Minimize GO Resource Size With Docker Multi-Stage Build

Lately, I’ve been exploring Golang. Given my Backend experience is largely in NodeJS, I anticipated a sharp learning curve. But so far, there hasn’t been as much hair pulling as I expected. GO walks a good balance between enforcing strict patterns, rules, and types while maintaining syntax conciseness and code efficiency.

Since GO is a compiled language and runs as an executable, we can take advantage of a feature from Docker 17, multi-stage build. This feature allows developers to use one base image as the builder and a more efficient or smaller one as the final resource’s image. Essentially, multi-stage lets you use the artifact from one stage in another stage.

The main benefit of this is a smaller image to deploy. It could also enable a shorter build time in the development lifecycle too because you can choose the minimal resource required.

Let’s see how:

In my example, I will create one Dockefile that contains most of the configuration and two docker-compose files to illustrate how to support multiple build environments, which any real-world service should have.

Docker Compose

Supporting multiple deployment environments is a pretty typical real-world requirement. Of course, you don’t see docker-compose to do this. But I’ve always preferred docker-compose for a more streamlined setup and less of a need to string up variables in docker build commands.

For my example, I created two docker-compose files with the key difference being the environment variable, ENV. This variable can be used to define which environment file the GO program will use.

For development:

docker-compose-dev.yml

version: '3.5'
services:
  go-server:
    build:
      args:
        - ENV=dev
      context: .
    image: go-server-dev
    container_name: go-server-box-dev
    ports:
      - "9000:9000"

For production:

docker-compose.yml

version: '3.5'
services:
  go-server:
    build:
      args:
        - ENV=prod
      context: .
    image: go-server
    container_name: go-server-box
    ports:
      - "4445:9000"