I played with CHICKEN Scheme, Docker and Alpine Linux

:: IT, Lisp, Scheme, CHICKEN, Docker, Linux

I am looking forward to meet LISP people at the 32c3’s LISP assembly. The last days I played a bit with different Scheme implementations including CHICKEN scheme. The main feature of CHICKEN is that it compiles the Scheme code to C and then creates dynamic libraries and binaries with the C compiler. I thought that combining these binaries with a minimal Docker container could give me a very small deployment. So here are my steps:

Choosing Alpine Linux as a “small” Linux

The smallest Linux image for Docker is undoubtly busybox with a size of about 2.489 MB. But busybox lacks a package manager which makes installing software painful. Therefore I have chosen Alpine Linux which comes with package manager and it’s image’s size is about 5.234 MB. That’s double the size of the busybox image but still quite small compared to the Ubuntu image which is about 266 MB.

Creating a Docker container with CHICKEN

Alpine Linux comes with the musl libc and I thought it would be best to compile all the CHICKEN stuff with that libc. Therefore I created a Docker container with gcc and all the other stuff with this Dockerfile (Github repository):

FROM alpine:3.2

RUN apk update && apk add make gcc musl-dev 
RUN wget -O - http://code.call-cc.org/releases/4.10.0/chicken-4.10.0.tar.gz | tar xz

WORKDIR /chicken-4.10.0

RUN make PLATFORM=linux && make PLATFORM=linux install

RUN rm -fr /chicken-4.10.0 

WORKDIR /

CMD ["csi"]

This image is quite big (about 161.7 MB) and is available for download at the Docker Hub.

Compiling some CHICKEN code

For testing purposes I wanted a minimal web server running in the Alpine Linux image. Therefore I looked through the egg index and found spiffy. I fired up the chicken-alpine container (but I used ash as command instead of the csi Scheme interpreter) and created a small web server that serves some static pages. I wrote a main.scm:

(use spiffy)
(start-server)

and added some static pages to a ./web sub-directory. Then everything had to be compiled and prepared for deployment:

chicken-install spiffy
csc -deploy main.scm
chicken-install -deploy -p $PWD/main spiffy

Deploy in a fresh Alpine Linux image

After the compilation I copied the main and web directories on my host machine using docker cp and created the following Dockerfile:

FROM alpine:3.2

ADD main /main
ADD web main/web
WORKDIR main

CMD /main/main

and let docker build -t krrrcks/spiffy-test . do the job. The size of the resulting image is about 12.37 MB and that’s pretty small. I uploaded that image to the Docker Hub as well.

To serve the pages I did a docker run -d -p 8080:8080 krrrcks/spiffy-test (spiffy listens on port 8080 in the default install) and browsed my static pages.