DevOps: What is Kubernetes Pod Lifecycle Startup Probe?

1apiVersion: apps/v1
2kind: Deployment
3metadata:
4  name: myapp
5spec:
6  replicas: 3
7  template:
8    spec:
9      containers:
10      - name: app
11        image: myapp:latest
12        startupProbe:
13          httpGet:
14            path: /healthz
15            port: 8080
16          failureThreshold: 30
17          periodSeconds: 10
18          initialDelaySeconds: 5
19          timeoutSeconds: 3
20          successThreshold: 1
21        readinessProbe:
22          httpGet:
23            path: /ready
24            port: 8080
25          periodSeconds: 10
26          successThreshold: 1
27          failureThreshold: 3
28        livenessProbe:
29          httpGet:
30            path: /healthz
31            port: 8080
32          periodSeconds: 20
33          successThreshold: 1
34          failureThreshold: 3
35---
36# TCP startup probe
37apiVersion: apps/v1
38kind: Deployment
39metadata:
40  name: myapp-tcp
41spec:
42  template:
43    spec:
44      containers:
45      - name: app
46        image: myapp:latest
47        startupProbe:
48          tcpSocket:
49            port: 8080
50          failureThreshold: 30
51          periodSeconds: 10
52---
53# Exec startup probe
54apiVersion: apps/v1
55kind: Deployment
56metadata:
57  name: myapp-exec
58spec:
59  template:
60    spec:
61      containers:
62      - name: app
63        image: myapp:latest
64        startupProbe:
65          exec:
66            command:
67            - sh
68            - -c
69            - "cat /tmp/started"
70          failureThreshold: 30
71          periodSeconds: 10

1# Check startup probe
2kubectl describe pod my-pod | grep -A 10 "startupProbe"
3
4# Check probe status
5kubectl get pod my-pod -o jsonpath='{.status.conditions}' | jq
6
7# View startup logs
8kubectl logs my-pod --previous
9
10# Check container ready state
11kubectl get pod my-pod -o jsonpath='{.status.containerStatuses[0].ready}'
12
13# Verify startup probe passed
14kubectl get pod my-pod -o jsonpath='{.status.containerStatuses[0].started}'