[circleci] Add dockerhub auth env vars to CI (#2559)

Add in the org docker username / password and a login command to
release-publishing CI jobs

.circleci/config.yml

@@ -201,6 +201,10 @@ windows_environment: &windows_environment
   BUCK_NUM_THREADS: 3
   BUCK_PEX_LOCATION: "./new_buck.pex"
 
+dockerhub: &dockerhub
+  context:
+    - DOCKERHUB_TOKEN
+
 tags_only_filter: &tags_only_filter
   filters:
     tags:
@@ -1639,11 +1643,11 @@ workflows:
   publish_jobs:
     jobs:
       - macos_publish_release:
-          <<: *tags_only_filter
+          <<: [*tags_only_filter, *dockerhub]
       - linux_publish_release:
-          <<: *tags_only_filter
+          <<: [*tags_only_filter, *dockerhub]
       - windows_publish_release:
-          <<: *tags_only_filter
+          <<: [*tags_only_filter, *dockerhub]
       - publish_docs:
           requires:
             - linux_publish_release

tools/release/publish_release.py

@@ -221,6 +221,11 @@ def parse_args(args):
             "https://github.com/chocolatey/chocolatey.org/issues/584"
         ),
     )
+    parser.add_argument(
+        "--docker-login",
+        action="store_true",
+        help="If set, run 'docker login' using DOCKERHUB_USERNAME and DOCKERHUB_TOKEN",
+    )
     parsed_kwargs = dict(parser.parse_args(args)._get_kwargs())
     if parsed_kwargs["deb_file"]:
         parsed_kwargs["build_deb"] = False
@@ -283,6 +288,15 @@ def validate_repo_upstream(args):
         )
 
 
+def docker_login():
+    username = os.environ.get("DOCKERHUB_USERNAME")
+    token = os.environ.get("DOCKERHUB_TOKEN")
+    if username and token:
+        run(["docker", "login", "--username", username, "--password-stdin"], input=token)
+    else:
+        logging.error("Both DOCKERHUB_USERNAME and DOCKERHUB_TOKEN must be set to login to dockerhub")
+
+
 def validate_environment(args):
     """ Make sure we can build """
 
@@ -410,6 +424,10 @@ def main():
     github_token = (
         args.github_token if args.github_token else get_token(args.github_token_file)
     )
+
+    if args.docker_login:
+        docker_login()
+
     if args.chocolatey_publish:
         chocolatey_token = (
             args.chocolatey_token