Add startup probe guidance to Kubernetes deployment docs

Startup Probes

If pods enter CrashLoopBackOff after deployment, the liveness probe may be failing before the application finishes starting.

Symptoms

• Pods cycle between Running and CrashLoopBackOff
• kubectl describe pod shows: "Liveness probe failed: HTTP probe failed with statuscode: 503"
• The app takes longer to start than the liveness probe's initialDelaySeconds

Solution

Add a startupProbe to your deployment spec:

startupProbe:
  httpGet:
    path: /healthz
    port: 8080
  failureThreshold: 30
  periodSeconds: 10

This allows up to 5 minutes for startup (30 failures × 10s interval). Once the startup probe succeeds, Kubernetes switches to the regular liveness probe.

When to use startupProbe vs initialDelaySeconds

• startupProbe: Preferred for apps with variable startup times. Kubernetes will not run liveness/readiness checks until the startup probe succeeds.
• initialDelaySeconds: Use when startup time is predictable and consistent. Simpler but less flexible — if startup takes longer than expected, the pod will be killed.