ASCII Sprites with Golang

I’ve been trying to think of a way to spruce up the Docker container which we print on all of the t-shirts for Dockercon. At Dockercon 16 in Seattle we told everyone to run this command:

$ docker run -it --rm hello-seattle

That displays some data about how containers work from a really superficial level. Somewhat useful for novices, I guess, but it doesn’t exactly have a ton of pizzazz.

When I first started working at Docker a year and half ago, I converted some of my ancient Pyweek video games which I’ve written to run from Docker containers. These tend to be a lot more interesting, but getting them running from the command line can be a huge pain in the neck. You have to pass in the X11 socket, give it access to the sound card and do all sorts of nastiness which I wouldn’t want to print on the back of a t-shirt. This would be fine if the docker engine had support for showing graphical style applications, but for now, I’ve ruled it out for a quick and dirty demo.

Instead, I’ve been thinking about the limitations of ASCII and have been wondering if there were a way to use it with typical gaming primitives like sprites. I wanted to keep the size of the container image really small, so that ruled out writing anything in python where I’d have to package up the interpreter. Instead I went with a statically compiled golang application which meant it could live by itself inside of a container.

I’m not actually finished yet, but I managed to cobble together a bit of a demo. It just bounces around a bunch of ASCII Docker whales, but even that is a step up from the old container. Here’s a screenshot:

You can give it a try with this command:

$ docker run -it --rm pdevine/whale-test

Use ‘a’ to add more whales, and ‘z’ to take them away. ‘q’ will quit out of the program. Oh yeah, and I guess it goes without saying that you need Docker to run it. I would imagine it works just fine with Docker for Mac and Docker for Windows, but I haven’t tried them out.

Anyway, it’s a start.  I did run in to some interesting problems writing it which maybe I’ll write up in a future post.