add development docs

DEVELOPMENT.md

@@ -0,0 +1,91 @@
+# Developing `kured`
+
+We love contributions to `kured`, no matter if you are [helping out on
+Slack][slack], reporting or triaging [issues][issues] or contributing code
+to `kured`.
+
+In any case, it will make sense to familiarise yourself with the main
+[README][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.
+
+[slack]: README.md#getting-help
+[issues]: https://github.com/weaveworks/kured/issues
+[readme]: README.md
+
+## Updating k8s support
+
+Whenever we want to update e.g. [`kubectl` in the
+image](cmd/kured/Dockerfile), we need to consider if we update `client-go`
+as well, 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][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` 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:
+
+```console
+sudo touch /var/run/reboot-required
+```
+
+### Testing with `minikube`
+
+A test-run with `minikube` could look like this:
+
+```console
+minikube start --vm-driver kvm2 --kubernetes-version <k8s-release>
+
+# 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
+
+# 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.
+
+## Publishing a new kured release
+
+This is the most straight-forward in the whole process.
+
+Picking a suitable tag and creating the release through the Github UI should
+release the image just fine.
+
+### Release notes
+
+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.

README.md

@@ -277,6 +277,11 @@ make
 GO111MODULE=on make
 ```
 
+If you are interested in contributing code to kured, please take a look at
+our [development][development] docs.
+
+[development]: DEVELOPMENT.md
+
 ## Frequently Asked/Anticipated Questions
 
 ### Why is there no `latest` tag on Docker Hub?