SASS is a delightful way to write CSS, but compiling SASS for your web application might not be the most obvious task. There are different installation methods, most of them involving cluttering up your filesystem with external dependencies. Compiling SASS is easy when you’re doing rails or sinatra-work, but I demand to write code in a compiled language. So I created a docker image to compile SASS code automatically called larryprice/sass.

Running this image is easy. Let’s say I have some SASS code:

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.service-home .search-area {
  margin-top: 0;

  .service-name {
    font-size: 44px;
    font-weight: bold;
  }
}

Given that I have Docker already installed, I’ll start up my Docker container:

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$ docker run -v /home/larry/test-project/public/css:/src --rm larryprice/sass

That’s it. The directory /home/larry/test-project/public/css (containing my SASS code) is now being watched by the SASS compiler. Any time I make a change to a file in that directory, my code will automatically be recompiled. The above command runs the SASS watcher in the foreground, which allows me to see any compile errors in my terminal window. If I wanted to run the SASS compiler in the background, I just have to add the -d flag:

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$ docker run -v /home/larry/test-project/public/css:/src --rm -d larryprice/sass

If my project is using docker-compose, I could add an image in my docker-compose.yml to run the SASS compiler alongside my application. For instance, if I’m running a web application with go:

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app:
  image: golang:1.4
  working_dir: /go/src/simple-golang-app
  command: go run main.go
  volumes:
    - ./simple-golang-app:/go/src/simple-golang-app
sass:
  image: larryprice/sass
  volumes:
    - ./public/css:/src

Now, running docker-compose up would also run the SASS compiler.

I like using docker-compose in these situations as it limits the number of conflicting tools installed on my host machine. If I ever decide that SASS is the worst or that ruby is the devil, all I have to do is docker rmi larryprice/sass. No need to run find commands for every file with sass in the title; just a single, simple command to destroy all evidence.