Add release helper script (#9713)

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>
Co-authored-by: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com>

3 files changed, 252 insertions, 0 deletions

diff --git a/changelog.d/9713.misc b/changelog.d/9713.misc
new file mode 100644
index 0000000000..908e7a2459
--- /dev/null
+++ b/changelog.d/9713.misc
@@ -0,0 +1 @@
+Add release helper script for automating part of the Synapse release process.
diff --git a/scripts-dev/release.py b/scripts-dev/release.py
new file mode 100755
index 0000000000..1042fa48bc
--- /dev/null
+++ b/scripts-dev/release.py
@@ -0,0 +1,244 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+# Copyright 2020 The Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""An interactive script for doing a release. See `run()` below.
+"""
+
+import subprocess
+import sys
+from typing import Optional
+
+import click
+import git
+from packaging import version
+from redbaron import RedBaron
+
+
+@click.command()
+def run():
+    """An interactive script to walk through the initial stages of creating a
+    release, including creating release branch, updating changelog and pushing to
+    GitHub.
+
+    Requires the dev dependencies be installed, which can be done via:
+
+        pip install -e .[dev]
+
+    """
+
+    # Make sure we're in a git repo.
+    try:
+        repo = git.Repo()
+    except git.InvalidGitRepositoryError:
+        raise click.ClickException("Not in Synapse repo.")
+
+    if repo.is_dirty():
+        raise click.ClickException("Uncommitted changes exist.")
+
+    click.secho("Updating git repo...")
+    repo.remote().fetch()
+
+    # Parse the AST and load the `__version__` node so that we can edit it
+    # later.
+    with open("synapse/__init__.py") as f:
+        red = RedBaron(f.read())
+
+    version_node = None
+    for node in red:
+        if node.type != "assignment":
+            continue
+
+        if node.target.type != "name":
+            continue
+
+        if node.target.value != "__version__":
+            continue
+
+        version_node = node
+        break
+
+    if not version_node:
+        print("Failed to find '__version__' definition in synapse/__init__.py")
+        sys.exit(1)
+
+    # Parse the current version.
+    current_version = version.parse(version_node.value.value.strip('"'))
+    assert isinstance(current_version, version.Version)
+
+    # Figure out what sort of release we're doing and calcuate the new version.
+    rc = click.confirm("RC", default=True)
+    if current_version.pre:
+        # If the current version is an RC we don't need to bump any of the
+        # version numbers (other than the RC number).
+        base_version = "{}.{}.{}".format(
+            current_version.major,
+            current_version.minor,
+            current_version.micro,
+        )
+
+        if rc:
+            new_version = "{}.{}.{}rc{}".format(
+                current_version.major,
+                current_version.minor,
+                current_version.micro,
+                current_version.pre[1] + 1,
+            )
+        else:
+            new_version = base_version
+    else:
+        # If this is a new release cycle then we need to know if its a major
+        # version bump or a hotfix.
+        release_type = click.prompt(
+            "Release type",
+            type=click.Choice(("major", "hotfix")),
+            show_choices=True,
+            default="major",
+        )
+
+        if release_type == "major":
+            base_version = new_version = "{}.{}.{}".format(
+                current_version.major,
+                current_version.minor + 1,
+                0,
+            )
+            if rc:
+                new_version = "{}.{}.{}rc1".format(
+                    current_version.major,
+                    current_version.minor + 1,
+                    0,
+                )
+
+        else:
+            base_version = new_version = "{}.{}.{}".format(
+                current_version.major,
+                current_version.minor,
+                current_version.micro + 1,
+            )
+            if rc:
+                new_version = "{}.{}.{}rc1".format(
+                    current_version.major,
+                    current_version.minor,
+                    current_version.micro + 1,
+                )
+
+    # Confirm the calculated version is OK.
+    if not click.confirm(f"Create new version: {new_version}?", default=True):
+        click.get_current_context().abort()
+
+    # Switch to the release branch.
+    release_branch_name = f"release-v{base_version}"
+    release_branch = find_ref(repo, release_branch_name)
+    if release_branch:
+        if release_branch.is_remote():
+            # If the release branch only exists on the remote we check it out
+            # locally.
+            repo.git.checkout(release_branch_name)
+            release_branch = repo.active_branch
+    else:
+        # If a branch doesn't exist we create one. We ask which one branch it
+        # should be based off, defaulting to sensible values depending on the
+        # release type.
+        if current_version.is_prerelease:
+            default = release_branch_name
+        elif release_type == "major":
+            default = "develop"
+        else:
+            default = "master"
+
+        branch_name = click.prompt(
+            "Which branch should the release be based on?", default=default
+        )
+
+        base_branch = find_ref(repo, branch_name)
+        if not base_branch:
+            print(f"Could not find base branch {branch_name}!")
+            click.get_current_context().abort()
+
+        # Check out the base branch and ensure it's up to date
+        repo.head.reference = base_branch
+        repo.head.reset(index=True, working_tree=True)
+        if not base_branch.is_remote():
+            update_branch(repo)
+
+        # Create the new release branch
+        release_branch = repo.create_head(release_branch_name, commit=base_branch)
+
+    # Switch to the release branch and ensure its up to date.
+    repo.git.checkout(release_branch_name)
+    update_branch(repo)
+
+    # Update the `__version__` variable and write it back to the file.
+    version_node.value = '"' + new_version + '"'
+    with open("synapse/__init__.py", "w") as f:
+        f.write(red.dumps())
+
+    # Generate changelogs
+    subprocess.run("python3 -m towncrier", shell=True)
+
+    # Generate debian changelogs if its not an RC.
+    if not rc:
+        subprocess.run(
+            f'dch -M -v {new_version} "New synapse release {new_version}."', shell=True
+        )
+        subprocess.run('dch -M -r -D stable ""', shell=True)
+
+    # Show the user the changes and ask if they want to edit the change log.
+    repo.git.add("-u")
+    subprocess.run("git diff --cached", shell=True)
+
+    if click.confirm("Edit changelog?", default=False):
+        click.edit(filename="CHANGES.md")
+
+    # Commit the changes.
+    repo.git.add("-u")
+    repo.git.commit(f"-m {new_version}")
+
+    # We give the option to bail here in case the user wants to make sure things
+    # are OK before pushing.
+    if not click.confirm("Push branch to github?", default=True):
+        print("")
+        print("Run when ready to push:")
+        print("")
+        print(f"\tgit push -u {repo.remote().name} {repo.active_branch.name}")
+        print("")
+        sys.exit(0)
+
+    # Otherwise, push and open the changelog in the browser.
+    repo.git.push("-u", repo.remote().name, repo.active_branch.name)
+
+    click.launch(
+        f"https://github.com/matrix-org/synapse/blob/{repo.active_branch.name}/CHANGES.md"
+    )
+
+
+def find_ref(repo: git.Repo, ref_name: str) -> Optional[git.HEAD]:
+    """Find the branch/ref, looking first locally then in the remote."""
+    if ref_name in repo.refs:
+        return repo.refs[ref_name]
+    elif ref_name in repo.remote().refs:
+        return repo.remote().refs[ref_name]
+    else:
+        return None
+
+
+def update_branch(repo: git.Repo):
+    """Ensure branch is up to date if it has a remote"""
+    if repo.active_branch.tracking_branch():
+        repo.git.merge(repo.active_branch.tracking_branch().name)
+
+
+if __name__ == "__main__":
+    run()
diff --git a/setup.py b/setup.py
index 4530df348a..e2e488761d 100755
--- a/setup.py
+++ b/setup.py
@@ -103,6 +103,13 @@ CONDITIONAL_REQUIREMENTS["lint"] = [
     "flake8",
 ]
 
+CONDITIONAL_REQUIREMENTS["dev"] = CONDITIONAL_REQUIREMENTS["lint"] + [
+    # The following are used by the release script
+    "click==7.1.2",
+    "redbaron==0.9.2",
+    "GitPython==3.1.14",
+]
+
 CONDITIONAL_REQUIREMENTS["mypy"] = ["mypy==0.812", "mypy-zope==0.2.13"]
 
 # Dependencies which are exclusively required by unit test code. This is