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GitHub Action: Setup Alpine Linux

A GitHub Action to easily set up and use a chroot-based [1] Alpine Linux environment in your workflows and emulate any supported CPU architecture (using QEMU).

runs-on: ubuntu-latest
steps:
  - uses: jirutka/setup-alpine@v1
    with:
      branch: v3.15

  - run: cat /etc/alpine-release
    shell: alpine.sh {0}

See more examples…

Highlights

  • Easy to use and flexible

    • Add one step uses: jirutka/setup-alpine@v1 to set up the Alpine environment, for the next steps that should run in this environment, specify shell: alpine.sh {0}. See Usage examples for more.

    • You can switch between one, or even more, Alpine environments and the host system (Ubuntu) within a single job (i.e. each step can run in a different environment). This is ideal, for example, for cross-compilations.

  • Emulation of non-x86 architectures

    • This couldn’t be easier; just specify input parameter arch. The action sets up QEMU user space emulator and installs Alpine Linux environment for the specified architecture. You can then build and run binaries for/from this architecture, just like on real hardware, but (significantly) slower (it’s a software emulation after all).

  • No hassle with Docker images

    • You don’t have to write any Dockerfiles, for example, to cross-compile Rust crates with C dependencies.[2]

    • No, you really don’t need any so-called “official” Docker image for gcc, nodejs, python or whatever you need… just install it using apk from Alpine packages. It is fast, really fast!

  • Always up to date environment

    • The whole environment, all packages, are always installed directly from the Alpine Linux’s official repositories using apk-tools (Alpine’s package manager). There’s no intermediate layer that tends to lang behind with security fixes (such as Docker images). — You might be thinking, isn’t that slow? No, it’s faster than pulling a Docker image!

    • No, you really don’t need any Docker image to get a stable build environment. Alpine Linux provides stable releases (branches); these get just (security) fixes, no breaking changes.

  • It’s simple and lightweight

    • You don’t have to worry about that on a hosted CI service, but still… This action is written in ~220 LoC and uses only basic Unix tools (chroot, mount, wget, Bash, …) and apk-tools (Alpine’s package manager). That’s it.

Parameters

Inputs

apk-tools-url

URL of the apk-tools static binary to use. It must end with #!sha256! followed by a SHA-256 hash of the file. This should normally be left at the default value.

Default: see action.yml

arch

CPU architecture to emulate using QEMU user space emulator. Allowed values are: x86_64 (native), x86 (native), aarch64, armhf [3], armv7, ppc64le, riscv64 [4], and s390x.

Default: x86_64

branch

Alpine branch (aka release) to install: vMAJOR.MINOR, latest-stable, or edge.

Example: v3.15
Default: latest-stable

extra-keys

A list of paths of additional trusted keys (for installing packages from the extra-repositories) to copy into /etc/apk/keys/. The paths should be relative to the workspace directory (the default location of your repository when using the checkout action).

Example: .keys/[email protected]

extra-repositories

A list of additional Alpine repositories to add into /etc/apk/repositories (Alpine’s official main and community repositories are always added).

mirror-url

URL of an Alpine Linux mirror to fetch packages from.

packages

A list of Alpine packages to install.

Example: build-base openssh-client
Default: no extra packages

shell-name

Name of the script to run sh in the Alpine chroot that will be added to GITHUB_PATH. This name should be used in jobs.<job_id>.steps[*].shell (e.g. shell: alpine.sh {0}) to run the step’s script in the chroot.

Default: alpine.sh

volumes

A list of directories on the host system to mount bind into the chroot. You can specify the source and destination path: <src-dir>:<dest-dir>. The <src-dir> is an absolute path of existing directory on the host system, <dest-dir> is an absolute path in the chroot (it will be created if doesn’t exist). You can omit the latter if they’re the same.

Please note that /home/runner/work (where’s your workspace located) is always mounted, don’t specify it here.

Example: ${{ steps.alpine-aarch64.outputs.root-path }}:/mnt/alpine-aarch64

Outputs

root-path

Path to the created Alpine root directory.

Usage examples

Basic usage

runs-on: ubuntu-latest
steps:
  - uses: actions/checkout@v2

  - name: Setup latest Alpine Linux
    uses: jirutka/setup-alpine@v1

  - name: Run script inside Alpine chroot as root
    run: |
      cat /etc/alpine-release
      apk add nodejs npm
    shell: alpine.sh --root {0}

  - name: Run script inside Alpine chroot as the default user (unprivileged)
    run: |
      ls -la  # as you would expect, you're in your workspace directory
      npm build
    shell: alpine.sh {0}

  - name: Run script on the host system (Ubuntu)
    run: |
      cat /etc/os-release
    shell: bash

Set up Alpine with specified packages

- uses: jirutka/setup-alpine@v1
  with:
    branch: v3.15
    packages: >
      build-base
      libgit2-dev
      meson

Set up and use Alpine for a different CPU architecture

runs-on: ubuntu-latest
steps:
  - name: Setup Alpine Linux v3.15 for aarch64
    uses: jirutka/setup-alpine@v1
    with:
      arch: aarch64
      branch: v3.15

  - name: Run script inside Alpine chroot with aarch64 emulation
    run: uname -m
    shell: alpine.sh {0}

Set up Alpine with packages from the testing repository

- uses: jirutka/setup-alpine@v1
  with:
    extra-repositories: |
      http://dl-cdn.alpinelinux.org/alpine/edge/testing
    packages: some-pkg-from-testing

Set up and use multiple Alpine environments in a single job

runs-on: ubuntu-latest
steps:
  - name: Setup latest Alpine Linux for x86_64
    uses: jirutka/setup-alpine@v1
    with:
      shell-name: alpine-x86_64.sh

  - name: Setup latest Alpine Linux for aarch64
    uses: jirutka/setup-alpine@v1
    with:
      arch: aarch64
      shell-name: alpine-aarch64.sh

  - name: Run script inside Alpine chroot
    run: uname -m
    shell: alpine-x86_64.sh {0}

  - name: Run script inside Alpine chroot with aarch64 emulation
    run: uname -m
    shell: alpine-aarch64.sh {0}

  - name: Run script on the host system (Ubuntu)
    run: cat /etc/os-release
    shell: bash

Cross-compile Rust application with system libraries

runs-on: ubuntu-latest
strategy:
  matrix:
    include:
      - rust-target: aarch64-unknown-linux-musl
        os-arch: aarch64
env:
  CROSS_SYSROOT: /mnt/alpine-${{ matrix.os-arch }}
steps:
  - uses: actions/checkout@v1

  - name: Set up Alpine Linux for ${{ matrix.os-arch }} (target arch)
    id: alpine-target
    uses: jirutka/setup-alpine@v1
    with:
      arch: ${{ matrix.os-arch }}
      branch: edge
      packages: >
        dbus-dev
        dbus-static
      shell-name: alpine-target.sh

  - name: Set up Alpine Linux for x86_64 (build arch)
    uses: jirutka/setup-alpine@v1
    with:
      arch: x86_64
      packages: >
        build-base
        pkgconf
        lld
        rustup
      volumes: ${{ steps.alpine-target.outputs.root-path }}:${{ env.CROSS_SYSROOT }}
      shell-name: alpine.sh

  - name: Install Rust stable toolchain via rustup
    run: rustup-init --target ${{ matrix.rust-target }} --default-toolchain stable --profile minimal -y
    shell: alpine.sh {0}

  - name: Build statically linked binary
    env:
      CARGO_BUILD_TARGET: ${{ matrix.rust-target }}
      CARGO_PROFILE_RELEASE_STRIP: symbols
      PKG_CONFIG_ALL_STATIC: '1'
      PKG_CONFIG_LIBDIR: ${{ env.CROSS_SYSROOT }}/usr/lib/pkgconfig
      RUSTFLAGS: -C linker=/usr/bin/ld.lld
      SYSROOT: /dummy  # workaround for https://github.com/rust-lang/pkg-config-rs/issues/102
    run: |
      # Workaround for https://github.com/rust-lang/pkg-config-rs/issues/102.
      echo -e '#!/bin/sh\nPKG_CONFIG_SYSROOT_DIR=${{ env.CROSS_SYSROOT }} exec pkgconf "$@"' \
          | install -m755 /dev/stdin pkg-config
      export PKG_CONFIG="$(pwd)/pkg-config"
      cargo build --release --locked --verbose
    shell: alpine.sh {0}

  - name: Try to run the binary
    run: ./myapp --version
    working-directory: target/${{ matrix.rust-target }}/release
    shell: alpine-target.sh {0}

History

This action is an evolution of the alpine-chroot-install script I originally wrote for Travis CI in 2016. The implementation is principally the same, but tailored to GitHub Actions. It’s so simple and fast thanks to how awesome apk-tools is!

License

This project is licensed under MIT License. For the full text of the license, see the LICENSE file.

1. If you don’t know what chroot is, think of it as a very simple container. It’s one of the cornerstones of containers and the only one that is actually needed for this use case.
2. The popular cross tool used by actions-rs/cargo action doesn’t allow you to easily install additional packages or whatever needed for building your crate without creating, build and maintaining custom Docker images (cross-rs/cross#281). This just impose unnecessary complexity and boilerplate.
3. armhf is armv6 with hard-float.
4. riscv64 is available since v3.20.