How to “Go run” without Go with Docker

I had this quite trivial problem: the version of Go I installed on my pc was quite old.

I started learning Go in February 2020 because the CTO of a client firm was thinking of using it to rebuild the app with a language other than PHP. He changed his mind after understanding Go has pointers.

Months later, though, I picked it up again… only to find out that my Go was a couple of versions behind.

Luckily I also started using Docker, in the meantime, so I don’t actually need to install anything unless I really, really need to.

So how to run Go without installing Go?

Let’s create a main.go file:

package main

import "fmt"

func main() {
    fmt.Println("Hello World!")
}

To run this file:

docker run --rm -v $PWD:/app golang sh -c "go run /app/main.go"

What’s going on here?

• --rm option removes the container after we use it;
• -v creates a volume from the current directory to /app;
• golang will pull the latest golang image from Docker Hub;
• sh runs the shell;
• with the -c option, sh will run the command in the following string "go run /app/main.go".

The result:

$ docker run --rm -v $PWD:/app golang sh -c "go run /app/main.go"
 Hello World!

What about docker-compose?

Let’s say we have a docker-compose.yml because we are developing some cool app:

version: '3'
services:
    app:
        image: golang

In a similar fashion as before…:

$ docker-compose run --rm -v $PWD:/app app sh -c "go run /app/main.go"
Creating go-demo_app_run … done
 Hello World!

We can of course specify a volume inside the YAML:

version: '3'
services:
    app:
        image: golang
        volumes: 
            - .:/app

and get rid of the -v option:

$ docker-compose run --rm app sh -c "go run /app/main.go"
 Creating go-demo_app_run … done
 Hello World!

One last note

Why the beer as featured image? In a previous version of this article I explained that the CTO decided not to go with Go while we were at a brewery. I later decided that I don’t like when people add too much useless personal info on top of their post, removed the explanation, but kept the beer…