whd4 Server Management
Server management principles for production operations. Learn to THINK, not memorize commands.
1. Process Management Principles
Tool Selection
| Scenario | Tool |
|---|---|
| Node.js app | PM2 (clustering, reload) |
| Any app | systemd (Linux native) |
| Containers | Docker/Podman |
| Orchestration | Kubernetes, Docker Swarm |
Process Management Goals
| Goal | What It Means |
|---|---|
| Restart on crash | Auto-recovery |
| Zero-downtime reload | No service interruption |
| Clustering | Use all CPU cores |
| Persistence | Survive server reboot |
2. Monitoring Principles
What to Monitor
| Category | Key Metrics |
|---|---|
| Availability | Uptime, health checks |
| Performance | Response time, throughput |
| Errors | Error rate, types |
| Resources | CPU, memory, disk |
Alert Severity Strategy
| Level | Response |
|---|---|
| Critical | Immediate action |
| Warning | Investigate soon |
| Info | Review daily |
Monitoring Tool Selection
| Need | Options |
|---|---|
| Simple/Free | PM2 metrics, htop |
| Full observability | Grafana, Datadog |
| Error tracking | Sentry |
| Uptime | UptimeRobot, Pingdom |
3. Log Management Principles
Log Strategy
| Log Type | Purpose |
|---|---|
| Application logs | Debug, audit |
| Access logs | Traffic analysis |
| Error logs | Issue detection |
Log Principles
- Rotate logs to prevent disk fill
- Structured logging (JSON) for parsing
- Appropriate levels (error/warn/info/debug)
- No sensitive data in logs
4. Scaling Decisions
When to Scale
| Symptom | Solution |
|---|---|
| High CPU | Add instances (horizontal) |
| High memory | Increase RAM or fix leak |
| Slow response | Profile first, then scale |
| Traffic spikes | Auto-scaling |
Scaling Strategy
| Type | When to Use |
|---|---|
| Vertical | Quick fix, single instance |
| Horizontal | Sustainable, distributed |
| Auto | Variable traffic |
5. Health Check Principles
What Constitutes Healthy
| Check | Meaning |
|---|---|
| HTTP 200 | Service responding |
| Database connected | Data accessible |
| Dependencies OK | External services reachable |
| Resources OK | CPU/memory not exhausted |
Health Check Implementation
- Simple: Just return 200
- Deep: Check all dependencies
- Choose based on load balancer needs
6. Security Principles
| Area | Principle |
|---|---|
| Access | SSH keys only, no passwords |
| Firewall | Only needed ports open |
| Updates | Regular security patches |
| Secrets | Environment vars, not files |
| Audit | Log access and changes |
7. Troubleshooting Priority
When something's wrong:
- Check if running (process status)
- Check logs (error messages)
- Check resources (disk, memory, CPU)
- Check network (ports, DNS)
- Check dependencies (database, APIs)
8. Anti-Patterns
| ❌ Don't | ✅ Do |
|---|---|
| Run as root | Use non-root user |
| Ignore logs | Set up log rotation |
| Skip monitoring | Monitor from day one |
| Manual restarts | Auto-restart config |
| No backups | Regular backup schedule |
Remember: A well-managed server is boring. That's the goal.