docker-alpine

A super small Docker image based on Alpine Linux. The image is only 5 MB and has access to a package repository that is much more complete than other BusyBox based images.

Why?

Docker images today are big. Usually much larger than they need to be. There are a lot of ways to make them smaller, but the Docker populace still jumps to the ubuntu base image for most projects. The size savings over ubuntu and other bases are huge:

REPOSITORY          TAG           IMAGE ID          VIRTUAL SIZE
gliderlabs/alpine   latest        9cfff538e583      4.803 MB
debian              latest        19134a8202e7      123.1 MB
ubuntu              latest        104bec311bcd      129 MB
centos              latest        67591570dd29      191.8 MB

There are images such as progrium/busybox which get us very close to a minimal container and package system. But these particular BusyBox builds piggyback on the OpenWRT package index which is often lacking and not tailored towards generic everyday applications. Alpine Linux has a much more complete and up to date package index:

$ docker run progrium/busybox opkg-install nodejs
Unknown package 'nodejs'.
Collected errors:
* opkg_install_cmd: Cannot install package nodejs.

$ docker run gliderlabs/alpine apk add --no-cache nodejs
fetch http://alpine.gliderlabs.com/alpine/v3.3/main/x86_64/APKINDEX.tar.gz
fetch http://alpine.gliderlabs.com/alpine/v3.3/community/x86_64/APKINDEX.tar.gz
(1/4) Installing libgcc (5.3.0-r0)
(2/4) Installing libstdc++ (5.3.0-r0)
(3/4) Installing libuv (1.7.5-r0)
(4/4) Installing nodejs (4.2.3-r0)
Executing busybox-1.24.1-r7.trigger
OK: 29 MiB in 15 packages

This makes Alpine Linux a great image base for utilities and even production applications. Read more about Alpine Linux here and you can see how their mantra fits in right at home with Docker images.

Usage

Stop doing this:

FROM ubuntu-debootstrap:14.04
RUN apt-get update -q \
  && DEBIAN_FRONTEND=noninteractive apt-get install -qy mysql-client \
  && apt-get clean \
  && rm -rf /var/lib/apt
ENTRYPOINT ["mysql"]

This took 19 seconds to build and yields a 164 MB image. Eww. Start doing this:

FROM gliderlabs/alpine:3.4
RUN apk add --no-cache mysql-client
ENTRYPOINT ["mysql"]

Only 3 seconds to build and results in a 36 MB image! Hooray!

Documentation

This image is well documented. Check out the documentation at Viewdocs and the docs directory in this repository.

Contacts

We make reasonable efforts to support our work and are always happy to chat. Join us in our Slack community or submit a GitHub issue if you have a security or other general question about this Docker image. Please email security or user mailing lists if you have concerns specific to Alpine Linux.

Inspiration

The motivation for this project and modifications to mkimage.sh are highly inspired by Eivind Uggedal (uggedal) and Luis Lavena (luislavena). They have made great strides in getting Alpine Linux running as a Docker container. Check out their mini-container/base image as well.

Sponsors

Fastly provides the CDN for our Alpine Linux package repository. This allows super speedy package downloads from all over the globe!

License

The code in this repository, unless otherwise noted, is BSD licensed. See the LICENSE file in this repository.