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Working on CoreOS Assembler

This page is about CoreOS Assembler development. See the Building Fedora CoreOS and Working with CoreOS Assembler guides if you are looking for how to use the CoreOS Assembler.

  1. Hacking on CoreOS Assembler Scripts
  2. Installing cosa inside an existing container
  3. Building the cosa container image locally
  4. Developing on coreos-assembler remotely
  5. Pulling in fixed packages into the COSA container
  6. Running Unit Tests
  7. Adding/Updating kola Tests in coreos-assembler

Hacking on CoreOS Assembler Scripts

If you find yourself wanting to hack on CoreOS Assembler itself then you can easily mount the scripts into the container and prevent rebuilding the container to test every change. This can be done using the COREOS_ASSEMBLER_GIT env var.

$ export COREOS_ASSEMBLER_GIT=/path/to/github.com/coreos/coreos-assembler/
$ cosa init https://github.com/coreos/fedora-coreos-config.git
$ cosa fetch && cosa build

Installing cosa inside an existing container

If you already have a pet container you’d like to keep using that matches the same Fedora release cosa uses, you can install cosa inside of it by doing:

$ sudo ./build.sh configure_yum_repos
$ sudo ./build.sh install_rpms
$ make
$ sudo make install

From that point on, you only need to run make && sudo make install if you’re hacking on cosa itself (unless there are new RPM requirements added).

You can also reuse a cosa shell to test changes from other git repositories. You’ll likely want to do this for e.g. things like testing out changes to ostree/rpm-ostree that are run as part of cosa build.

Building the cosa container image locally

To completely rebuild the COSA container image locally, use:

$ podman build -t localhost/coreos-assembler .

You should then set COREOS_ASSEMBLER_CONTAINER=localhost/coreos-assembler in the environment if you’re using the bash alias cosa:

$ export COREOS_ASSEMBLER_CONTAINER=localhost/coreos-assembler
$ cosa ...

You can also use Dockerfile.dev to create a new container image based on the official one with your local cahnges:

$ podman build -f Dockerfile.dev -t localhost/coreos-assembler

Developing on coreos-assembler remotely

Many coreos-assembler developers use podman locally. However some things may only reproduce in a Kubernetes/OpenShift environment. One trick is to spin up a pod with coreos-assembler with an entrypoint of sleep infinity, then use oc rsh to log into it.

A further trick you can use is oc rsync to copy the build from your workstation to the remote pod for fast iteration. For example, assuming a remote pod name of walters-cosa:

oc rsync ./ walters-cosa:/home/builder/coreos-assembler/ && oc rsh walters-cosa sudo /bin/sh -c 'cd ~builder/coreos-assembler && make install'

(This could be improved in various ways, among them just shipping the binaries and not the source)

Pulling in fixed packages into the COSA container

To pull in fixed packages before they make it through Bodhi, you can simply tag them into the f${releasever}-coreos-continuous tag and trigger a rebuild.

Running Unit Tests

  1. Ensure that pytest and pytest-cov are installed:
$ pip3 install --user -r test-requirements.txt
  1. Run pytest on the tests directory
$ pytest tests/
============================= test session starts ==============================
platform linux -- Python 3.7.3, pytest-4.6.3, py-1.8.0, pluggy-0.12.0
rootdir: /var/home/steve/Tech/GITHUB/coreos-assembler, inifile: pytest.ini
plugins: cov-2.7.1
collected 3 items

tests/test_cli.py ...                                                    [100%]

----------- coverage: platform linux, python 3.7.3-final-0 -----------
Name                      Stmts   Miss  Cover
---------------------------------------------
src/cosalib/__init__.py       0      0   100%
src/cosalib/build.py        127    127     0%
src/cosalib/cli.py           28      0   100%
---------------------------------------------
TOTAL                       155    127    18%


=========================== 3 passed in 0.05 seconds ===========================

Adding/Updating kola Tests in coreos-assembler

For adding tests to kola, please see the Testing with Kola page.

You can then run make to build your modifications.