Bits of .NET

🔄 Pod Lifecycle Hooks

Pods have lifecycle events. Lifecycle hooks run at specific times. Init, pre-stop, post-start.

📝 Hook Types

apiVersion: v1
kind: Pod
metadata:
    name: app
spec:
    containers:
    - name: app
        image: myapp:latest
        lifecycle:
            postStart:
                exec:
                    command: ["/bin/sh", "-c", "echo 'Container started'"]
            preStop:
                exec:
                    command: ["/bin/sh", "-c", "echo 'Container stopping' && sleep 5"]

# postStart
- Runs after container starts
- For initialization
- Non-blocking

# preStop
- Runs before container stops
- Graceful shutdown
- Cleanup tasks

# HTTP Hook
lifecycle:
    postStart:
        httpGet:
            host: localhost
            path: /health
            port: 8080

🎯 Hook Examples

# Database migration postStart
lifecycle:
    postStart:
        exec:
            command: ["/bin/sh", "-c", "npm run migrate"]

# Graceful shutdown preStop
lifecycle:
    preStop:
        exec:
            command: ["/bin/sh", "-c", "npm run shutdown"]

# Wait for dependencies
lifecycle:
    postStart:
        exec:
            command: ["/bin/sh", "-c", "until nc -z database 5432; do sleep 2; done"]

# Cleanup preStop
lifecycle:
    preStop:
        exec:
            command: ["/bin/sh", "-c", "rm -rf /tmp/* && echo 'Cleaned up'"]

# Log backup preStop
lifecycle:
    preStop:
        exec:
            command: ["/bin/sh", "-c", "cp /app/logs/app.log /backup/ && echo 'Logs backed up'"]

# Hook with timeout
lifecycle:
    preStop:
        exec:
            command: ["/bin/sh", "-c", "sleep 30 && echo 'Shutdown complete'"]
    terminationGracePeriodSeconds: 60

# Hook Best Practices
- Use preStop for graceful shutdown
- Use postStart for initialization
- Set appropriate timeouts
- Test hooks thoroughly
- Handle hook failures

💡 Hook Tips

• Use preStop for graceful shutdown
• Use postStart for initialization
• Set appropriate timeouts
• Test hooks thoroughly
• Handle hook failures