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Docker Alpine

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Learn about the benefits of using the Docker Alpine image. We will go over what the Alpine Linux distribution is and why it is so small.

Table of Contents 📖

Docker Alpine

Docker Alpine is a lightweight Linux distribution. One reason Alpine is so lightweight is that it comes with minimal utilities pre-installed. This also makes Alpine more secure as it lowers the attack surface. We can check the size of the Alpine image by spinning up a container and using docker ps.

docker run -it --name my-alpine-c alpine:3.14
docker ps --size
f24a3c3214d3   alpine:3.14       "/bin/sh"                7 seconds ago   Up 6 seconds                                             my-alpine-c           0B (virtual 5.35MB)

Due to Alpine's security and lightweight nature, it is often used as a base image in Docker builds.

INFO: Alpine is built around musl libc and BusyBox. libc is a library that Linux requires to run.

Installing Packages

Even though Alpine comes with a minimal set of utilities, we can install packages with apk, Alpine's package management tool.

apk add --no-cache mysql-client
mysql
ERROR 2002 (HY000): Can't connect to local server through socket '/run/mysqld/mysqld.sock' (2)

Of course, adding packages like this will increase the size of the container.

docker ps --size
CONTAINER ID   IMAGE             COMMAND                  CREATED         STATUS                PORTS                              NAMES                 SIZE
f24a3c3214d3   alpine:3.14       "/bin/sh"                7 seconds ago   Up 6 seconds                                             my-alpine-c           0B (virtual 5.35MB)

docker ps --size
CONTAINER ID   IMAGE             COMMAND                  CREATED              STATUS                PORTS                              NAMES                 SIZE
f24a3c3214d3   alpine:3.14       "/bin/sh"                About a minute ago   Up About a minute                                        my-alpine-c           34.6MB (virtual 39.9MB)

Pre-Installed Alpine Images

There are also many Docker images that have a desired package or library pre-installed on the Alpine Linux distribution. For example, Nginx and Node.

docker pull nginx
docker pull nginx:alpine
docker images
REPOSITORY                                TAG                                        IMAGE ID       CREATED         SIZE
nginx                                     alpine                                     70594c812316   3 weeks ago     47MB
nginx                                     latest                                     a9dfdba8b719   3 weeks ago     193MB

docker pull node
docker pull node:alpine
docker images
REPOSITORY                                TAG                                        IMAGE ID       CREATED         SIZE
node                                      alpine                                     3f776ed3998d   44 hours ago    152MB
node                                      latest                                     8018d9bdf679   44 hours ago    1.11GB
Docker Alpine