Docker build automation

Overview

This package provides a script which builds multiple Docker containers in sequence, using the contents of a docker_images.txt file in some directory. This file is tab-delimited, and lines starting with # are ignored.

Each non-comment line in docker_images.txt is of the format:

label    path/to/Dockerfile    comma,separated,options,if,desired

(with arbitrary whitespace between pieces). By default, images will be built by running docker build -t label -f Dockerfile . in the parent directory of the Dockerfile. Add the option base_directory_build after the Dockerfile to specify that the image should be built with:

docker build -t label -f path/to/Dockerfile .

in the directory containing docker_images.txt instead. If the default behavior is acceptable, the third tab-delimited piece of each line can be omitted.

Docker images will be built in sequence, so images can refer to the results of previous images, e.g.:

image-base    base/Dockerfile
image-dev     dev/Dockerfile

with dev/Dockerfile containing:

FROM image-base
...

Since images are unconditionally built with the latest tag, first, then tagged with a timestamp if desired, no Dockerfile needs to be modified for a "release" image.

The container build script checks for any uninitialized Git submodules, and by default refuses to build if any are found. This can be overridden if desired (see below).

The build option write_git_version accepts a file path argument, to which the output of git describe --dirty --always --abbrev=12 is written. For example:

image_label    path/to/Dockerfile    write_git_version=src/revision.txt

Cross-platform builds

The build option platforms accepts a &-delimited list of platforms, which will be passed directly to docker build --platforms=..., with & replaced by , in the docker build invocation. Note that this may require usage of the newer buildx tool, replacing the legacy docker build.

Usage

The command-line entry point provided by this script is build_docker_images. By default, images will be tagged with :latest appended to the base image name.

Options:

--tag-timestamp
	In addition to tagging images as latest, also tag with a timestamp in YYYYMMDD-HHmmss format. All images in docker_images.txt are tagged with the same timestamp. Can be combined with --tag=tag_name.
--tag=tag_name	In addition to tagging images as latest, also tag with the tag name provided. All images in docker_images.txt are tagged with the same tag name. Can be combined with --tag-timestamp.
--push	Push all built containers to Docker Hub, tagged as latest and with any additional tags specified via --tag-timestamp or --tag=tag_name.
--ignore-missing-submodules
	Allow building Docker containers if git submodule reports that at least one submodule is uninitialized.
--pretend	Run in pretend mode: don't actually execute anything (building, tagging, pushing).

Requirements

Python 3.6 or newer for this script. Docker to build/tag/push images (version unimportant).