Building and uploading scikit-image wheels

We automate wheel building using this custom github repository that builds on the Travis-CI Linux and macOS machines, and the Appveyor VMs.

The Travis-CI interface for the builds is https://travis-ci.org/scikit-image/scikit-image-wheels

Appveyor interface at https://ci.appveyor.com/project/scikit-image/scikit-image-wheels

The driving Github repository is https://github.com/scikit-image/scikit-image-wheels

Using the repository

The repository contains the branches:

• master - for development and daily builds;
• vx.y.z - for building releases.

Travis-CI and Appveyor builds the master regularly (daily/weekly), via Travis-CI cron jobs and Appveyor scheduled builds <https://www.appveyor.com/docs/build-configuration/#scheduled-builds>.

Builds from the master branch upload to a Rackspace container for pre-releases at http://nightly-wheels.skimage.org

Builds from the release branches upload to a Rackspace container for releases at https://3f23b170c54c2533c070-1c8a9b3114517dc5fe17b7c3f8c63a43.ssl.cf2.rackcdn.com

Pull requests should usually be submitted to the master branch.

How it works

The wheel-building repository:

• does a fresh build of any required C / C++ libraries;
• builds a scikit-image wheel, linking against these fresh builds;
• processes the wheel using delocate (OSX) or auditwheel repair (Manylinux1). delocate and auditwheel copy the required dynamic libraries into the wheel and relinks the extension modules against the copied libraries;
• uploads the built wheels to a Rackspace container - see "Using the repository" above. The containers were kindly donated by Rackspace to scikit-learn).

The resulting wheels are therefore self-contained and do not need any external dynamic libraries apart from those provided as standard by OSX / Linux as defined by the manylinux1 standard.

The .travis.yml file in this repository has a line containing the API key for the Rackspace container encrypted with an RSA key that is unique to the repository - see https://docs.travis-ci.com/user/encryption-keys. This encrypted key gives the travis build permission to upload to the Rackspace containers we use to house the uploads.

Triggering a build

You will likely want to edit the .travis.yml and appveyor.yml files to specify the BUILD_COMMIT before triggering a build - see below.

You will need write permission to the Github repository to trigger new builds on the Travis-CI interface. Contact us on the mailing list if you need this.

You can trigger a build by:

• making a commit to the scikit-image-wheels repository (e.g. with git commit --allow-empty); or
• clicking on the circular arrow icon towards the top right of the Travis-CI page, to rerun the previous build.

In general, it is better to trigger a build with a commit, because this makes a new set of build products and logs, keeping the old ones for reference. Keeping the old build logs helps us keep track of previous problems and successful builds.

Which scikit-image commit does the repository build?

The scikit-image-wheels repository will build the commit specified in the BUILD_COMMIT at the top of the .travis.yml and appveyor.yml files. This can be any naming of a commit, including branch name, tag name or commit hash.

Uploading the built wheels to PyPI

• pre-releases container visible at http://nightly-wheels.skimage.org (https://7933911d6844c6c53a7d-47bd50c35cd79bd838daf386af554a83.ssl.cf2.rackcdn.com)
• release container visible at https://3f23b170c54c2533c070-1c8a9b3114517dc5fe17b7c3f8c63a43.ssl.cf2.rackcdn.com

Be careful, these links point to containers on a distributed content delivery network. It can take up to 15 minutes for the new wheel file to get updated into the containers at the links above.

When the wheels are updated, you can download them to your machine manually, and then upload them manually to PyPI, or by using twine. You can also use a script for doing this, housed at : https://github.com/MacPython/terryfy/blob/master/wheel-uploader

For the wheel-uploader script, you'll need twine and Beautiful Soup 4.

You will typically have a directory on your machine where you store wheels, called a wheelhouse. The typical call for wheel-uploader would then be something like:

VERSION=0.14.0
CDN_URL=https://3f23b170c54c2533c070-1c8a9b3114517dc5fe17b7c3f8c63a43.ssl.cf2.rackcdn.com
wheel-uploader -u $CDN_URL -s -v -w ~/wheelhouse -t all scikit_image $VERSION

where:

• -u gives the URL from which to fetch the wheels, here the https address, for some extra security;
• -s causes twine to sign the wheels with your GPG key;
• -v means give verbose messages;
• -w ~/wheelhouse means download the wheels from to the local directory ~/wheelhouse.

scikit_image is the root name of the wheel(s) to download / upload, and $VERSION contains the version to download / upload.

In order to upload the wheels, you will need something like this in your ~/.pypirc file:

[distutils]
index-servers =
    pypi

[pypi]
username:your_user_name
password:your_password

So, in this case, wheel-uploader will download all wheels starting with scikit-image-0.14.0- from the URL in $CDN_URL above to ~/wheelhouse, then upload them to PyPI.

Of course, you will need permissions to upload to PyPI, for this to work.