Make several changes in the release and CI setup. (#509)

* Make several changes in the release and CI setup.

- Remove .travis/ directory completely.
- Update deploy.py script to tag with major.minor version
  and remove the v in the tag which it didn't before.
- Fix the CircleCI cron setup.

* Update config.yml

* Use buildkit if possible.

* Use machine executor which supports buildkit.

* Remove setup docker step

* Use newer image.

* Use buildkit syntax for caching pip dependencies.

This should significantly speed up the build process by not having
to build python wheels multiple times.

* Use plain output from buildkit

* Make deploy script work with Python 2.7

Also cache python deps across builds.

* Fix more python3 things

* Install dependency in python3

deploy.py

@@ -0,0 +1,148 @@
+#! /usr/bin/env python
+
+# Author: Abhilash Raj
+# 
+# This is the primary deployment script for the docker-mailman repo. It does
+# deployment for stable and rolling releases both. It should be *always* invoked
+# and it will make the deployment decision based on the environment variables
+# that it sees.
+#
+# There are two kinds of deploymnets primarily:
+# 1. Rolling tags, which are built from each commit. These are typically run 
+#    in CI every day as well. These always update the "rolling" tag in the
+#    docker registry.
+# 2. Stable tags, which are built from git tags with "va.b.c" tags. We don't
+#    do the tag verification because for now, Circle CI does this for us. We
+#    will tag and release a stable version whenever the right ENV var is set.
+#
+# Publishing:
+# We are typically publishing all the images to three repositories:
+# 1. Docker Hub: This is now rate-limited and might cause issues for people
+#    pulling too frequently.
+# 2. Quay: This is an old registry that we started publishing too, so let's
+#    continue publishing here too.
+# 3. Github Registry: This is the newest one in the mix and supports free
+#    uploads and downloads (without very strict rate limits like Dockerhub.)
+
+import os
+import subprocess
+from packaging import version
+
+#: Default user, which owns the repositories.
+USER = 'maxking'
+
+TAG_VAR = 'CIRCLE_TAG'
+BRANCH_VAR = 'CIRCLE_BRANCH'
+PRIMARY_BRANCH = 'main'
+
+
+def tag(original, final):
+    """Tag the source image with final tag."""
+    try:
+        print('Tagging {0} to {1}'.format(original, final))
+        subprocess.run(
+            ['docker', 'tag', original, final],
+            check=True,
+        )
+    except subprocess.CalledProcessError:
+        print('Failed to tag {0}'.format(original))
+
+
+def login(url):
+    """Login to the registry."""
+    if 'quay' in url.lower():
+        password = os.environ['QUAY_PASSWORD']
+    elif 'docker' in url.lower():
+        password = os.environ['DOCKER_PASSWORD']
+    elif 'ghcr' in url.lower():
+        password = os.environ['GITHUB_PASSWORD']
+    else:
+        print('Password not found for {0}'.format(url))
+        return None
+    print('Logging in to {0}'.format(url))
+    subprocess.run(
+        ['docker', 'login', '-u', USER, '-p', password, url],
+        check=True
+    )
+    print('Logged in to {0}'.format(url))
+
+
+def push(image):
+    """Push all the images."""
+    print('Pushing {}'.format(image))
+    subprocess.run(['docker', 'push', image], check=True)
+
+
+def tag_and_push(image_names, url, img_tag):
+    """Given the URL to repository, tag and push the images."""
+    # Tag recently built images.
+    source, final = image_names
+    tag(source, final)
+    # Finall, push all the images.
+    push(final)
+
+
+def get_tag_without_patch(tag):
+    """Given A.B.C return A.B"""
+    v = version.parse(tag)
+    return '{}.{}'.format(v.major, v.minor)
+
+
+def get_urls(url, img_tag):
+    core = ('maxking/mailman-core:rolling',
+            '{0}/maxking/mailman-core:{1}'.format(url, img_tag))
+    web = ('maxking/mailman-web:rolling',
+        '{0}/maxking/mailman-web:{1}'.format(url, img_tag))
+    postorius = ('maxking/postorius:rolling',
+        '{0}/maxking/postorius:{1}'.format(url, img_tag))
+
+    return (core, web, postorius)
+                     
+
+
+def main():
+    """Primary entrypoint to this script."""
+    # Boolean signifying if this is a stable release tag or just a branch.
+    is_release = False
+
+    if os.environ.get(TAG_VAR) not in (None, ''):
+        img_tag = os.environ.get(TAG_VAR)
+        # Released versions are tagged vA.B.C, so remove
+        # v from the tag when creating the release.
+        if img_tag.startswith('v'):
+            img_tag = img_tag[1:]
+            is_release = True
+
+    elif os.environ.get(BRANCH_VAR) == PRIMARY_BRANCH:
+        img_tag = 'rolling'
+    else:
+        print('Not running on {PRIMARY_BRANCH} branch or Git tag so not publishing...'.format(
+            PRIMARY_BRANCH=PRIMARY_BRANCH))
+        exit(0)
+
+    # All the registries we are pushing to.
+    for url in ('quay.io', 'docker.io', 'ghcr.io'):
+
+        try:
+            login(url)
+        except subprocess.CalledProcessError:
+            print('Failed to login to {}'.format(url))
+            continue
+        
+        # Push all the container images.
+        for each in get_urls(url, img_tag):
+            tag_and_push(each, url, img_tag)
+
+        # If this is a release tag, tag them also with a.b version.
+        if is_release:
+            rel_tag = get_tag_without_patch(img_tag)
+            for each in get_urls(url, rel_tag):
+                tag_and_push(each, url, rel_tag)
+
+
+
+if __name__ == '__main__':
+
+    main()
+
+