kured/DEVELOPMENT.md

Developing kured

We love contributions to kured, no matter if you are helping out on Slack, reporting or triaging issues or contributing code to kured.

In any case, it will make sense to familiarise yourself with the main README to understand the different features and options, which is helpful for testing. The "building" section in particular makes sense if you are planning to contribute code.

Updating k8s support

Whenever we want to update e.g. the kubectl or client-go dependencies, some RBAC changes might be necessary too.

This is what it took to support Kubernetes 1.14: https://github.com/weaveworks/kured/pull/75

That the process can be more involved that that can be seen in https://github.com/weaveworks/kured/commits/support-k8s-1.10

Once you updated everything, make sure you update the support matrix on the main README as well.

Release testing

Before kured is released, we want to make sure it still works fine on the previous, current and next minor version of Kubernetes (with respect to the embedded client-go & kubectl). For local testing e.g. minikube or kind can be sufficient.

Deploy kured in your test scenario, make sure you pass the right image, update the e.g. period and reboot-days options, so you get immediate results, if you login to a node and run:

sudo touch /var/run/reboot-required

Testing with minikube

A test-run with minikube could look like this:

# start minikube
minikube start --vm-driver kvm2 --kubernetes-version <k8s-release>

# build kured image and publish to registry accessible by minikube
make image minikube-publish

# edit kured-ds.yaml to
#   - point to new image
#   - change e.g. period and reboot-days option for immediate results

minikube kubectl -- apply -f kured-rbac.yaml
minikube kubectl -- apply -f kured-ds.yaml
minikube kubectl -- logs daemonset.apps/kured -n kube-system -f

# Alternatively use helm to install the chart
# edit values-local.yaml to change any chart parameters
helm install kured ./charts/kured --namespace kube-system -f ./charts/kured/values.minikube.yaml

# In separate terminal
minikube ssh
 sudo touch /var/run/reboot-required
minikube logs -f

Now check for the 'Commanding reboot' message and minikube going down.

Unfortunately as of today, you are going to run into https://github.com/kubernetes/minikube/issues/2874. This means that minikube won't come back easily. You will need to start minikube again. Then you can check for the lock release.

If all the tests ran well, kured maintainers can reach out to the Weaveworks team to get an upcoming kured release tested in the Dev environment for real life testing.

Testing with kind

A test-run with kind could look like this:

# create kind cluster
kind create cluster --config .github/kind-cluster.yaml

# create reboot required files on pre-defined kind nodes
./tests/create-reboot-sentinels.sh

# check if reboot is working fine
./tests/kind/follow-coordinated-reboot.sh

Publishing a new kured release

Prepare Documentation

Check that README.md has an updated compatibility matrix and that the url in the kubectl incantation (under "Installation") is updated to the new version you want to release.

Create a tag on the repo and publish the image

Before going further, we should freeze the code for a release, by tagging the code, and publishing its immutable artifact: the kured docker image.

make DH_ORG="weaveworks" VERSION="1.3.0" image

Then docker push the image. In the future, that might be automatically done when creating a tag on the repository, with the help of github actions.

Prepare Helm chart

You should also check that the helm chart has been updated before issuing a release. You can bump the helm chart with the latest image tag by running:

make DH_ORG="weaveworks" VERSION="1.3.0" helm-chart

Finally bump the version in charts/kured/Chart.yaml (following the versioning rules) and you should be all set.

Create the combined manifest

Now create the kured-<release>-dockerhub.yaml for e.g. 1.3.0:

VERSION=1.3.0
MANIFEST="kured-$VERSION-dockerhub.yaml"
make DH_ORG="weaveworks" VERSION="${VERSION}" manifest
cat kured-rbac.yaml > "$MANIFEST"
cat kured-ds.yaml >> "$MANIFEST"

Publish release artifacts

Now you can head to the Github UI, use the version number as tag and upload the kured-<release>-dockerhub.yaml file.

The creation of the release will publish the helm chart (thanks to github actions).

Please describe what's new and noteworthy in the release notes, list the PRs that landed and give a shout-out to everyone who contributed.

Please also note down on which releases the upcoming kured release was tested on. (Check old release notes if you're unsure.)