FROM ubuntu

Today most docker containers are based on ubuntu or debian images, which result in quite a big amount of data per container. Most included data is never needed by the containing application.

docker images gives a good overview about the sizes of images.

Especially containers containing small amounts of data like tooling scripts profit from a smaller base image.

There are a couple of ways to get a smaller base image, which are shown below.

From scratch - 0 MB

If your container brings all needed dependencies or is a statically compiled binary your best choice is to begin from scratch. Which means a 0-Byte empty base image.

You might pull the scratch image from docker hub, i experienced that’s not possible with some versions of docker, but you can simply build it yourself:

tar cv --files-from /dev/null | docker import - empty

This command creates an empty image called empty.

FROM empty

Bare in mind that this container does not even has a shell.

Busybox - 5.6 MB

If you need at least a small shell to look if everything is in the right place, busybox might be a good choice. busybox comes with the busybox shell and the basic small unix utilities.

docker pull busybox
FROM busybox

For some scripts the basic busybox shell is not sufficient and there’s no bash included.

Busybox with bash - 5.9 MB

Fear not, there’s also a way to build busybox with bash.

FROM progrium/busybox

RUN opkg-install bash

Or simply pull blang/busybox-bash.

Alpine - 5.0 MB

A very good base for a small image is gliderlabs/alpine (Docs). It comes with a small package manager apk.

docker pull gliderlabs/alpine
FROM gliderlabs/alpine

Alpine comes with a small shell, if you need a full bash, the next option is your choice.

Alpine with bash - 6.5 MB

Alpine with an installed bash is probably the best choice if you need an extendable image with bash and a package mananger.

FROM gliderlabs/alpine
RUN apk-install bash

You might try this, pull blang/alpine-bash.