melangeDockerImageWithApko

README

Melange and a Docker Image with Apko

https://dev.to/patrickdomnick/building-a-go-package-with-melange-and-a-docker-image-with-apko-141c

In this tutorial, we will learn how to create a Go package with Melange, build a Docker with Apko image, and showcase examples using GitLab CI.

Prerequisites

Before we begin, make sure you have the following tools installed on your system:

• Docker
• Golang
• Melange
• Apko

Using Golang version go version go1.23.0 linux/amd64 managed by gvm.

Melange install:

go install chainguard.dev/melange@latest

Apki install:

go install chainguard.dev/apko@latest

Keyfile generation

Before generate it's important include on .gitignore two entrances:

*.rsa
*.rsa.pub

We need to create a private and public key pair to sign our artifacts:

melange keygen

Creating a Go Package with Melange

Initialize a Go module:

go mod init gitlab.com/tarsoqueiroz/golang-apko-example

Create your Go source code files and write your package logic.

• File main.go: simple web server.

Create a melange.yaml file in the root of your package directory. This file will define the build configuration for your package.

Build your package locally with Melange:

melange build --signing-key melange.rsa --runner docker melange.yaml

This will generate an APKINDEX.json, APKINDEX.tar.gz and .apk file in your packages directory.

Building a Docker Image with apko.yaml

Create an apko.yaml file in the root of your package directory. This file will define the Docker image build configuration.

The important line is the golang-apko-example@local package signaling a local package should be used instead of the wolfi packages.

Build the Image with your local repository appended:

apko build --log-level debug --sbom-path ./sbom/ --repository-append $(pwd)/packages --keyring-append=melange.rsa.pub apko.yaml golang-apko-example:latest image.tar

This will build a Docker image as an image.tar with our local package and create SBOM files for our image.

To actually use the image locally we have to load and execute it:

docker load --input image.tar
docker run --rm --name apk -p 8910:8910 -d golang-apko-example:latest-amd64