Upload nightly builds to Github Releases

This change extends the `mach upload-nightly` command to
publish the nightly builds for all platforms as GH Release
assets.

The GH releases are made on a separate repository so
that we can persist older nightly builds without having
to accumulate git tags for them.

Some design tradeoffs in this approach are:
1. To allow the 'latest' link from servo.org to remain stable,
the release assets are named 'servo-latest.{ext}' instead of
containing the release tag/date.
2. The release is created as draft and published atomically
when all platforms have been built successfully. This allows
us to link to the 'latest' alias from servo.org while
gauranteeing that it contains builds for all platforms.
The other option here would be to have code in servo.org UI
that uses GH API to find the most recent release with a
successful build for a given platform.
3. The tags in the nightly repo are all based on the same
commit that has no relation to servo code base.

Signed-off-by: Mukilan Thiyagarajan <me@mukilan.in>

python/requirements.txt

@@ -23,6 +23,7 @@ colorama == 0.3.7
 
 # For package uploading
 boto3 == 1.17.27
+PyGithub == 1.58.1
 
 # Default root CAs on Windows CI do not trust CloudFront certificates,
 # connecting to https://static.rust-lang.org would fail:

python/servo/package_commands.py

@@ -10,6 +10,8 @@
 from __future__ import absolute_import, print_function, unicode_literals
 
 from datetime import datetime
+from github import Github
+
 import base64
 import hashlib
 import io
@@ -594,7 +596,11 @@ class PackageCommands(CommandBase):
     @CommandArgument('--secret-from-environment',
                      action='store_true',
                      help='Retrieve the appropriate secrets from the environment.')
-    def upload_nightly(self, platform, secret_from_environment):
+    @CommandArgument('--github-release-id',
+                     default=None,
+                     type=int,
+                     help='The github release to upload the nightly builds.')
+    def upload_nightly(self, platform, secret_from_environment, github_release_id):
         import boto3
 
         def get_s3_secret():
@@ -612,7 +618,24 @@ class PackageCommands(CommandBase):
                 path.basename(package)
             )
 
-        def upload_to_s3(platform, package, timestamp):
+        def upload_to_github_release(platform, package, package_hash_fileobj):
+            if not github_release_id:
+                return
+            extension = path.basename(package).partition('.')[2]
+            g = Github(os.environ['NIGHTLY_REPO_TOKEN'])
+            nightly_repo = g.get_repo(os.environ['NIGHTLY_REPO'])
+            release = nightly_repo.get_release(github_release_id)
+            if '2020' in platform:
+                asset_name = f'servo-latest-layout-2020.{extension}'
+            else:
+                asset_name = f'servo-latest.{extension}'
+            release.upload_asset(package, name=asset_name)
+            release.upload_asset_from_memory(
+                package_hash_fileobj,
+                package_hash_fileobj.getbuffer().nbytes,
+                name=f'{asset_name}.sha256')
+
+        def upload_to_s3(platform, package, package_hash_fileobj, timestamp):
             (aws_access_key, aws_secret_access_key) = get_s3_secret()
             s3 = boto3.client(
                 's3',
@@ -635,17 +658,6 @@ class PackageCommands(CommandBase):
             extension = path.basename(package).partition('.')[2]
             latest_upload_key = '{}/servo-latest.{}'.format(nightly_dir, extension)
 
-            # Compute the hash
-            SHA_BUF_SIZE = 1048576  # read in 1 MiB chunks
-            sha256_digest = hashlib.sha256()
-            with open(package, 'rb') as package_file:
-                while True:
-                    data = package_file.read(SHA_BUF_SIZE)
-                    if not data:
-                        break
-                    sha256_digest.update(data)
-            package_hash = sha256_digest.hexdigest()
-            package_hash_fileobj = io.BytesIO(package_hash.encode('utf-8'))
             latest_hash_upload_key = f'{latest_upload_key}.sha256'
 
             s3.upload_file(package, BUCKET, package_upload_key)
@@ -763,7 +775,21 @@ class PackageCommands(CommandBase):
                     package
                 ), file=sys.stderr)
                 return 1
-            upload_to_s3(platform, package, timestamp)
+
+            # Compute the hash
+            SHA_BUF_SIZE = 1048576  # read in 1 MiB chunks
+            sha256_digest = hashlib.sha256()
+            with open(package, 'rb') as package_file:
+                while True:
+                    data = package_file.read(SHA_BUF_SIZE)
+                    if not data:
+                        break
+                    sha256_digest.update(data)
+            package_hash = sha256_digest.hexdigest()
+            package_hash_fileobj = io.BytesIO(package_hash.encode('utf-8'))
+
+            upload_to_s3(platform, package, package_hash_fileobj, timestamp)
+            upload_to_github_release(platform, package, package_hash_fileobj)
 
         if platform == 'maven':
             for package in PACKAGES[platform]: