Put into place initial release engineering

This can release x86_64-linux binaries to staging, with ephemeral keys.
I think it's good enough to review at least at this point, so we don't
keep adding more stuff to it to make it harder to review.

Change-Id: Ie95e8f35d1252f5d014e819566f170b30eda152e

9 files changed, 653 insertions, 0 deletions

diff --git a/releng/README.md b/releng/README.md
new file mode 100644
index 000000000..cfacf4b8e
--- /dev/null
+++ b/releng/README.md
@@ -0,0 +1,132 @@
+# Release engineering
+
+This directory contains the release engineering scripts for Lix.
+
+## Release process
+
+### Prerequisites
+
+* FIXME: validation via misc tests in nixpkgs, among other things? What other
+  validation do we need before we can actually release?
+* Have a release post ready to go as a PR on the website repo.
+* No [release-blocker bugs][release-blockers].
+
+[release-blockers]: https://git.lix.systems/lix-project/lix/issues?q=&type=all&sort=&labels=145&state=open&milestone=0&project=0&assignee=0&poster=0
+
+### Process
+
+The following process can be done either against the staging environment or the
+live environment.
+
+For staging, the buckets are `staging-releases`, `staging-cache`, etc.
+
+FIXME: obtainment of signing key for signing cache paths?
+
+First, we prepare the release. `python -m releng prepare` is used for this.
+
+* Gather everything in `doc/manual/rl-next` and put it in
+  `doc/manual/src/release-notes/rl-MAJOR.md`.
+
+Then we tag the release with `python -m releng tag`:
+
+* Git HEAD is detached.
+* `officialRelease = true` is set in `flake.nix`, this is committed, and a
+  release is tagged.
+* The tag is merged back into the last branch (either `main` for new releases
+  or `release-MAJOR` for maintenance releases) with `git merge -s ours VERSION`
+  creating a history link but ignoring the tree of the release tag.
+* Git HEAD is once again detached onto the release tag.
+
+Then, we build the release artifacts with `python -m releng build`:
+
+* Source tarball is generated with `git archive`, then checksummed.
+* Manifest for `nix upgrade-nix` is produced and put in `s3://releases` at
+  `/manifest.nix` and `/lix/lix-VERSION`.
+* Release is built: `hydraJobs.binaryTarball` jobs are built, and joined into a
+  derivation that depends on all of them and adds checksum files. This and the
+  sources go into `s3://releases/lix/lix-VERSION`.
+
+At this point we have a `release/artifacts` and `release/manual` directory
+which are ready to publish, and tags ready for publication. No keys are
+required to do this part.
+
+Next, we do the publication with `python -m releng upload`:
+
+* Artifacts for this release are uploaded:
+  * s3://releases/manifest.nix, changing the default version of Lix for
+    `nix upgrade-nix`.
+  * s3://releases/lix/lix-VERSION/ gets the following contents
+    * Binary tarballs
+    * Docs: `manual/` (FIXME: should we actually do this? what about putting it
+      on docs.lix.systems? I think doing both is correct, since the Web site
+      should not be an archive of random old manuals)
+    * Docs as tarball in addition to web.
+    * Source tarball
+    * Docker image (FIXME: upload to forgejo registry and github registry [in the future][upload-docker])
+  * s3://docs/manual/lix/MAJOR
+  * s3://docs/manual/lix/stable
+
+* The tag is uploaded to the remote repo.
+* **Manually** build the installer using the scripts in the installer repo and upload.
+
+  FIXME: This currently requires a local Apple Macintosh® aarch64 computer, but
+  we could possibly automate doing it from the aarch64-darwin builder.
+* **Manually** Push the main/release branch directly to gerrit.
+* If this is a new major release, branch-off to `release-MAJOR` and push *that* branch
+  directly to gerrit as well (FIXME: special creds for doing this as a service
+  account so we don't need to have the gerrit perms to shoot ourselves in the
+  foot by default because pushing to main is bad?).
+
+  FIXME: automate branch-off to `release-*` branch.
+* **Manually** (FIXME?) switch back to the release branch, which now has the
+  correct revision.
+* Post!!
+  * Merge release blog post to [lix-website].
+  * Toot about it! https://chaos.social/@lix_project
+  * Tweet about it! https://twitter.com/lixproject
+
+[lix-website]: https://git.lix.systems/lix-project/lix-website
+
+[upload-docker]: https://git.lix.systems/lix-project/lix/issues/252
+
+### Installer
+
+The installer is cross-built to several systems from a Mac using
+`build-all.xsh` and `upload-to-lix.xsh` in the installer repo (FIXME: currently
+at least; maybe this should be moved here?) .
+
+It installs a binary tarball (FIXME: [it should be taught to substitute from
+cache instead][installer-substitute])
+from some URL; this is the `hydraJobs.binaryTarball`. The default URLs differ
+by architecture and are [configured here][tarball-urls].
+
+[installer-substitute]: https://git.lix.systems/lix-project/lix-installer/issues/13
+[tarball-urls]: https://git.lix.systems/lix-project/lix-installer/src/commit/693592ed10d421a885bec0a9dd45e87ab87eb90a/src/settings.rs#L14-L28
+
+## Infrastructure summary
+
+* releases.lix.systems (`s3://releases`):
+  * Each release gets a directory: https://releases.lix.systems/lix/lix-2.90-beta.1
+    * Binary tarballs: `nix-2.90.0-beta.1-x86_64-linux.tar.xz`, from `hydraJobs.binaryTarball`
+    * Manifest: `manifest.nix`, an attrset of the store paths by architecture.
+  * Manifest for `nix upgrade-nix` to the latest release at `/manifest.nix`.
+* cache.lix.systems (`s3://cache`):
+  * Receives all artifacts for released versions of Lix; is a plain HTTP binary cache.
+* install.lix.systems (`s3://install`):
+  ```
+  ~ » aws s3 ls s3://install/lix/
+                             PRE lix-2.90-beta.0/
+                             PRE lix-2.90-beta.1/
+                             PRE lix-2.90.0pre20240411/
+                             PRE lix-2.90.0pre20240412/
+  2024-05-05 18:59:11    6707344 lix-installer-aarch64-darwin
+  2024-05-05 18:59:16    7479768 lix-installer-aarch64-linux
+  2024-05-05 18:59:14    7982208 lix-installer-x86_64-darwin
+  2024-05-05 18:59:17    8978352 lix-installer-x86_64-linux
+
+  ~ » aws s3 ls s3://install/lix/lix-2.90-beta.1/
+  2024-05-05 18:59:01    6707344 lix-installer-aarch64-darwin
+  2024-05-05 18:59:06    7479768 lix-installer-aarch64-linux
+  2024-05-05 18:59:03    7982208 lix-installer-x86_64-darwin
+  2024-05-05 18:59:07    8978352 lix-installer-x86_64-linux
+  ```
diff --git a/releng/__init__.py b/releng/__init__.py
new file mode 100644
index 000000000..401b8e322
--- /dev/null
+++ b/releng/__init__.py
@@ -0,0 +1,17 @@
+from xonsh.main import setup
+setup()
+del setup
+
+from releng import environment
+from releng import create_release
+from releng import keys
+from releng import version
+from releng import cli
+
+def reload():
+    import importlib
+    importlib.reload(environment)
+    importlib.reload(create_release)
+    importlib.reload(keys)
+    importlib.reload(version)
+    importlib.reload(cli)
diff --git a/releng/__main__.py b/releng/__main__.py
new file mode 100644
index 000000000..31127daea
--- /dev/null
+++ b/releng/__main__.py
@@ -0,0 +1,3 @@
+from . import cli
+
+cli.main()
diff --git a/releng/cli.py b/releng/cli.py
new file mode 100644
index 000000000..7db8a80f9
--- /dev/null
+++ b/releng/cli.py
@@ -0,0 +1,73 @@
+from . import create_release
+import argparse
+import sys
+
+
+def do_build(args):
+    create_release.build_artifacts(no_check_git=args.no_check_git)
+
+
+def do_tag(args):
+    create_release.do_tag_merge(force_tag=args.force_tag,
+                                no_check_git=args.no_check_git)
+
+
+def do_upload(args):
+    create_release.setup_creds()
+    create_release.upload_artifacts(force_push_tag=args.force_push_tag,
+                                    noconfirm=args.noconfirm)
+
+def do_prepare(args):
+    create_release.prepare_release_notes()
+
+
+def main():
+    ap = argparse.ArgumentParser(description='*Lix ur release engineering*')
+
+    def fail(args):
+        ap.print_usage()
+        sys.exit(1)
+
+    ap.set_defaults(cmd=fail)
+
+    sps = ap.add_subparsers()
+
+    prepare = sps.add_parser('prepare', help='Prepares for a release by moving the release notes over.')
+    prepare.set_defaults(cmd=do_prepare)
+
+    tag = sps.add_parser(
+        'tag',
+        help=
+        'Create the tag for the current release in .version and merge it back to the current branch, then switch to it'
+    )
+    tag.add_argument('--no-check-git',
+                     action='store_true',
+                     help="Don't check git state before tagging. For testing.")
+    tag.add_argument('--force-tag',
+                     action='store_true',
+                     help='Overwrite the existing tag. For testing.')
+    tag.set_defaults(cmd=do_tag)
+
+    build = sps.add_parser(
+        'release',
+        help=
+        'Build an artifacts/ directory with the things that would be released')
+    build.add_argument(
+        '--no-check-git',
+        action='store_true',
+        help="Don't check git state before building. For testing.")
+    build.set_defaults(cmd=do_build)
+
+    upload = sps.add_parser(
+        'upload', help='Upload artifacts to cache and releases bucket')
+    upload.add_argument('--force-push-tag',
+                        action='store_true',
+                        help='Force push the tag. For testing.')
+    upload.add_argument(
+        '--noconfirm',
+        action='store_true',
+        help="Don't ask for confirmation. For testing/automation.")
+    upload.set_defaults(cmd=do_upload)
+
+    args = ap.parse_args()
+    args.cmd(args)
diff --git a/releng/create_release.xsh b/releng/create_release.xsh
new file mode 100644
index 000000000..c9725c44c
--- /dev/null
+++ b/releng/create_release.xsh
@@ -0,0 +1,297 @@
+import json
+import subprocess
+import itertools
+import textwrap
+from pathlib import Path
+import tempfile
+import hashlib
+import datetime
+from . import environment
+from . import keys
+from .version import VERSION, RELEASE_NAME, MAJOR
+
+$RAISE_SUBPROC_ERROR = True
+$XONSH_SHOW_TRACEBACK = True
+
+RELENG_ENV = environment.STAGING
+
+RELEASES_BUCKET = RELENG_ENV.releases_bucket
+CACHE_STORE = RELENG_ENV.cache_store_uri()
+REPO = RELENG_ENV.git_repo
+
+GCROOTS_DIR = Path('./release/gcroots')
+BUILT_GCROOTS_DIR = Path('./release/gcroots-build')
+DRVS_TXT = Path('./release/drvs.txt')
+ARTIFACTS = Path('./release/artifacts')
+
+RELENG_MSG = "Release created with releng/create_release.xsh"
+
+BUILD_CORES = 16
+MAX_JOBS = 2
+
+# TODO
+RELEASE_SYSTEMS = ["x86_64-linux"]
+
+
+def setup_creds():
+    key = keys.get_ephemeral_key(RELENG_ENV)
+    $AWS_SECRET_ACCESS_KEY = key.secret_key
+    $AWS_ACCESS_KEY_ID = key.id
+    $AWS_DEFAULT_REGION = 'garage'
+    $AWS_ENDPOINT_URL = environment.S3_ENDPOINT
+
+
+def git_preconditions():
+    # verify there is nothing in index ready to stage
+    proc = !(git diff-index --quiet --cached HEAD --)
+    assert proc.rtn == 0
+    # verify there is nothing *stageable* and tracked
+    proc = !(git diff-files --quiet)
+    assert proc.rtn == 0
+
+
+def official_release_commit_tag(force_tag=False):
+    print('[+] Setting officialRelease in flake.nix and tagging')
+    prev_branch = $(git symbolic-ref --short HEAD).strip()
+
+    git switch --detach
+    sed -i 's/officialRelease = false/officialRelease = true/' flake.nix
+    git add flake.nix
+    message = f'release: {VERSION} "{RELEASE_NAME}"\n\nRelease produced with releng/create_release.xsh'
+    git commit -m @(message)
+    git tag @(['-f'] if force_tag else []) -a -m @(message) @(VERSION)
+
+    return prev_branch
+
+
+def merge_to_release(prev_branch):
+    git switch @(prev_branch)
+    # Create a merge back into the release branch so that git tools understand
+    # that the release branch contains the tag, without the release commit
+    # actually influencing the tree.
+    merge_msg = textwrap.dedent("""\
+        release: merge release {VERSION} back to mainline
+
+        This merge commit returns to the previous state prior to the release but leaves the tag in the branch history.
+        {RELENG_MSG}
+    """).format(VERSION=VERSION, RELENG_MSG=RELENG_MSG)
+    git merge -m @(merge_msg) -s ours @(VERSION)
+
+
+def realise(paths: list[str]):
+    args = [
+        '--realise',
+        '--max-jobs',
+        MAX_JOBS,
+        '--cores',
+        BUILD_CORES,
+        '--log-format',
+        'bar-with-logs',
+        '--add-root',
+        BUILT_GCROOTS_DIR
+    ]
+    nix-store @(args) @(paths)
+
+
+def eval_jobs():
+    nej_output = $(nix-eval-jobs --workers 4 --gc-roots-dir @(GCROOTS_DIR) --force-recurse --flake '.#release-jobs')
+    return [x for x in (json.loads(s) for s in nej_output.strip().split('\n'))
+        if x['system'] in RELEASE_SYSTEMS
+    ]
+
+
+def upload_drv_paths_and_outputs(paths: list[str]):
+    proc = subprocess.Popen([
+            'nix',
+            'copy',
+            '-v',
+            '--to',
+            CACHE_STORE,
+            '--stdin',
+        ],
+        stdin=subprocess.PIPE,
+        env=__xonsh__.env.detype(),
+    )
+
+    proc.stdin.write('\n'.join(itertools.chain(paths, x + '^*' for x in paths)).encode())
+    proc.stdin.close()
+    rv = proc.wait()
+    if rv != 0:
+        raise subprocess.CalledProcessError(rv, proc.args)
+
+
+def make_manifest(eval_result):
+    manifest = {vs['system']: vs['outputs']['out'] for vs in eval_result}
+    def manifest_line(system, out):
+        return f'  {system} = "{out}";'
+
+    manifest_text = textwrap.dedent("""\
+        # This file was generated by releng/create_release.xsh in Lix
+        {{
+          {lines}
+        }}
+    """).format(lines='\n'.join(manifest_line(s, p) for (s, p) in manifest.items()))
+
+    return manifest_text
+
+
+def make_git_tarball(to: Path):
+    git archive --verbose --prefix=lix-@(VERSION)/ --format=tar.gz -o @(to) @(VERSION)
+
+
+def confirm(prompt, expected):
+    resp = input(prompt)
+
+    if resp != expected:
+        raise ValueError('Unconfirmed')
+
+
+def sha256_file(f: Path):
+    hasher = hashlib.sha256()
+
+    with open(f, 'rb') as h:
+        while data := h.read(1024 * 1024):
+            hasher.update(data)
+
+    return hasher.hexdigest()
+
+
+def make_artifacts_dir(eval_result, d: Path):
+    d.mkdir(exist_ok=True, parents=True)
+    version_dir = d / 'lix' / f'lix-{VERSION}'
+    version_dir.mkdir(exist_ok=True, parents=True)
+
+    tarballs_drv = next(p for p in eval_result if p['attr'] == 'tarballs')
+    cp --no-preserve=mode -r @(tarballs_drv['outputs']['out'])/* @(version_dir)
+
+    # FIXME: upgrade-nix searches for manifest.nix at root, which is rather annoying
+    with open(d / 'manifest.nix', 'w') as h:
+        h.write(make_manifest(eval_result))
+
+    with open(version_dir / 'manifest.nix', 'w') as h:
+        h.write(make_manifest(eval_result))
+
+    print('[+] Make sources tarball')
+
+    filename = f'lix-{VERSION}.tar.gz'
+    git_tarball = version_dir / filename
+    make_git_tarball(git_tarball)
+
+    file_hash = sha256_file(git_tarball)
+
+    print(f'Hash: {file_hash}')
+    with open(version_dir / f'{filename}.sha256', 'w') as h:
+        h.write(file_hash)
+
+
+def prepare_release_notes():
+    print('[+] Preparing release notes')
+    RELEASE_NOTES_PATH = Path('doc/manual/rl-next')
+
+    if RELEASE_NOTES_PATH.isdir():
+        notes_body = subprocess.check_output(['build-release-notes', '--change-authors', 'doc/manual/change-authors.yml', 'doc/manual/rl-next']).decode()
+    else:
+        # I guess nobody put release notes on their changes?
+        print('[-] Warning: seemingly missing any release notes, not worrying about it')
+        notes_body = ''
+
+    rl_path = Path(f'doc/manual/src/release-notes/rl-{MAJOR}.md')
+
+    existing_rl = ''
+    try:
+        with open(rl_path, 'r') as fh:
+            existing_rl = fh.read()
+    except FileNotFoundError:
+        pass
+
+    date = datetime.datetime.now().strftime('%Y-%m-%d')
+
+    minor_header = f'# Lix {VERSION} ({date})'
+
+    header = f'# Lix {MAJOR} "{RELEASE_NAME}"'
+    if existing_rl.startswith(header):
+        # strip the header off for minor releases
+        lines = existing_rl.splitlines()
+        header = lines[0]
+        existing_rl = '\n'.join(lines[1:])
+    else:
+        header += f' ({date})\n\n'
+
+    header += '\n' + minor_header + '\n'
+
+    notes = header
+    notes += notes_body
+    notes += "\n\n"
+    notes += existing_rl
+
+    # make pre-commit happy about one newline
+    notes = notes.rstrip()
+    notes += "\n"
+
+    with open(rl_path, 'w') as fh:
+        fh.write(notes)
+
+    commit_msg = textwrap.dedent("""\
+        release: release notes for {VERSION}
+
+        {RELENG_MSG}
+    """).format(VERSION=VERSION, RELENG_MSG=RELENG_MSG)
+
+    git add @(rl_path)
+    git rm doc/manual/rl-next/*.md
+
+    git commit -m @(commit_msg)
+
+
+def verify_are_on_tag():
+    current_tag = $(git describe --tag).strip()
+    assert current_tag == VERSION
+
+
+def upload_artifacts(noconfirm=False, force_push_tag=False):
+    assert 'AWS_SECRET_ACCESS_KEY' in __xonsh__.env
+
+    tree @(ARTIFACTS)
+
+    not noconfirm and confirm(
+        f'Would you like to release {ARTIFACTS} as {VERSION}? Type "I want to release this" to confirm\n',
+        'I want to release this'
+    )
+
+    print('[+] Upload to cache')
+    with open(DRVS_TXT) as fh:
+        upload_drv_paths_and_outputs([x.strip() for x in fh.readlines() if x])
+
+
+    print('[+] Upload to release bucket')
+    aws s3 cp --recursive @(ARTIFACTS)/ @(RELEASES_BUCKET)/
+
+    print('[+] git push tag')
+    git push @(['-f'] if force_push_tag else []) @(REPO) f'{VERSION}:refs/tags/{VERSION}'
+
+
+def do_tag_merge(force_tag=False, no_check_git=False):
+    if not no_check_git:
+        git_preconditions()
+    prev_branch = official_release_commit_tag(force_tag=force_tag)
+    merge_to_release(prev_branch)
+    git switch --detach @(VERSION)
+
+
+def build_artifacts(no_check_git=False):
+    if not no_check_git:
+        verify_are_on_tag()
+        git_preconditions()
+
+    print('[+] Evaluating')
+    eval_result = eval_jobs()
+    drv_paths = [x['drvPath'] for x in eval_result]
+
+    print('[+] Building')
+    realise(drv_paths)
+
+    with open(DRVS_TXT, 'w') as fh:
+        fh.write('\n'.join(drv_paths))
+
+    make_artifacts_dir(eval_result, ARTIFACTS)
+    print(f'[+] Done! See {ARTIFACTS}')
diff --git a/releng/environment.py b/releng/environment.py
new file mode 100644
index 000000000..643eb69d9
--- /dev/null
+++ b/releng/environment.py
@@ -0,0 +1,50 @@
+import dataclasses
+import urllib.parse
+
+S3_HOST = 's3.lix.systems'
+S3_ENDPOINT = 'https://s3.lix.systems'
+
+DEFAULT_STORE_URI_BITS = {
+    'region': 'garage',
+    'endpoint': 's3.lix.systems',
+    'want-mass-query': 'true',
+    'write-nar-listing': 'true',
+    'ls-compression': 'zstd',
+    'narinfo-compression': 'zstd',
+    'compression': 'zstd',
+    'parallel-compression': 'true',
+}
+
+
+@dataclasses.dataclass
+class RelengEnvironment:
+    name: str
+
+    aws_profile: str
+    cache_store_overlay: dict[str, str]
+    cache_bucket: str
+    releases_bucket: str
+    git_repo: str
+
+    def cache_store_uri(self):
+        qs = DEFAULT_STORE_URI_BITS.copy()
+        qs.update(self.cache_store_overlay)
+        return self.cache_bucket + "?" + urllib.parse.urlencode(qs)
+
+STAGING = RelengEnvironment(
+    name='staging',
+    aws_profile='garage_staging',
+    cache_bucket='s3://staging-cache',
+    cache_store_overlay={
+        'secret-key': 'staging.key'
+    },
+    releases_bucket='s3://staging-releases',
+    git_repo='ssh://git@git.lix.systems/lix-project/lix-releng-staging',
+)
+
+
+@dataclasses.dataclass
+class S3Credentials:
+    name: str
+    id: str
+    secret_key: str
diff --git a/releng/keys.py b/releng/keys.py
new file mode 100644
index 000000000..01607e1bf
--- /dev/null
+++ b/releng/keys.py
@@ -0,0 +1,18 @@
+import subprocess
+import json
+from . import environment
+
+
+def get_ephemeral_key(
+        env: environment.RelengEnvironment) -> environment.S3Credentials:
+    output = subprocess.check_output([
+        'ssh', '-l', 'root', environment.S3_HOST, 'garage-ephemeral-key',
+        'new', '--name', f'releng-{env.name}', '--read', '--write',
+        '--age-secs', '3600',
+        env.releases_bucket.removeprefix('s3://'),
+        env.cache_bucket.removeprefix('s3://')
+    ])
+    d = json.loads(output.decode())
+    return environment.S3Credentials(name=d['name'],
+                                     id=d['id'],
+                                     secret_key=d['secret_key'])
diff --git a/releng/release-jobs.nix b/releng/release-jobs.nix
new file mode 100644
index 000000000..e693a3a81
--- /dev/null
+++ b/releng/release-jobs.nix
@@ -0,0 +1,57 @@
+{ hydraJobs, pkgs }:
+let
+  inherit (pkgs) lib;
+  lix = hydraJobs.build.x86_64-linux;
+
+  systems = [ "x86_64-linux" ];
+  dockerSystems = [ "x86_64-linux" ];
+
+  doTarball =
+    {
+      target,
+      targetName,
+      rename ? null,
+    }:
+    ''
+      echo "doing: ${target}"
+      # expand wildcard
+      filename=$(echo ${target}/${targetName})
+      basename="$(basename $filename)"
+
+      echo $filename $basename
+      cp -v "$filename" "$out"
+      ${lib.optionalString (rename != null) ''
+        mv "$out/$basename" "$out/${rename}"
+        basename="${rename}"
+      ''}
+      sha256sum --binary $filename | cut -f1 -d' ' > $out/$basename.sha256
+    '';
+
+  targets =
+    builtins.map (system: {
+      target = hydraJobs.binaryTarball.${system};
+      targetName = "*.tar.xz";
+    }) systems
+    ++ builtins.map (system: {
+      target = hydraJobs.dockerImage.${system};
+      targetName = "image.tar.gz";
+      rename = "lix-${lix.version}-docker-image-${system}.tar.gz";
+    }) dockerSystems;
+
+  manualTar = pkgs.runCommand "lix-manual-tarball" { } ''
+    mkdir -p $out
+    cp -r ${lix.doc}/share/doc/nix/manual lix-${lix.version}-manual
+    tar -cvzf "$out/lix-${lix.version}-manual.tar.gz" lix-${lix.version}-manual
+  '';
+
+  tarballs = pkgs.runCommand "lix-release-tarballs" { } ''
+    mkdir -p $out
+    ${lib.concatMapStringsSep "\n" doTarball targets}
+    cp ${manualTar}/*.tar.gz $out
+    cp -r ${lix.doc}/share/doc/nix/manual $out
+  '';
+in
+{
+  inherit (hydraJobs) build;
+  inherit tarballs;
+}
diff --git a/releng/version.py b/releng/version.py
new file mode 100644
index 000000000..47ef23504
--- /dev/null
+++ b/releng/version.py
@@ -0,0 +1,6 @@
+import json
+
+version_json = json.load(open('version.json'))
+VERSION = version_json['version']
+MAJOR = '.'.join(VERSION.split('.')[:2])
+RELEASE_NAME = version_json['release_name']