Difficulty: Beginner
Estimated Time: 10 minutes

What is a container?

Step 1 of 3

Container Image

A container image is a tar file containing tar files. Each of the tar file is a layer. Once all tar files have been extract into the same location then you have the container's filesystem.

This can be explored via Docker. Pull the layers onto your local system.

docker pull redis:3.2.11-alpine

Export the image into the raw tar format.

docker save redis:3.2.11-alpine > redis.tar

Extract to the disk

tar -xvf redis.tar

All of the layer tar files are now viewable.


The image also includes metadata about the image, such as version information and tag names.

cat repositories

cat manifest.json

Extracting a layer will show you which files that layer provides.

tar -xvf da2a73e79c2ccb87834d7ce3e43d274a750177fe6527ea3f8492d08d3bb0123c/layer.tar