Bootstrapping infra.git

The infra.git repo uses python wheel files, virtualenv and pip to manage dependencies. The process for bootstrapping these is contained entirely within bootstrap/ directory.

See dockerbuild for a tool that tries to make a lot of this easier. If you use dockerbuild to build a wheel for bootstrap, you will need to upload it manually to the wheelhouse. (TODO: We should enable Dockerbuild to upload to wheelhouse too.) Check the .dockerbuild/wheels directory for the local wheel.

Note: The tooling outlined here supports building a python virtualenv for use only in the infra.git repo. vpython is a more distributed tool that accomplishes a similar thing, but is not described in this file. See here for its documentation.

TL;DR - Workflows

Setting up the env with already-built-deps

Just run:

gclient sync
# OR
gclient runhooks

Adding a new dep

Say we want to add a stock my_pkg python package at version 1.2.3:


If it comes from a tarball:

$ ./bootstrap/ <tarball>

Another repo

If it comes from a repo, file a ticket to have it mirrored (no matter what VCS!) to<repo_url>

Grab the git commit hash of the commit to build: badc0ffeebadc0ffeebadc0ffeebadc0

Then add the actual dep:

$ edit bootstrap/deps.pyl  # add a new entry (see the 'deps.pyl' section)
  'my_pkg' : {
    'version': '1.2.3',
    'build': 0,  # This is the first build
    'gs':  'deadbeefdeadbeefdeadbeefdeadbeef.tar.gz',  # if tarball
    'rev': 'badc0ffeebadc0ffeebadc0ffeebadc0',         # if repo

Then build it:

$ ./bootstrap/ --upload
# builds and uploads my_pkg-1.2.3-0_deadbeef...-....whl to google storage
If your dep is not pure-python, you will have to run for each platform.
If you‘re running an unsupported platform (the main symptom being that gclient sync fails with __main__.NoWheelException: No matching wheel found for. See for more details), then you have to run to rebuild the missing packages. See also ‘rolling deps’ below. If you don’t have permission to upload the generated packages to Cloud Storage (e.g. if you're not a Googler), then drop the --upload option and all packages will be stored locally only.

If your dep needs special treatment

Do everything in the Adding a new dep section, but before running, add a file custom_builds/{wheel package name}.py. This file is expected to implement:

def Build(source_path, wheelhouse_path)

See custom builds below for more detail. (a.k.a. “I just want a working infra repo!”)

Run gclient runhooks. Under the hood, this runs:

./bootstrap/ --deps_file bootstrap/deps.pyl ENV

This creates a virtualenv called {repo_root}/ENV with all the deps contained in bootstrap/deps.pyl. You must be online, or must already have the wheels for your system in cache.

If you already have an ENV directory, will check the manifest in ENV to see if it matches deps.pyl (i.e. the diff is zero). If it's not, then ENV directory will be re-created from scratch. will automatically use the environment ENV. It is an error to use without first setting up ENV.


This file is a python dictionary containing the exact versions of all Python module dependencies. These versions are the standard upstream package versions (e.g. ‘0.8.0’), plus the commit hash or sha1.{ext} of an ingested source bundle.

The format of this file is {'package_name': <values>}. This file is a Python ast literal, so comments are allowed and encouraged.

Note that the package_name key is the pip-reported name (the one set in It may be different from the name used for import, and for the wheel.

Values are:

  • version: The pip version of the module
  • build: An integer representing which build of this version/hash. If you modify the way that a requirement is built, but not the source hash, you can bump the build number to get a new pinned dependency.

And either:

  • rev: The revision or sha1 of the source for this module. The repo is git+{package_name}
  • gs: {sha1}.{ext} indicates file gs://chrome-python-wheelhouse/sources/{sha1}.{ext}. The sha1 will be checked against the content of the file.

And optionally:

  • implicit: A boolean indicating that this dep should only be installed as a dependency of some other dep. For example, you want package A, which depends on package Z, but you don't really care about Z. You should mark Z as implicit to allow it to be pinned correctly, but not to deliberately install it.

Some python modules don't have functional python repos (i.e. ones that pip can natively clone+build), and thus ship their source in tarballs. To ingest such a tarball into the infra google storage bucket, use /path/to/archive. This will print the value for the ‘gs’ key for a deps.pyl entry. / rolling deps

Any time a new dependency/version is introduced into deps.pyl, you must run --upload. If the dependency is a pure-Python dependency (i.e. no compiled extensions), you only need to run it once on CPython 2.7. You can tell that it's a pure python module by looking at the name of the wheel file. For example:


Is compatible with Python 2 and Python 3 (py2.py3) any python ABI (none), and any OS platform (any).

Running will only attempt to build dependencies which are missing for the current platform.

If the module does contain compiled extensions, you must run on the following systems (all with CPython 2.7):

  • OS X 10.9 - x86_64
  • Windows 7 - x86_64
  • Linux - x86_64

TODO(iannucci): Add job to build wheels on all appropriate systems.

Once a wheel is sucessfully built, it is uploaded to gs://chrome-python-wheelhouse/wheels if it is not there already.

Only Googlers have access to that bucket. Make sure to run the following command to authenticate first:

depot_tools/third_party/gsutil/gsutil config assumes that it can find gsutil on PATH, so go ahead and install it appropriately for whichever platform you're on.

Custom builds

Sometimes building a wheel is a bit trickier than pip wheel {repo}@{hash}. In order to support this, add a script named custom_builds/{name}.py. This module should have a function defined like:

def Build(source_path, wheelhouse_path)

Where source_path is a string path to the checked-out / unpacked source code, and wheelhouse_path is a string path where expects to find a .whl file after Build completes.

Note that your Build function will actually need to invoke pip manually. Currently you can get the path for pip by doing: os.path.join(sys.prefix, 'bin', 'pip'), and you can invoke it with subprocess (example).

Rolling the version of wheel

Since wheel is a package needed to build the wheels, it has a slightly different treatment. To roll a wheel, bump the version in deps.pyl, and then run to build and upload the wheel for wheel pinned at the version in deps.pyl.

Once you do that, will continue working as expected.

Building deps on Windows

TODO(iannucci): actually implement this

Windows builds require a slightly more care when building, due to the complexities of getting a compile environment. To this effect, relies on the depot_tools/win_toolchain functionality to get a hermetic windows compiler toolchain. This should not be an issue for chromium devs working on windows, since they should already have this installed by compiling chromium, but it's something to be aware of.

Modified (non-upstream) deps

If it is necessary to roll a patched version of a library, we should branch it in the infra googlesource mirror. This branch should be named {version}-cr, and will build packages whose version is {version}.{cr_version} (e.g. modify on this branch to add an additional component to the version field).

For example, given the package jane at version 2.1.3, we would create a branch 2.1.3-cr. On this branch we would commit any changes necessary to 2.1.3, and would adjust the version number in the builds to be e.g.

Platform Problems


A builder is failing with NoWheelException, but you feel strongly that the entry in deps.pyl matches what is in the wheelhouse.

One thing that might be happening is that pip doesn't think that wheel, based on its filename, is supported for that platform. You might log on to that bot and start a python interpreter:

>>> import pip
>>> pip.pep425tags.supported_tags

will list all of the supported tags for that platform. What to do next depends on your particular situation, but hopefully this information is helpful for giving you ideas.