir}}/tempest"
   become: true