lesson-8

Use containers to compile tools

So, your friend made a tool that you really like. He made it using a language you're not familiar with.

But you don't want to download and install all the dependencies it requires to compile.

For the sake of a realy example, let's pick a game I created a few days ago using Golang. It's 2048 game playable on command-line. Sounds fun, eh?

https://github.com/alyyousuf7/twenty48

Let's clone the repository and have a look at it's Dockerfile.

$ git clone https://github.com/alyyousuf7/twenty48.git
$ cd twenty48 && cat Dockerfile

Pretty small file, right? There's more to it.

I have made a Makefile which lets you,

• get inside a container pretty quickly using make shell
• and compile the Golang binary using make binary

$ make shell
root@<container id>:/go/src/github.com/alyyousuf7/twenty48# make binary
root@<container id>:/go/src/github.com/alyyousuf7/twenty48# exit
$ ./bin/twenty48

You just compiled your first Golang program without even install Golang on your machine! Isn't this cool?

Explanation

When you ran make shell, it executed the following Docker commands:

$ docker build -t twenty48:latest .
$ docker run -v $(pwd)/bin:/go/src/github.com/alyyousuf7/twenty48/bin twenty48:latest

It created a Docker image and ran it's container with a directory mounted to your host machine.

When you ran make binary inside the container, it ran the go build command and output the binary in bin directory inside the container.

Since the bin directory was mounted, the twenty48 binary was copied to your host machine as well.

In the next lesson, we'll learn how to connect multiple containers and communicate in private.