World C2: Container Pipelines

Multi-arch builds in CI

You will learn: to build one image for both Intel and Arm computers.

Checked with GitHub Actions 2026-10 on 31 Oct 2026

The problem

Your image runs on the shop’s Intel server. On a new Arm server it stops at once: exec format error. Why?

Watch

Tap the line that asks for two CPU types.

0 of 1 found

A is one name with a pack for each CPU. Each computer pulls the pack that fits it.

Try it

Press Run. The arm64 pack fails on this Intel runner. Pick a fix for the yellow line.

The line is red. Fix the yellow lines, then run again.

What happened on GitHub

Push to main

Workflow file .github/workflows/image.yml

1name: Image
2on:
3  push:
4    branches: [main]
5permissions:
6  contents: read
7jobs:
8  image:
9    runs-on: ubuntu-latest
10    steps:
11      - uses: docker/setup-buildx-action@v4
12      - uses: docker/build-push-action@v7
13        with:
14          tags: kedai-kancil:ci
15          platforms: linux/amd64,linux/arm64

Yellow: lines 11–11. You can change these.

Pick a fixAdd QEMU before BuildxAdd Node before BuildxAdd checkout before Buildx

The line

Push to main · main

Predict

is that adapter: the Intel worker cooks for the Arm stove. What is the catch?

Check

Which pack does each computer pull?

Drag a card into a box. Or tap the card, then tap the box.

You did it!

You can now build one image for Intel and Arm computers.

Go deeper (optional)

GitHub also has Arm runners, like ubuntu-24.04-arm. They build arm64 natively, with no QEMU, so they are faster. docker buildx imagetools inspect <image> lists the packs inside one name.

Real rep (optional), in a public practice repo:

Real mission

Add docker/setup-qemu-action before setup-buildx-action.
Add platforms: linux/amd64,linux/arm64 to the build step.
Push the image, then list its packs.
docker buildx imagetools inspect ghcr.io/YOUR-NAME/YOUR-REPO:main

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