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Make Gadgets docker Makefile

This directory contains a Makefile with docker helper targets. They can be imported to extend your makefile or called directly.

Docker tools Makefile

This directory contains a Makefile that enhance vanilla docker with make.

The Makefile also provides several practical targets that wrap the functionality of the docker-image-cacher.sh tool provided in this project.

To consume the provided targets/recipes from the project you can directly import the desired module to your Makefile such as follows: 

include make_gadgets/docker/docker-tools.mk

To include the docker-image-cacher target/recipes add the following to the top of your Makefile:

include make_gadgets/docker/docker-image-cacher.mk

You can directly call the provided targets/recipes by calling make directly on this directory:

cd make_gadgets/docker
make docker_save
...
make docker_load
...
make docker_orbital_cannon

docker-image-cacher.sh

The docker-image-cacher.sh is a utility script for batch caching/saving and loading docker images to archives with the goal of saving network resources and quotas.

There are several major functions this script offers namely fetching, saving, loading, and printing. All of these will be discussed in the coming sections.

Image Discovery

The docker-image-cacher.sh uses a very simple strategy for discovering docker images to fetch and cache: 1. The image search path is searched and scraped recursively for Dockerfiles containing 'from ' - If no search path is provided then the docker image list is assumed from the docker local registry e.g., everything in 'docker image ls' - If the local registry is empty then only images provided in the inclusion list are added 2. All images provided in the inclusion list are appended to the found images 3. All images from the exclusion list are removed from the found images

Image discovery is used for fetching, caching/saving, and printing.

Printing

you can call docker-image-cacher.sh with the -p or --print flag to perform a print operation.

The print operation or action simply prints the docker image list that will be fetched and cached/saved with their respective operations.

Printing preempts all other actions, the list of docker images will be printed and the program will exit.

Fetching

You can call docker-image-cacher.sh with the -f or --fetch flag to perform a fetch operation.

There are two ways this can be done. The fist way provides a docker image search path as a basis to collect a list of images to fetch as in the following example:

bash docker-image-cacher.sh --docker-image-search-path "<some search path>" --fetch

All Dockerfiles in the search path provided will be recursively searched for the docker key word "FROM". Any image that is referenced by "FROM IMAGE:TAG" in any Dockerfile within the search path will be fetched with docker using the docker pull command.

The second way to fetch docker images is to provide no search path such as follows:

bash docker-image-cacher.sh --fetch

This will effectively update every image already loaded into docker on your host.

Saving/Caching

Saving can be called in several ways. The first way is providing a cache directory and search path:

bash docker-image-cacher.sh --docker-image-search-path "<some search path>" --docker-image-cache-directory "<cache dir to save images to>" --save

resulting in every discovered docker image will be saved into the default docker image cache directory as an archive for each image.

Another way save can be called is providing a search path but no cache directory:

bash docker-image-cacher.sh --docker-image-search-path "<some search path>" --save

The image archives will be saved to the default cache path.

Another way to call save is without a search path such as follows:

bash docker-image-cacher.sh --save

Every image in the docker registry will be saved to disk as a tar archive into the default docker image cache directory.

In order for save to work all docker images in the image list must exist in the docker registry. An image can be added to the registry in multiple ways: - Calling 'docker build' on a Dockerfile containing an image reference will pull it to the local registry - Calling 'docker pull ' - Using docker-image-cacher.sh with the --fetch flag to batch pull a list of images.

Loading

All images that are cached as tar archives in the default docker image cache directory will be loaded into the docker registry.

bash docker-image-cacher.sh --load

You can also load all docker images from a specific cache directory:

bash docker-image-cacher.sh --docker-image-cache-directory "<some cache dir>" --load

Help

To view more documentation on this tool you can run the help flag:

bash docker-image-cacher.sh --help

Use Cases

This section will give a few practical use cases for the docker-image-cacher.sh tool

Scrape your home directory for docker images, fetch them, and save them

bash docker-image-cacher.sh -docker-image-search-path "${HOME}" --fetch --save

Your home directory must have at least one Dockerfile somewhere in the directory tree.

Save all docker images in the local registry to the default cache location

bash docker-image-cacher.sh --save

Load docker images from the default cache location into the local registry

bash docker-image-cacher.sh --load

Fetch and save the docker image 'ubuntu:latest'

bash docker-image-cacher.sh --save --fetch -i 'ubuntu:latest'

and later 'ubuntu:latest' can be loaded from disk back into the local registry with:

bash docker-image-cacher.sh --load

Fetch and save the docker image 'ubuntu:latest' and 'alpine:latest'

bash docker-image-cacher.sh --save --fetch -i 'ubuntu:latest alpine:latest'

and later both 'ubuntu:latest' and 'alpine:latest' can be loaded from disk back into the local registry with:

bash docker-image-cacher.sh --load