Kubernetes Startup Probe Health Check

Kubernetes Startup Probe

Startup probes protect slow-starting applications from being killed by liveness probes before they finish initializing. The startup probe runs only during container startup and disables liveness and readiness probes until it succeeds.

Response Format

{
  "status": "ok",
  "started": true,
  "checks": {
    "databaseMigration": { "status": "completed" },
    "cacheWarmup": { "status": "completed" },
    "configLoaded": { "status": "completed" }
  }
}

During initialization:

{
  "status": "fail",
  "started": false,
  "checks": {
    "databaseMigration": { "status": "completed" },
    "cacheWarmup": { "status": "in_progress" },
    "configLoaded": { "status": "completed" }
  }
}

Probe Configuration

startupProbe:
  httpGet:
    path: /startup
    port: 8080
  initialDelaySeconds: 0
  periodSeconds: 5
  timeoutSeconds: 3
  failureThreshold: 30   # 30 * 5s = 150s max startup time

Common Startup Tasks

Task	Typical Duration	Impact
Database migrations	10-60s	Schema must be ready
Cache warmup	5-30s	Cold cache causes latency
Config loading	1-5s	App needs configuration
Connection pooling	2-10s	DB pool initialization
Service registration	1-3s	Service mesh enrollment

Why Use Startup Probes

Without startup probes, you must set initialDelaySeconds on liveness probes high enough for worst-case startup time. Startup probes decouple startup time from ongoing health checks, allowing tight liveness probe intervals while supporting slow starts.