tocker: TDD for writing Dockerfile

About

tocker is a plugin for testinfra that allows developers to test docker images

Getting Started

pip install tocker

Set your environment variables to connect to docker engine:

export DOCKER_HOST=unix:///var/run/docker.sock

If docker engine runs a different host, set the following:

export DOCKER_TLS_VERIFY=1
export DOCKER_HOST=tcp://ip:port
export DOCKER_CERT_PATH=/path/to/certs

If you're using docker-machine, you can simply run:

eval $(docker-machine env myenv)

Workflow

1. Create a Dockerfile
2. Create a test.py in the same directory
3. Add IMAGE_TAG to test.py. E.g: mycorp/nginx:1.9.12
4. Write your tests (find out more about how to use different modules from testinfra docs)
5. Run testinfra test.py (-s -v for verbose mode)
6. Watch your tests fail
7. Edit your Dockerfile until the tests pass
8. When you're happy docker push the image

How does it work?

• tocker builds an image from Dockerfile
• The image will be tagged with IMAGE_TAG
• When the image is successfully built, a new container is created
• Tests are run against the created container with docker exec
• The container is destroyed at the end of all test cases
• tocker uses docker build cache so the consecutive runs are fast
• The resulting image is not removed

Contribute

If you're looking to add a new module, please contribute to testinfra.

If it's more specific to Docker, you can add additional fixtures under tocker/fixtures.py. Pull requests are welcome.