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+# Developer Guide
+
+[TOC]
+
+## Code Review
+
+This project uses Gerrit for code review:
+https://gerrit-review.googlesource.com/
+which uses the ["git push" workflow][1] with server
+https://gerrit.googlesource.com/k8s-gerrit. You will need a
+[generated cookie][2].
+
+Gerrit depends on "Change-Id" annotations in your commit message.
+If you try to push a commit without one, it will explain how to
+install the proper git-hook:
+
+```
+curl -Lo `git rev-parse --git-dir`/hooks/commit-msg \
+ https://gerrit-review.googlesource.com/tools/hooks/commit-msg
+chmod +x `git rev-parse --git-dir`/hooks/commit-msg
+```
+
+Before you create your local commit (which you'll push to Gerrit)
+you will need to set your email to match your Gerrit account:
+
+```
+git config --local --add user.email foo@bar.com
+```
+
+Normally you will create code reviews by pushing for master:
+
+```
+git push origin HEAD:refs/for/master
+```
+
+## Developing container images
+
+When changing or creating container images, keep the image size as small as
+possible. This reduces storage space needed for images, the upload time and most
+importantly the download time, which improves startup time of pods.
+
+Some good practices are listed here:
+
+- **Chain commands:** Each `RUN`-command creates a new layer in the docker image.
+Each layer increases the total image size. Thus, reducing the number of layers,
+can also reduce the image size.
+
+- **Clean up after package installation:** The package installation creates a
+number of cache files, which should be removed after installation. In Ubuntu/Debian-
+based images use the following snippet (This requires `apt-get update` before
+each package installation!):
+
+```docker
+RUN apt-get update && \
+ apt get install -y <packages> && \
+ apt-get clean && \
+ rm -rf /var/lib/apt/lists/*
+```
+
+In Alpine based images use the `--no-cache`-flag of `apk`.
+
+- **Clean up temporary files immediately:** If temporary files are created by a
+command remove them in the same command chain.
+
+- **Use multi stage builds:** If some complicated build processes are needed for
+building parts of the container image, of which only the final product is needed,
+use [multi stage builds][3]
+
+
+[1]: https://gerrit-review.googlesource.com/Documentation/user-upload.html#_git_push
+[2]: https://gerrit.googlesource.com/new-password
+[3]: https://docs.docker.com/develop/develop-images/multistage-build/
+
+## Writing clean python code
+
+When writing python code, either for tests or for scripts, use `black` and `pylint`
+to ensure a clean code style. They can be run by the following commands:
+
+```sh
+pipenv install --dev
+pipenv run black $(find . -name '*.py')
+pipenv run pylint $(find . -name '*.py')
+```