Add active health checks doc and manifest

Author: OguzPastirmaci

docs/running-active-health-checks.md

@@ -0,0 +1,50 @@
+# Running Active Health Checks (preview)
+
+> [!NOTE]  
+> This is a preview feature. We are actively adding more tests.
+
+This directory contains the manifests required to run the NCCL-based active health checks on GPU nodes using Volcano. It includes a smart applier CronJob that only schedules tests on idle nodes that were not already tested in the last 24 hours (configurable).
+
+## Node selection logic
+
+When the CronJob runs, the applier script performs the following steps:
+
+1. **Enumerate GPU nodes** Look for nodes that have (`nvidia.com/gpu=true`) label.
+2. **Check current usage:** It sums the GPU requests across running pods on each node. Only nodes with zero GPU usage are considered idle.
+3. **Exclude recently tested nodes:** If a node is labeled `oke.oraclecloud.com/active-health-checks-nccl-tests-last-run` with in the last 24 hours, it is skipped.
+4. **Require at least two nodes:** Both worker nodes must be available. If fewer than two nodes remain, the job exits gracefully.
+5. **Shape detection:** The selected node’s `node.kubernetes.io/instance-type` label determines which ConfigMap manifest to apply.
+6. **Job creation:** A Volcano `Job` is created with a launcher (`mpimaster`) and workers (`mpiworker`). The launcher waits for SSH connectivity to the workers before running the NCCL test.
+7. **Label updates:** After the run, nodes are labeled with the latest result and timestamp.
+
+If all nodes are excluded (either busy or already tested), the job exits without creating a Volcano job, logging the reason.
+
+## Usage
+The manifest assumes there's a namespace called `monitoring`. If you want to deploy to another namespace, edit the manifest accordingly.
+
+1. **Apply manifests**
+   ```bash
+   kubectl apply -f https://github.com/oracle-quickstart/oci-hpc-oke/tree/main/manifests/active-health-checks/active-health-checks-nccl-tests.yaml
+   ```
+
+2. **Run ad-hoc test**
+   ```bash
+   kubectl create job -n monitoring --from=cronjob/active-health-checks-nccl-tests-applier test-$(date +%s)
+   
+   kubectl logs -n monitoring job/shape-test-<timestamp>
+   ```
+
+3. **Watch Volcano job**
+   ```bash
+   kubectl get pods -n monitoring -l volcano.sh/job-name=<job-name>
+   
+   kubectl logs -n monitoring <launcher-pod>
+   ```
+
+4. **Clean up**
+   ```bash
+   kubectl delete job -n monitoring -l job-name
+   
+   kubectl delete cronjob active-health-checks-nccl-tests-applier -n monitoring
+   ```
+