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

1. Rotate logs to prevent disk fill
2. Structured logging (JSON) for parsing
3. Appropriate levels (error/warn/info/debug)
4. 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:

1. Check if running (process status)
2. Check logs (error messages)
3. Check resources (disk, memory, CPU)
4. Check network (ports, DNS)
5. 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.