README.md

Once you have static binaries you want to create the smallest possible docker container.

Requirements:

• automated/trusted build: so you have to put your Dockerfile into github
• a minimal docker image, so even alpine or busybox is big (compared to your binry which is probably under 1MB)
• don’t store the binary redundantly in github near to the Dockerfile

This Docker image is my proposed solution.

Usage

FROM lalyos/scratch-chmx
ADD https://bintray.com/yourpackage/v1.2.3/mycli /bin/mycli
RUN ["/bin/chmx", "/bin/mycli"]

ENTRYPOINT ["/bin/mycli"]

tl;dr

The plan is to create scratch based docker images with single static binaries. For example i want to dockerize upx

debian package

if you install it on top of debian:jessie

apt-get update && apt-get install -y upx

You end up with an image over 130 MB.

alpine

You can use alpine as a base. But unfortunately there is no official upx package. With some work, you can build a static version of upx around 500KB. If you put into alpine, its again over 5MB

scratch

If you put it into scratch, well it remains 500KB. The usual way to create a scratch base docker images:

FROM scratch
ADD upx /upx

But this way if you want an automated/trusted docker hub build, you have to put the binary into the git repo. Which shouldn’t be there.

So now the final Dockerfile should look like:

FROM scratch
ADD https://bintray.com/lalyos/upx/v1.2.3/upx /upx
RUN chmod +x /upx

But if you start from scratch there is no chmod ?!

lalyos/scratch-chmx

This can be solved by adding a small tool which is written in C and can perform a chmod +x. Static compiled chmx is about: 88KB.

Of course its dockerized as:

FROM scratch
ADD chmx /bin/chmx

Now you can create an upx container as:

FROM lalyos/scratch-chmx