PiShrink GitHub Action

GitHub action to shrink & compress a Raspberry Pi SD card image using PiShrink.

This action is the inverse of ethanjli/pigrow-action.

Basic Usage Examples

Note: in the below example sequences of GitHub Actions job steps, the URL of the downloaded image doesn't actually exist! Normally, you would generate an image file by some other method, e.g. downloading a base image, expanding it, and modifying its filesystem (e.g. with Pimod, as in a below example).

Shrink with gzip

- name: Download an example image
  run: wget http://some-website.com/large-rpi-sd-card-image.img

- name: Shrink image
  uses: ethanjli/pishrink-action@v0.1.2
  with:
    image: large-rpi-sd-card-image.img
    compress: gzip
    compress-parallel: true

- name: Upload image to Job Artifacts
  uses: actions/upload-artifact@v4
  with:
    name: shrunken-image
    path: large-rpi-sd-card-image.img
    if-no-files-found: error
    compression-level: 0
    overwrite: true

Shrink with xz

- name: Download an example image
  run: wget http://some-website.com/large-rpi-sd-card-image.img

- name: Shrink image
  uses: ethanjli/pishrink-action@v0.1.2
  with:
    image: large-rpi-sd-card-image.img
    compress: xz
    compress-parallel: true

- name: Upload image to Job Artifacts
  uses: actions/upload-artifact@v4
  with:
    name: shrunken-image
    path: large-rpi-sd-card-image.img
    if-no-files-found: error
    compression-level: 0
    overwrite: true

Separate destination

- name: Download an example image
  run: wget http://some-website.com/large-rpi-sd-card-image.img

- name: Shrink image
  uses: ethanjli/pishrink-action@v0.1.2
  with:
    image: large-rpi-sd-card-image.img
    destination: result.img.gz
    compress: gzip
    compress-parallel: true

- name: Upload image to Job Artifacts
  uses: actions/upload-artifact@v4
  with:
    name: shrunken-image
    path: result.img.gz
    if-no-files-found: error
    compression-level: 0
    overwrite: true

Automatically-determined destination

- name: Download an example image
  run: wget http://some-website.com/large-rpi-sd-card-image.img

- name: Shrink image
  id: shrink-image
  uses: ethanjli/pishrink-action@v0.1.2
  with:
    image: large-rpi-sd-card-image.img
    compress: gzip
    compress-parallel: true

- name: Upload image to Job Artifacts
  uses: actions/upload-artifact@v4
  with:
    name: shrunken-image
    path: ${{ steps.shrink-image.outputs.destination }} # this is large-rpi-sd-card-image.img.gz
    if-no-files-found: error
    compression-level: 0
    overwrite: true

Pimod Usage Example

This example job uses Pimod to generate a custom image, and then shrinks it before uploading as an artifact on the GitHub Actions job:

jobs:
  build:
    name: Build image
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v4

      - name: Make a Pifile for Pimod
        uses: 1arp/create-a-file-action@0.4.5
        with:
          file: cowsay.Pifile
          content: |
            FROM https://downloads.raspberrypi.com/raspios_lite_arm64/images/raspios_lite_arm64-2024-03-15/2024-03-15-raspios-bookworm-arm64-lite.img.xz
            TO cowsay-image.img
            PUMP 8G

            # Install and test out cowsay:
            RUN apt-get update
            RUN apt-get install -y cowsay
            RUN /usr/games/cowsay "I'm running in a chroot!"

      - name: Build the image
        uses: Nature40/pimod@master
        with:
          pifile: cowsay.Pifile

      - name: Shrink the image
        uses: ethanjli/pishrink-action@v0.1.2
        with:
          image: cowsay-image.img
          compress: gzip
          compress-parallel: true

      - name: Upload image to Job Artifacts
        uses: actions/upload-artifact@v4
        with:
          name: rpi-cowsay-arm64-latest
          path: cowsay-image.img.gz
          if-no-files-found: error
          retention-days: 0
          compression-level: 0
          overwrite: true

PiNspawn Usage Example

This example job uses ethanjli/pinspawn-action to generate a custom image, and then shrinks it before uploading as an artifact on the GitHub Actions job:

jobs:
  build:
    name: Build image
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v4

      - name: Download a base image
        run: wget https://downloads.raspberrypi.com/raspios_lite_arm64/images/raspios_lite_arm64-2024-03-15/2024-03-15-raspios-bookworm-arm64-lite.img.xz

      - name: Grow the image
        uses: ethanjli/pigrow-action@v0.1.1
        with:
          image: 2024-03-15-raspios-bookworm-arm64-lite.img.xz
          destination: cowsay-image.img
          mode: to
          size: 8G

      - name: Build the image
        uses: ethanjli/pinspawn-action@v0.1.1
        with:
          image: cowsay-image.img
          run: |
            apt-get update
            apt-get install -y cowsay
            /usr/games/cowsay 'I am running in a light-weight namespace container!'

      - name: Shrink the image
        uses: ethanjli/pishrink-action@v0.1.1
        with:
          image: cowsay-image.img
          compress: gzip
          compress-parallel: true

      - name: Upload the image to Job Artifacts
        uses: actions/upload-artifact@v4
        with:
          name: rpi-cowsay-arm64-latest
          path: cowsay-image.img.gz
          if-no-files-found: error
          retention-days: 0
          compression-level: 0
          overwrite: true

You can also replace ethanjli/pinspawn-action@v0.1.1 with ethanjli/piqemu-action@v0.1.0 to run commands in a booted QEMU VM, if you need to run commands which interact with the Docker daemon in your custom image.

Usage Options

Inputs:

Input	Allowed values	Required?	Description
image	file path	yes	Path of the image to shrink.
destination	file path	no	Path to write the shrunken image to.
compress	gzip, xz, none	no (default none)	Compress the image after shrinking it.
compress-parallel	true, false	no (default false)	Compress the image in parallel using multiple cores.
prevent-expansion	true, false	no (default false)	Prevent automatic filesystem expansion when the image is booted for the first time.
advanced-fs-repair	true, false	no (default false)	Attempt to repair the filesystem using additional options if the normal repair fails.
verbose	true, false	no (default false)	Enable more verbose output

Outputs:

• destination is the path of the shrunken image produced by pishrink. If it was compressed with gzip or xz, this path will include .gz or .xz (respectively) as its file extension.

Credits

This repository uses the pishrink.sh script provided by Drewsif/PiShrink, published under the MIT License; this repository is also released under the MIT License.