/minimal-docker-container-for-golang

Primary LanguageGo

Minimal Docker Container for GoLang

The image starts from scratch: a special docker image that’s empty. It’s truly 0B!

A normal compiled app is dynamically linked to the libraries it needs to run (i.e., all the C libraries it binds to).

Unfortunately, scratch is empty, so there are no libraries and no loadpath for it to look in. What we have to do is modify our build script to statically compile our app with all libraries built in.

Build and Run an Hello World app

First Way

Build on your machine

0. Prerequisites

1. Build go executable for linux

CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -a -installsuffix cgo -o main .

Alternatively you can use the -s and -w linker flags to strip the debugging information and reduce container size

CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -ldflags="-s -w" -a -installsuffix cgo -o main .

2. Build Docker image

docker build -t go-docker-minimal .

3. Run Docker container

docker run -t go-docker-minimal

Second Way

Using a multi-stage build you can compile go executable and then create the minimal docker-image using the same dockerfile.

0. Prerequisites

1. Build

(With -f I can pass a non default dockerfile filename)

docker build -t go-docker-minimal-multistage -f Dockerfile.multistage .

2. Run

docker run -t go-docker-minimal-multistage

How much minimal?

The docker image created is less than 2 Mb. Running docker images you can see this:

REPOSITORY                        TAG                  IMAGE ID            CREATED             SIZE
go-docker-minimal                 latest               a5ad46a94d25        5 minutes ago       1.23MB

Credits

To have more information about it read this article from codeship.com