Add script to check for Dockerfile coverage

util/check_dockerfile_coverage.py

+import yaml
+import os
+import pathlib2
+import itertools
+import argparse
+import logging
+import sys
+
+TRAVIS_BUILD_DIR = os.environ.get("TRAVIS_BUILD_DIR")
+CONFIG_FILE_PATH = pathlib2.Path(TRAVIS_BUILD_DIR, "util", "parsefiles_config.yml")
+LOGGER = logging.getLogger(__name__)
+
+def check_coverage(containers):
+    # open config file containing container weights
+    config_file_path = pathlib2.Path(CONFIG_FILE_PATH)
+
+    with (config_file_path.open(mode='r')) as file:
+        try:
+            config = yaml.load(file)
+        except yaml.YAMLError, exc:
+            LOGGER.error("error in configuration file: %s" % str(exc))
+            sys.exit(1)
+
+    # get container weights
+    weights = config.get("weights")
+
+    # convert all containers in config file to a list of tuples (<container>, <weight>)
+    weights_list = [x.items() for x in weights]
+    weights_list = list(itertools.chain.from_iterable(weights_list))
+
+    # performs intersection between weighted containers and input containers
+    used_containers = [x for x in weights_list if x[0] in containers]
+
+    # determine which Dockerfiles are not covered; i.e. the set difference of the Dockerfiles to build minus the Dockerfile
+    # available to be built is non-empty
+    uncovered = set(containers) - set([x[0] for x in used_containers])
+
+    # exit with error code if uncovered Dockerfiles exist
+    if uncovered:
+        LOGGER.error("The following Dockerfiles are not described in the parsefiles_config.yml file: {}. Please see the following documentation on how to add Dockerfile ranks to the configuration file: {}".format(uncovered, "https://github.com/edx/configuration/blob/master/util/README.md"))
+        sys.exit(1)
+
+def arg_parse():
+
+    parser = argparse.ArgumentParser(description = 'Given a list of containers as input and a number of shards, '
+        'finds an approximation of the optimal distribution of the containers over the shards, provided a set of hard-coded weights '
+        'in parsefiles_config.yml.')
+    parser.add_argument('containers', help = "the Dockerfiles that need to be built as the result of some commit change and whose coverage is checked")
+
+    return parser.parse_args()
+
+if __name__ == '__main__':
+
+    args = arg_parse()
+
+    # configure logging
+    logging.basicConfig()
+
+    containers = []
+
+    for word in args.containers.split():
+        containers.append(word)
+
+    check_coverage(containers)