A rust kubernetes controller for a Foo
resource using kube-rs.
The Controller
object reconciles Foo
instances when changes to it are detected, and writes to its .status object.
A kube cluster / minikube. Install the CRD and an instance of it into the cluster:
cargo run --bin crdgen > yaml/foo-crd.yaml
kubectl apply -f yaml/foo-crd.yaml
# then:
kubectl apply -f yaml/instance-bad.yaml
You need a valid local kube config with sufficient access (clux
service account has sufficient access if you want to impersonate the one in yaml/access.yaml
).
Start the server with cargo run
:
cargo run
Deploy as a deployment with scoped access via a service account. See yaml/deployment.yaml
as an example.
kubectl apply -f yaml/deployment.yaml
sleep 10 # wait for docker pull and start on kube side
export FOO_POD="$(kubectl get pods -n default -lapp=foo-controller --no-headers | awk '{print $1}')"
kubectl port-forward ${FOO_POD} -n default 8080:8080 # keep this running
Once the app is running, you can see that it observes foo
events.
Try some of:
kubectl apply -f yaml/instance-good.yaml -n default
kubectl delete foo good -n default
kubectl edit foo good # change info to contain bad
The reconciler will run and write the status object on every change. You should see results in the logs of the pod, or on the .status object outputs of kubectl get foos -oyaml
.
The sample web server exposes some example metrics and debug information you can inspect with curl
.
$ kubectl apply -f yaml/instance-good.yaml -n default
$ curl 0.0.0.0:8080/metrics
# HELP handled_events handled events
# TYPE handled_events counter
handled_events 1
$ curl 0.0.0.0:8080/
{"last_event":"2019-07-17T22:31:37.591320068Z"}
The example reconciler
only checks the .spec.info
to see if it contains the word bad
. If it does, it updates the .status
object to reflect whether or not the instance is_bad
.
While this controller has no child objects configured, there is a configmapgen_controller
example in kube-rs.