vergenzt / generate-dockerignore-from-gitignore

.dockerignore file generator based on .gitignore file(s)

generate-dockerignore-from-gitignore

As the name implies, this package generates a .dockerignore for you based on .gitignore rules found in your source tree.

Why generate this file, you ask? Because there are a number of differences between .dockerignore and .gitignore rule processing which can make it non-trivial to make your Docker file tree match your local git tree.

Generating your .dockerignore file based on your configured .gitignore rules means you only have to think about which files should not be distributed with your project only once. This also can promote reproducible builds by ensuring that the only files your Docker context has access to are those files that are tracked by your git repository.

The following differences between .dockerignore vs .gitignore processing are handled by this tool:

behavior	.gitignore	.dockerignore
plain patterns without slashes or wildcards	⏬️ match recursively	⬆️ match top-level only
separate per-directory ignore files	✅ allowed	❌ not allowed
local .git/info/exclude file	✅ included	-
global core.excludesFile file	✅ included	-

The code's handling of these behavioral differences is tested using actual git and Docker calls, followed by validation that the resultant git source trees are equal to the Docker build contexts.

References:

• https://git-scm.com/docs/gitignore
• https://docs.docker.com/engine/reference/builder/#dockerignore-file

Installation

pip install generate-dockerignore-from-gitignore

Usage

usage: generate-dockerignore [-h] [-C DOCKER_ROOT] [-v] [-o OUTPUT] [PATH ...]

.dockerignore file generator based on .gitignore file(s)

positional arguments:
  PATH                  gitignore file(s), or directories under git source control (which will be
                        searched for **/.gitignore).

options:
  -h, --help            show this help message and exit
  -C DOCKER_ROOT, --docker-root DOCKER_ROOT
                        Docker context directory to chdir into before continuing
  -v, --verbose         Output per-file logging to stderr
  -o OUTPUT, --output OUTPUT
                        File path for generated .dockerignore rule output, or - for stdout
                        (default: .dockerignore)