dubo-dubon-duponey / dckr

Lets you transparently run your projects build / test commands inside containers

dckr

dckr is a simple, no dependency shell-script that transparently lets you develop your project inside containers.

For example, assuming you have a project where you would typically run:

ls -lA
cat foo
make thing
yarn test

Just call:

dckr ls -lA
dckr cat foo
dckr make thing
dckr yarn test

Or without the noise:

dckr ls -lA 2>/dev/null

That's it.

No boilerplate, no container setup, no monkeying around.

Controlling the base image

You can control what base operating system will be used for the container using the TARGET environment variable:

TARGET=ubuntu-lts-current dckr make all

TARGET values provided by default are visible in dckr.Dockerfile.

If TARGET is not specified, the latest current Debian is going to be used.

Using your own images

You can taylor this to your needs (probably you want your favorite language runtime and tools installed) by creating a Dockerfile anywhere (start by copying dckr.Dockerfile.example), and invoking dckr with the DOCKERFILE variable:

DOCKERFILE=thingie/Dockerfile TARGET=some-target dckr ls -lA

Be sure to either inherit one of the base com.dbdbdp.dckr:FOO images (defined in dckr.Dockerfile), or add the following to your custom image:

WORKDIR /dckr-project-mount
VOLUME /dckr-project-mount

You may also want to downgrade to USER dckr in your custom dockerfile after you are done installing packages for example.

"Live" containers

After the first invocation, the container is "live" (eg: kept around), and changes in your project folder are reflected inside the container immediately.

This means a couple of important things:

• commands are cumulative... just like they are on your local system...
• calling on further commands after the first one is very fast (in a shell, the overhead is the cost of exec-ing and docker IO)

How to install

On macOS:

brew install dubo-dubon-duponey/brews/dckr

Otherwise (or if you don't brew):

• clone "somewhere"
• add "somewhere" to your path

CI

In order to avoid rebuilding all the base images at each CI run, you can leverage dckr cache:

CACHE_DIR=somewhere dckr

And instruct your CI to cache somewhere.

Gotcha

Expect running complicated shell commands to be challenging (you have to get your escaping right).

Keep it simple.

This is mostly meant to be used for stuff like:

dckr make test thingie

Also, the very first run of dckr will be SLOW (as it will download all base images).

Develop dckr

You need docker, shellcheck and hadolint installed.

./test.sh must pass.

This project is not...

• the proper way to docker-ize your application for production
• meant to be used to reproduce complex, multi-containers applications
• a replacement for compose