Add a script in travis to add a master branch status check to PRs

.travis.yml

@@ -15,6 +15,7 @@ cache:
 
 before_install:
     - make travis_up
+    - python .travis/check_master_build.py --commit $TRAVIS_COMMIT --github_status_token $GITHUB_STATUS_TOKEN --travis_api_token $TRAVIS_API_TOKEN &
 
 install:
   - docker exec -t discovery bash -c 'apt update && apt install -y xvfb firefox gettext wget'

.travis/check_master_build.py

+"""
+Adds a status check to a github PR which check whether or not the last
+build on master passed or failed.
+
+Uses the Travis API to get the latest master build state and build url.
+The Github Status API is then used to add a status to the given commit
+hash.
+
+A github_status_token and travis_api_token must be set up for this
+script to work. These can be configured in the travis settings
+(https://docs.travis-ci.com/user/environment-variables/#Defining-Variables-in-Repository-Settings)
+or passed as secure parameters in the travis.yml file
+(https://docs.travis-ci.com/user/environment-variables/#Defining-encrypted-variables-in-.travis.yml).
+The commit hash is provided by a Travis build as $TRAVIS_COMMIT.
+
+Example usage:
+     python .travis/check_master_build.py --commit $TRAVIS_COMMIT \
+     --github_status_token $GITHUB_STATUS_TOKEN --travis_api_token $TRAVIS_API_TOKEN
+
+"""
+import argparse
+import json
+import logging
+import sys
+import time
+import urllib.request
+import urllib.parse
+
+CHECK_MASTER_STATUS_TIMEOUT_IN_MINUTES = 25  # Should be set to how long a build usually takes.
+TRAVIS_REPO_ID = '6521695'
+
+logging.basicConfig(level=logging.INFO)
+logger = logging.getLogger("Check Master Build Log")
+
+
+def add_status_to_commit(commit, github_token, travis_token):
+    """Adds the latest master's build state to the commit's PR status checks"""
+    master_status, href = get_master_build_data(travis_token)
+    payload = build_status_api_payload(master_status, href)
+    update_github_status(commit, github_token, payload)
+
+
+def update_github_status(commit_hash, git_token, payload):
+    """
+    Update PR's for the given commit_hash
+
+    Args:
+        commit_hash (str): Status for the latest master branch build.
+        git_token (str): Token for using the github status API
+        payload (dict): Payload to be sent to github status API
+
+    Returns:
+        dict: Dict used as the POST data for the Github status API
+    """
+    logger.info("Sending Status API request for commit hash {}".format(commit_hash))
+    logger.info("POST data for Status API: {}".format(payload))
+
+    headers = {
+        'Content-Type': 'application/json',
+        'Authorization': 'token {}'.format(git_token),
+    }
+
+    url = 'https://api.github.com/repos/edx/course-discovery/statuses/{}'.format(commit_hash)
+    data = json.dumps(payload).encode('utf-8')
+    r = urllib.request.Request(url=url, headers=headers, data=data)
+    response = urllib.request.urlopen(r)
+    if response.code == 201:
+        logger.info("Github status update success")
+
+
+def build_status_api_payload(master_build_status, href):
+    """
+    Build the appropriate POST data for the github status api.
+
+    Args:
+        master_build_status (str): Status for the latest master branch build.
+        href (str): HREF for the laste master branch build.
+
+    Returns:
+        dict: Dict used as the POST data for the Github status API
+    """
+    if master_build_status == "passed":
+        state = "success"
+        message = "The latest master branch has passed CI"
+    elif master_build_status == "failed":
+        state = "failure"
+        message = "The latest master branch has failed CI"
+    elif master_build_status == "started":
+        state = "pending"
+        message = "The latest master branch is still pending"
+    else:
+        state = "pending"  # Do not fail the build if build status is unknown.
+        message = "Cannot retrieve the status of the master branch build. "
+
+    if href and "builds" not in href:
+        href = "/builds" + href.split("build")[1]  # In case Travis API returns the wrong HREF.
+    target_url = "https://travis-ci.org/edx/course-discovery" + href
+
+    return {
+        'state': state,
+        'target_url': target_url,
+        'description': message,
+        'context': "Master branch status"
+    }
+
+
+def get_master_build_data(travis_token):
+    """
+    Retrieves the build status and href of the latest master build
+
+    This method will keep trying until it receives a finished state or
+    times out.
+    """
+    finished_state = ['passed', 'failure']
+    attempts = 5
+    timeout = (CHECK_MASTER_STATUS_TIMEOUT_IN_MINUTES / attempts) * 60
+
+    status, href = call_travis_api(travis_token)
+
+    while status not in finished_state and attempts > 1:
+        logger.info("Attempting to get master build status {} more time(s).".format(attempts - 1))
+        time.sleep(timeout)
+        status, href = call_travis_api(travis_token)
+        attempts -= 1
+
+    return status, href
+
+
+def call_travis_api(travis_token):
+    """
+    Calls travis API for the latest master branch build data
+
+    Args:
+        travis_token (str): Travis API token
+
+    Returns:
+        build_state, href: The build state of the latest master branch and
+                            the href of the build.
+    """
+    headers = {
+        "Travis-API-Version": "3",
+        "Authorization": "token {}".format(travis_token),
+    }
+    url = "http://api.travis-ci.org/repo/{repo_id}/branch/master".format(repo_id=TRAVIS_REPO_ID)
+
+    req = urllib.request.Request(url=url, headers=headers)
+    response = urllib.request.urlopen(req, timeout=10)
+
+    if response.code != 200:
+        logger.error("Travis API query for master branch status was unsuccessful: {}".format(response.status_code))
+        return None, ""
+    response = response.read()
+    try:
+        response_dict = json.loads(response.decode('utf-8'))
+        build_state = response_dict['last_build']['state']
+        build_href = response_dict['last_build']['@href']
+        logger.info("Current master branch build state is '{}'".format(build_state))
+        return build_state, build_href
+    except Exception as ex:
+        logger.error("Unexpected Travis API response: {} {}".format(type(ex).__name__, ex.args))
+        logger.error(response)
+        logger.error("URL: {}".format(url))
+        return None, ""
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--commit")
+    parser.add_argument("--github_status_token", required=True, help="Github token with Status API permissions.")
+    parser.add_argument("--travis_api_token", required=True, help="Travis API token used for fetching repository data.")
+    args = parser.parse_args()
+
+    add_status_to_commit(args.commit, args.github_status_token, args.travis_api_token)
+    sys.exit(0)