Cirrus: Use imgts container to record metadata

Make use of the built imgts container image to track
VM image usage statistics for every automation run.

Also update and add small check to the gate test
that verifies expected formatting/content of the
`.cirrus.yml` file WRT VM Image names.

Signed-off-by: Chris Evich <cevich@redhat.com>

contrib/cirrus/README.md

@@ -33,6 +33,17 @@ task (pass or fail) is set based on the exit status of the last script to execut
    the vendor.conf, the code and the vendored packages in ./vendor are in sync
    at all times.
 
+### ``meta`` Task
+
+***N/B: Steps below are performed by automation***
+
+1. Launch a container built from definition in ``./contrib/imgts``.
+
+2. Update VM Image metadata to help track usage across all automation.
+
+4. Always exits successfully unless there's a major problem.
+
+
 ### ``testing`` Task
 
 ***N/B: Steps below are performed by automation***

contrib/cirrus/test/test_dot_cirrus_yaml.py

@@ -0,0 +1,78 @@
+#!/bin/env python3
+
+import sys
+import os
+import os.path
+import unittest
+import warnings
+import yaml
+
+class TestCaseBase(unittest.TestCase):
+
+    SCRIPT_PATH = os.path.realpath((os.path.dirname(sys.argv[0])))
+    CIRRUS_WORKING_DIR = os.environ.get('CIRRUS_WORKING_DIR',
+                                        '{0}/../../../'.format(SCRIPT_PATH))
+
+    def setUp(self):
+        os.chdir(self.CIRRUS_WORKING_DIR)
+
+
+class TestCirrusYAML(TestCaseBase):
+
+    IMAGE_NAME_SUFFIX = '_CACHE_IMAGE_NAME'
+    ACTIVE_IMAGES_NAME = 'ACTIVE_CACHE_IMAGE_NAMES'
+
+    def setUp(self):
+        TestCirrusYAML._cirrus = None
+        super().setUp()
+
+    @property
+    def cirrus(self):
+        if TestCirrusYAML._cirrus is None:
+            with warnings.catch_warnings():
+                warnings.filterwarnings("ignore",category=DeprecationWarning)
+                with open('.cirrus.yml', "r") as dot_cirrus_dot_yaml:
+                    TestCirrusYAML._cirrus = yaml.load(dot_cirrus_dot_yaml)
+        return TestCirrusYAML._cirrus
+
+    def _assert_get_cache_image_names(self, env):
+        inames = set([key for key in env.keys()
+                      if key.endswith(self.IMAGE_NAME_SUFFIX)])
+        self.assertNotEqual(inames, set())
+
+        ivalues = set([value for key, value in env.items()
+                       if key in inames])
+        self.assertNotEqual(ivalues, set())
+        return ivalues
+
+    def _assert_get_subdct(self, key, dct):
+        self.assertIn(key, dct)
+        return dct[key]
+
+    def test_parse_yaml(self):
+        self.assertIsInstance(self.cirrus, dict)
+
+    def test_active_cache_image_names(self):
+        env = self._assert_get_subdct('env', self.cirrus)
+        acin = self._assert_get_subdct(self.ACTIVE_IMAGES_NAME, env)
+
+        for ivalue in self._assert_get_cache_image_names(env):
+            self.assertIn(ivalue, acin,
+                          "The '{}' sub-key of 'env' should contain this among"
+                          " its space-separated values."
+                          "".format(self.ACTIVE_IMAGES_NAME))
+
+
+    def test_cache_image_names_active(self):
+        env = self._assert_get_subdct('env', self.cirrus)
+        ivalues = self._assert_get_cache_image_names(env)
+
+        for avalue in set(self._assert_get_subdct(self.ACTIVE_IMAGES_NAME, env).split()):
+            self.assertIn(avalue, ivalues,
+                          "All space-separated values in the '{}' sub-key"
+                          " of 'env' must also be used in a key with a '{}' suffix."
+                          "".format(self.ACTIVE_IMAGES_NAME, self.IMAGE_NAME_SUFFIX))
+
+
+if __name__ == '__main__':
+    unittest.main(failfast=True, catchbreak=True, verbosity=0)

contrib/gate/Dockerfile

@@ -29,6 +29,7 @@ RUN dnf -y install \
       python3-dateutil \
       python3-psutil \
       python3-pytoml \
+      python3-pyyaml \
       python3-varlink \
       skopeo-containers \
       slirp4netns \