A rust kubernetes controller for a CoreDB resource using kube-rs.
The Controller object reconciles CoreDB instances when changes to it are detected, writes to its .status object, creates associated events, and uses finalizers for guaranteed delete handling.
Run linting with cargo fmt and clippy
Clippy:
rustup component add clippy
cargo clippy
cargo fmt:
rustup component add rustfmt --toolchain nightly
cargo +nightly fmt
cargo test
Set your kubecontext to any namespace, and label it to indicate it is safe to run tests against this cluster (do not do against non-test clusters)
kubectl label namespace default safe-to-run-coredb-tests=true
Start or install the controller you want to test (see the following sections)
cargo test -- --ignored
--nocapture flag to show print statements during test runsAs an example; install kind. Once installed, follow these instructions to create a kind cluster connected to a local image registry.
Apply the CRD from cached file, or pipe it from crdgen (best if changing it):
sh
cargo run --bin crdgen | kubectl apply -f -
Setup an opentelemetry collector in your cluster. Tempo / opentelemetry-operator / grafana agent should all work out of the box. If your collector does not support grpc otlp you need to change the exporter in main.rs.
sh
cargo run
cargo install cargo-watch
Then, run with auto-reload
cargo watch -x 'run'
Or, with optional telemetry (change as per requirements):
sh
OPENTELEMETRY_ENDPOINT_URL=https://0.0.0.0:55680 RUST_LOG=info,kube=trace,controller=debug cargo run --features=telemetry
Compile the controller with:
sh
just compile
Build an image with:
sh
just build
Push the image to your local registry with:
sh
docker push localhost:5001/controller:<tag>
Edit the deployment's image tag appropriately, then run:
sh
kubectl apply -f yaml/deployment.yaml
kubectl port-forward service/coredb-controller 8080:80
NB: namespace is assumed to be default. If you need a different namespace, you can replace default with whatever you want in the yaml and set the namespace in your current-context to get all the commands here to work.
In either of the run scenarios, your app is listening on port 8080, and it will observe CoreDB events.
Try some of:
sh
kubectl apply -f yaml/sample-coredb.yaml
kubectl delete coredb sample-coredb
kubectl edit coredb sample-coredb # change replicas
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 coredb -o yaml.
The sample web server exposes some example metrics and debug information you can inspect with curl.
```sh $ kubectl apply -f yaml/sample-coredb.yaml $ curl 0.0.0.0:8080/metrics
cdbcontrollerreconciledurationsecondsbucket{le="0.01"} 1 cdbcontrollerreconciledurationsecondsbucket{le="0.1"} 1 cdbcontrollerreconciledurationsecondsbucket{le="0.25"} 1 cdbcontrollerreconciledurationsecondsbucket{le="0.5"} 1 cdbcontrollerreconciledurationsecondsbucket{le="1"} 1 cdbcontrollerreconciledurationsecondsbucket{le="5"} 1 cdbcontrollerreconciledurationsecondsbucket{le="15"} 1 cdbcontrollerreconciledurationsecondsbucket{le="60"} 1 cdbcontrollerreconciledurationsecondsbucket{le="+Inf"} 1 cdbcontrollerreconciledurationsecondssum 0.013 cdbcontrollerreconciledurationseconds_count 1
cdbcontrollerreconciliationerrorstotal 0
cdbcontrollerreconciliationstotal 1 $ curl 0.0.0.0:8080/ {"lastevent":"2019-07-17T22:31:37.591320068Z"} ```
The metrics will be auto-scraped if you have a standard PodMonitor for prometheus.io/scrape.