{
  "id": "rootnode-probe-port-mismatch",
  "title": "Stuck Not-Ready: The Probe Port Mismatch",
  "category": "Observability & Ops",
  "difficulty": "Medium",
  "type": "task",
  "weight": 8,
  "description": "## Stuck Not-Ready: The Probe Port Mismatch\n\nA deployment named `api-gateway` was rolled out to the `default` namespace. The pods start, the container runs — but the deployment never reaches Ready. Traffic won't be routed to it, and the on-call alert is firing.\n\nThis is a class of incident that is easy to miss: the container is actually healthy, but Kubernetes disagrees because the readiness probe is checking the **wrong port**. In production this pattern silently blocks rollouts, causes zero-downtime deploys to stall, and is tricky to diagnose if you go straight to logs instead of reading events.\n\n**Your task:** Diagnose why the pods are failing their readiness check, correct the probe configuration, and restore the deployment to **2/2 Ready**.\n\n> Tip: start with pod status and events — the scheduler and kubelet leave a clear trail. Read before you patch.",
  "hints": [
    {
      "title": "1. See the failure",
      "body": "List pods and look at the READY column. Then describe one of the failing pods and read the Events section at the bottom — kubelet reports readiness probe failures there with the exact port it tried.",
      "command": "kubectl get pods\nkubectl describe pod -l app=api-gateway"
    },
    {
      "title": "2. Inspect the probe config",
      "body": "Pull the readiness probe definition from the live deployment. You are looking for the httpGet port — compare it to the port nginx actually listens on (80).",
      "command": "kubectl get deployment api-gateway -o jsonpath='{.spec.template.spec.containers[0].readinessProbe}'"
    },
    {
      "title": "3. Patch the probe port",
      "body": "Use a JSON patch to correct the readiness probe port to 80. The deployment will trigger a new rollout and the pods should become Ready within a few seconds.",
      "command": "kubectl patch deployment api-gateway --type='json' -p='[{\"op\":\"replace\",\"path\":\"/spec/template/spec/containers/0/readinessProbe/httpGet/port\",\"value\":80}]'"
    }
  ],
  "setup_commands": [
    { "command": "kubectl create deployment api-gateway --image=nginx:1.25 --replicas=2" },
    { "command": "kubectl patch deployment api-gateway --type='json' -p='[{\"op\":\"add\",\"path\":\"/spec/template/spec/containers/0/readinessProbe\",\"value\":{\"httpGet\":{\"path\":\"/\",\"port\":8080},\"initialDelaySeconds\":3,\"periodSeconds\":5}}]'" }
  ],
  "validation": {
    "description": "Checks that the probe port is corrected and both replicas are Ready.",
    "commands": [
      {
        "description": "Readiness probe port is 80",
        "command": "kubectl get deployment api-gateway -o jsonpath='{.spec.template.spec.containers[0].readinessProbe.httpGet.port}'",
        "expected_output": "80",
        "match": "exact"
      },
      {
        "description": "Deployment has 2 ready replicas",
        "command": "kubectl get deployment api-gateway -o jsonpath='{.status.readyReplicas}' 2>/dev/null | grep -v '^$' || echo 0",
        "expected_output": "2",
        "match": "exact"
      },
      {
        "description": "No pods stuck in non-Running state",
        "command": "kubectl get pods -l app=api-gateway --no-headers 2>/dev/null | awk '{print $3}' | grep -cv 'Running' || true",
        "expected_output": "0",
        "match": "exact"
      }
    ]
  },
  "default_namespace": "default",
  "teardown_commands": [
    { "command": "kubectl delete deployment api-gateway --ignore-not-found" }
  ]
}