Devops_best_practices
Chapter 96: DevOps and SysAdmin Best Practices
Section titled “Chapter 96: DevOps and SysAdmin Best Practices”Production System Administration Guidelines
Section titled “Production System Administration Guidelines”96.1 Automation Principles
Section titled “96.1 Automation Principles”Core Principles
Section titled “Core Principles” DevOps Principles+------------------------------------------------------------------+| || 1. Automate Everything || +----------------------------------------------------------+ || | • Manual processes are error-prone | || | • Scripts for all repetitive tasks | || | • Configuration management (Ansible, Puppet, Chef) | || +----------------------------------------------------------+ || || 2. Idempotent Configurations || +----------------------------------------------------------+ || | • Running multiple times produces same result | || | • Ansible: idempotent by design | || +----------------------------------------------------------+ || || 3. Infrastructure as Code || +----------------------------------------------------------+ || | • Version control infrastructure | || | • GitOps workflow | || | • Declarative definitions | || +----------------------------------------------------------+ || || 4. Immutable Infrastructure || +----------------------------------------------------------+ || | • Don't modify running systems | || | • Replace with new versions | || | • Containers, golden images | || +----------------------------------------------------------+ || |+------------------------------------------------------------------+96.2 Monitoring Best Practices
Section titled “96.2 Monitoring Best Practices”Key Metrics to Track
Section titled “Key Metrics to Track”# Infrastructure Metrics- CPU usage (per core, overall)- Memory usage (used, free, cached, swap)- Disk I/O (IOPS, throughput, latency)- Network (bandwidth, packets, errors)- Disk space usage
# Application Metrics- Request rate (RPM/RPS)- Response time (p50, p95, p99)- Error rate (5xx, exceptions)- Active connections- Queue depth
# Business Metrics- User signups- Transactions- Revenue- API callsAlerting Principles
Section titled “Alerting Principles” Alert Best Practices+------------------------------------------------------------------+| || 1. Signal-to-Noise Ratio || +----------------------------------------------------------+ || | • Only alert on actionable issues | || | • Avoid alert fatigue | || +----------------------------------------------------------+ || || 2. Severity Levels || +----------------------------------------------------------+ || | • Critical (immediate action) | || | • Warning (investigate soon) | || | • Info (no action needed) | || +----------------------------------------------------------+ || || 3. Runbooks || +----------------------------------------------------------+ || | • Document how to respond to each alert | || | • Include escalation paths | || +----------------------------------------------------------+ || |+------------------------------------------------------------------+96.3 Security Best Practices
Section titled “96.3 Security Best Practices”Defense in Depth
Section titled “Defense in Depth” Security Layers+------------------------------------------------------------------+| || 1. Network Security || +----------------------------------------------------------+ || | • Firewalls (host, network) | || | • Segmentation (VPCs, VLANs) | || | • WAF for web applications | || +----------------------------------------------------------+ || || 2. System Hardening || +----------------------------------------------------------+ || | • Principle of least privilege | || | • Regular patching and updates | || | • Disable unnecessary services | || +----------------------------------------------------------+ || || 3. Data Security || +----------------------------------------------------------+ || | • Encryption at rest | || | • Encryption in transit (TLS) | || | • Key management (secrets, vault) | || +----------------------------------------------------------+ || || 4. Monitoring and Response || +----------------------------------------------------------+ || | • Audit logging | || | • Intrusion detection | || | • Incident response plan | || +----------------------------------------------------------+ || |+------------------------------------------------------------------+96.4 Backup Best Practices
Section titled “96.4 Backup Best Practices”3-2-1 Rule
Section titled “3-2-1 Rule” Backup Strategy+------------------------------------------------------------------+| || 3 Copies of data || 2 Different storage types || 1 Offsite copy || || Testing: || +----------------------------------------------------------+ || | • Test restores regularly | || | • Document recovery procedures | || | • Automate recovery testing | || +----------------------------------------------------------+ || |+------------------------------------------------------------------+96.5 Documentation Standards
Section titled “96.5 Documentation Standards”What to Document
Section titled “What to Document”# System Documentation- Architecture diagrams- Network topology- IP addressing scheme- Service dependencies
# Runbooks- Deployment procedures- Troubleshooting guides- Emergency contacts- Rollback procedures
# Configuration- All configurations- Why changes were made- Approval records96.6 Interview Questions
Section titled “96.6 Interview Questions”Basic Questions
Section titled “Basic Questions”-
What is Infrastructure as Code?
- Managing infrastructure through code
-
What is the 3-2-1 backup rule?
- 3 copies, 2 media types, 1 offsite
-
What is principle of least privilege?
- Only minimum access needed
Summary
Section titled “Summary” Quick Reference+------------------------------------------------------------------+| || Key Principles: || +----------------------------------------------------------+ || | Automate everything | || | Monitor proactively | || | Security in depth | || | Test backups regularly | || | Document everything | || +----------------------------------------------------------+ || |+------------------------------------------------------------------+