Utilities for building on Travis CI and AppVeyor

A set of scripts to automate builds of macOS and Manylinux1 wheels on the Travis CI infrastructure, and also Windows wheels on the AppVeyor infrastructure.

The Travis CI scripts are designed to build and test:

• Dual 32/64-bit architecture macOS wheels built for macOS 10.6+;
• 64-bit macOS wheels built for macOS 10.9+;
• 64-bit manylinuxX_x86_64 wheels, both narrow and wide Unicode builds, where X is any valid Manylinux version, such as 1, or 2010.
• 32-bit manylinuxX_i686 wheels, both narrow and wide Unicode builds.

You can currently build and test against Pythons 2.7, 3.5, 3.6, 3.7.

The small innovation here is that you can test against 32-bit builds, and both wide and narrow Unicode Python 2 builds, which was not easy on the default Travis CI configurations.

The AppVeyor setup is designed to build and test:

• 64-bit Windows win_amd64 wheels;
• 32-bit Windows win32 wheels.

You can currently build and test against Pythons 2.7, 3.5, 3.6, 3.7.

How does it work?

Multibuild is a series of bash scripts that define bash functions to build and test wheels.

Configuration is by overriding the default build function, and defining a test function.

The bash scripts are layered, in the sense that they loaded in the following sequence:

macOS

See multibuild/travis_osx_steps.sh.

For build and test phases, these bash scripts get sourced one after the other, so that functions and variables defined in later scripts can overwrite functions and variables in earlier scripts:

• multibuild/common_utils.sh
• multibuild/osx_utils.sh
• env_vars.sh
• multibuild/configure_build.sh
• multibuild/library_builders.sh
• config.sh

See travis_osx_steps.sh to review source order.

The macOS build / test phases run on the macOS VM started by Travis CI. Therefore any environment variable defined in the .travis.yml or bash shell scripts listed above are available for your build and test.

macOS builds may be targeted either at macOS 10.6+ (dual arch 64 / 32 bit) or macOS 10.9+ (64b only). These depend on the corresponding build of python from https://www.python.org/downloads/mac-osx/. At the time of writing, 10.9+ / 64 bit builds are supported for Python versions 3.6.5 / 2.7.15 and above. If you want to build for an older version of Python, you'll have to target 10.6+ / dual arch.

The build_wheel function builds the wheel, and the install_run function installs the wheel and tests it. Look in common_utils.sh for default definitions of these functions. See below for more details.

Manylinux

The build phase is in a Manylinux Docker container, but the test phase is in a clean Ubuntu 14.04 container.

Build phase

Specify the Manylinux version to build for with the MB_ML_VER environment variable. The default version is 1. Versions that are currently valid are:

• 1 (see [PEP 513](https://www.python.org/dev/peps/pep-0513);
• 2010 (see [PEP 571](https://www.python.org/dev/peps/pep-0571).

At some point 2014 will be a valid version - see [PEP 599](https://www.python.org/dev/peps/pep-0599).

The environment variable specified which Manylinux docker container you are building in.

The PLAT environment variable can be one of x86_64 or i686, specifying 64-bit and 32-bit builds, respectively. The default is 64-bit.

At the time of writing, Manylinux2010 only supports 64-bit builds, so MB_ML_VER=2010 and PLAT=i686 is an invalid combination, and will generate an error when trying to find the matching Docker image.

multibuild/travis_linux_steps.sh defines the build_wheel function, which starts up the Manylinux1 Docker container to run a wrapper script multibuild/docker_build_wrap.sh, that (within the container) sources the following bash scripts:

• multibuild/common_utils.sh
• multibuild/manylinux_utils.sh
• env_vars.sh
• multibuild/configure_build.sh
• multibuild/library_builders.sh
• config.sh

See docker_build_wrap.sh to review the order of script sourcing.

See the definition of build_multilinux in multibuild/travis_linux_steps.sh for the environment variables passed from Travis CI to the Manylinux1 container.

Once in the container, after sourcing the scripts above, the wrapper runs the real build_wheel function, which now comes (by default) from multibuild/common_utils.sh.

Test phase

Testing is in an Ubuntu 14.04 Docker container - see multibuild/docker_test_wrap.sh. multibuild/travis_linux_steps.sh defines the install_run function, which starts up the testing Docker container with a wrapper script multibuild/docker_test_wrap.sh. The wrapper script sources the following bash scripts:

• multibuild/common_utils.sh
• config.sh

See docker_test_wrap.sh for script source order.

See install_run in multibuild/travis_linux_steps.sh for the environment variables passed into the container.

It then (in the container) runs the real install_run command, which comes (by default) from multibuild/common_utils.sh.

Standard build and test functions

The standard build command is build_wheel. This is a bash function. By default the function that is run on macOS, and in the Manylinux container for the build phase, is defined in multibuild/common_utils.sh. You can override the default function in the project config.sh file (see below).

If you are building a wheel from pypi, rather than from a source repository, you can use the build_index_wheel command, again defined in multibuild/common_utils.sh.

Typically, you can get away with leaving the default build_wheel / build_index_wheel functions to do their thing, but you may need to define a pre_build function in config.sh. The default build_wheel and build_index_wheel functions will call the pre_build function, if defined, before building the wheel, so pre_build is a good place to build any required libraries.

The standard test command is the bash function install_run. The version run on macOS and in the Linux testing container is also defined in multibuild/common_utils.sh. Typically, you do not override this function, but you in that case you will need to define a run_tests function, to run your tests, returning a non-zero error code for failure. The default install_run implementation calls the run_tests function, which you will likely define in config.sh. See the examples below for examples of less and more complicated builds, where the complicated builds override more of the default implementations.

To use these scripts

• Make a repository for building wheels on Travis CI - e.g. https://github.com/MacPython/astropy-wheels - or in your case maybe https://github.com/your-org/your-project-wheels;

• Add this (here) repository as a submodule:

  git submodule add https://github.com/matthew-brett/multibuild.git

• Add your own project repository as another submodule:

  git submodule add https://github.com/your-org/your-project.git

• Create a .travis.yml file, something like this:

  env:
      global:
          - REPO_DIR=your-project
          # Commit from your-project that you want to build
          - BUILD_COMMIT=v0.1.0
          # pip dependencies to _build_ your project
          - BUILD_DEPENDS="Cython numpy"
          # pip dependencies to _test_ your project.  Include any dependencies
          # that you need, that are also specified in BUILD_DEPENDS, this will be
          # a separate install.
          - TEST_DEPENDS="numpy scipy pytest"
          - PLAT=x86_64
          - UNICODE_WIDTH=32
          - WHEELHOUSE_UPLOADER_USERNAME=travis-worker
          # Following generated with
          # travis encrypt -r your-org/your-project-wheels WHEELHOUSE_UPLOADER_SECRET=<the api key>
          # This is for Rackspace uploads.  Contact Matthew Brett, or the
          # scikit-learn team, for # permission (and the API key) to upload to
          # the Rackspace account used here, or use your own account.
          - secure:
              "MNKyBWOzu7JAUmC0Y+JhPKfytXxY/ADRmUIMEWZV977FLZPgYctqd+lqel2QIFgdHDO1CIdTSymOOFZckM9ICUXg9Ta+8oBjSvAVWO1ahDcToRM2DLq66fKg+NKimd2OfK7x597h/QmUSl4k8XyvyyXgl5jOiLg/EJxNE2r83IA="
  
  # You will likely prefer "language: generic" for travis configuration,
  # rather than, say "language: python". Multibuild doesn't use
  # Travis-provided Python but rather installs and uses its own, where the
  # Python version is set from the MB_PYTHON_VERSION variable. You can still
  # specify a language here if you need it for some unrelated logic and you
  # can't use Multibuild-provided Python or other software present on a
  # builder.
  language: generic
  
  # For CPython macOS builds only, the minimum supported macOS version and
  # architectures of any C extensions in the wheel are set with the variable
  # MB_PYTHON_OSX_VER: 10.9 (64-bit only) or 10.6 (64/32-bit dual arch).
  # All PyPy macOS builds are 64-bit only.
  
  # Required in Linux to invoke `docker` ourselves
  services: docker
  
  # Host distribution.  This is the distribution from which we run the build
  # and test containers, via docker.
  dist: xenial
  
  matrix:
    include:
      - os: linux
        env: MB_PYTHON_VERSION=2.7
      - os: linux
        env:
          - MB_PYTHON_VERSION=2.7
          - UNICODE_WIDTH=16
      - os: linux
        env:
          - MB_PYTHON_VERSION=2.7
          - PLAT=i686
      - os: linux
        env:
          - MB_PYTHON_VERSION=2.7
          - PLAT=i686
          - UNICODE_WIDTH=16
      - os: linux
        env:
          - MB_PYTHON_VERSION=3.5
      - os: linux
        env:
          - MB_PYTHON_VERSION=3.5
          - PLAT=i686
      - os: linux
        env:
          - MB_PYTHON_VERSION=3.6
      - os: linux
        env:
          - MB_PYTHON_VERSION=3.6
          - PLAT=i686
      - os: osx
        env:
          - MB_PYTHON_VERSION=2.7
      - os: osx
        env:
          - MB_PYTHON_VERSION=2.7
          - MB_PYTHON_OSX_VER=10.9
      - os: osx
        env:
          - MB_PYTHON_VERSION=3.5
      - os: osx
        env:
          - MB_PYTHON_VERSION=3.6
      - os: osx
        env:
          - MB_PYTHON_VERSION=3.7
          - MB_PYTHON_OSX_VER=10.9
      - os: osx
        language: generic
        env:
          - MB_PYTHON_VERSION=pypy-5.7
  
  before_install:
      - source multibuild/common_utils.sh
      - source multibuild/travis_steps.sh
      - before_install
  
  install:
      # Maybe get and clean and patch source
      - clean_code $REPO_DIR $BUILD_COMMIT
      - build_wheel $REPO_DIR $PLAT
  
  script:
      - install_run $PLAT
  
  after_success:
      # Upload wheels to Rackspace container
      - pip install wheelhouse-uploader
      # This uploads the wheels to a Rackspace container owned by the
      # scikit-learn team, available at http://wheels.scipy.org.  See above
      # for information on using this account or choosing another.
      - python -m wheelhouse_uploader upload --local-folder
          ${TRAVIS_BUILD_DIR}/wheelhouse/
          --no-update-index
          wheels

  The example above is for a project building from a Git submodule. If you aren't building from a submodule, but want to use pip to build from a source archive on https://pypi.org or similar, replace the first few lines of the .travis.yml file with something like:

  env:
      global:
          # Instead of REPO_DIR, BUILD_COMMIT
          - PROJECT_SPEC="tornado==4.1.1"

  then your install section could look something like this:

  install:
      - build_index_wheel $PROJECT_SPEC

• Next create a config.sh for your project, that fills in any steps you need to do before building the wheel (such as building required libraries). You also need this file to specify how to run your tests:

  # Define custom utilities
  # Test for macOS with [ -n "$IS_OSX" ]
  
  function pre_build {
      # Any stuff that you need to do before you start building the wheels
      # Runs in the root directory of this repository.
      :
  }
  
  function run_tests {
      # Runs tests on installed distribution from an empty directory
      python --version
      python -c 'import sys; import yourpackage; sys.exit(yourpackage.test())'
  }

  Optionally you can specify a different location for config.sh file with the $CONFIG_PATH environment variable.

• Optionally, create an env_vars.sh file to override the defaults for any environment variables used by configure_build.sh/library_builders.sh. In Linux, the environment variables used for the build cannot be set in the .travis.yml file, because the build processing runs in a Docker container, so the only environment variables that reach the container are those passed in via the docker run command, or those set in env_vars.sh.

  As for the config.sh file, you can specify a different location for the file by setting the $ENV_VARS_PATH environment variable. The path in $ENV_VARS_PATH is relative to the repository root directory. For example, if your repository had a subdirectory scripts with a file my_env_vars.sh, you should set ENV_VARS_PATH=scripts/my_env_vars.sh.

• Make sure your project is set up to build on Travis CI, and you should now be ready (to begin the long slow debugging process, probably).

• For the Windows wheels, create an appveyor.yml file, something like:

  • https://github.com/MacPython/numpy-wheels/blob/master/.appveyor.yml
  • https://github.com/MacPython/astropy-wheels/blob/master/appveyor.yml
  • https://github.com/MacPython/nipy-wheels/blob/master/appveyor.yml
  • https://github.com/MacPython/pytables-wheels/blob/master/appveyor.yml

  Note the Windows test customizations etc are inside appveyor.yml, and that config.sh and env_vars.sh are only for the Linux/Mac builds on Travis CI.

• Make sure your project is set up to build on AppVeyor, and you should now be ready (for what could be another round of slow debugging).

If your project depends on NumPy, you will want to build against the earliest NumPy that your project supports - see forward, backward NumPy compatibility. See the astropy-wheels Travis file for an example specifying NumPy build and test dependencies.

Here are some simple example projects:

• https://github.com/MacPython/astropy-wheels
• https://github.com/scikit-image/scikit-image-wheels
• https://github.com/MacPython/nipy-wheels
• https://github.com/MacPython/dipy-wheels

Less simple projects where there are some serious build dependencies, and / or macOS / Linux differences:

• https://github.com/MacPython/matplotlib-wheels
• https://github.com/python-pillow/Pillow-wheels
• https://github.com/MacPython/h5py-wheels

Multibuild development

The main multibuild repository is always at https://github.com/matthew-brett/multibuild

We try to keep the master branch stable and do testing and development in the devel branch. From time to time we merge devel into master.

In practice, you can check out the newest commit from devel that works for you, then stay at it until you need newer features.