docker-alpine

The official Docker image for Alpine Linux. The image is only 5MB and has access to a package repository that is much more featureful 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      CREATED      SIZE
alpine      latest  961769676411  4 weeks ago  5.58MB
ubuntu      latest  2ca708c1c9cc  2 days ago   64.2MB
debian      latest  c2c03a296d23  9 days ago   114MB
centos      latest  67fa590cfc1c  4 weeks ago  202MB

There are images such as progrium/busybox which get us 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 featureful 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 alpine apk add --no-cache nodejs
fetch http://dl-cdn.alpinelinux.org/alpine/v3.9/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.9/community/x86_64/APKINDEX.tar.gz
(1/7) Installing ca-certificates (20190108-r0)
(2/7) Installing c-ares (1.15.0-r0)
(3/7) Installing libgcc (8.3.0-r0)
(4/7) Installing http-parser (2.8.1-r0)
(5/7) Installing libstdc++ (8.3.0-r0)
(6/7) Installing libuv (1.23.2-r0)
(7/7) Installing nodejs (10.14.2-r0)
Executing busybox-1.29.3-r10.trigger
Executing ca-certificates-20190108-r0.trigger
OK: 31 MiB in 21 packages

This makes Alpine Linux a great image base for utilities, as well as production applications. Read more about Alpine Linux here and it will become obvious how its mantra fits in right at home with Docker images.

Note	All of the example outputs above were last generated/updated on May 3rd 2019.

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 28 seconds to build and yields a 169 MB image. Start doing this:

FROM alpine:3.9
RUN apk add --no-cache mysql-client
ENTRYPOINT ["mysql"]

Only 4 seconds to build and results in a 41 MB image!