16. Automated SSH Deployments: Self-Hosted Runners, Deploy Keys & Zero-Downtime Atomic Symlinks • DevOps, Docker & Cloud VPS Deployment Mastery • Rishabh Ki Kaksha

DevOps, Docker & Cloud VPS Deployment Mastery › 16. Automated SSH Deployments: Self-Hosted Runners, Deploy Keys & Zero-Downtime Atomic Symlinks

50 mins

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Course Syllabus

Module 1: Linux System Administration & Kernel Performance Tuning

01. Linux OS Architecture: Kernel vs User Space, System Calls & Process Management (ps, top, htop) 02. Linux File Permissions (chmod, chown, SUID/SGID) & Sticky Bits Security 03. Networking & Diagnostics: netstat, ss, lsof, tcpdump, curl, dig & DNS Resolution

Part 1: Linux & Docker Containerization

Module 2: Containerization with Docker & Multi-Stage Builds

04. Docker Architecture: Namespaces, Cgroups, UnionFS & Docker Engine Internals 05. Dockerfile Optimization: Layer Caching, Non-Root Users & Ultra-Light Alpine Multi-Stage Builds 06. Docker Compose: Multi-Container Networking, Persistent Volumes & Environment Config 07. Docker Production Security: Read-Only Root FS, Capabilities Drop & Container Scanning

Part 2: Nginx, SSL, PM2 & Automated CI/CD

Module 3: Nginx Reverse Proxy, SSL Automation & Security Hardening

08. Nginx Masterclass: Event-Driven Non-Blocking Architecture vs Apache Multi-Threaded 09. Nginx as Reverse Proxy, Load Balancer (upstream) & Gzip/Brotli Compression Config 10. SSL/TLS Automation with Certbot Let's Encrypt, HTTP/2 & Strict-Transport-Security (HSTS) 11. Nginx Rate Limiting (limit_req), DDoS Mitigation & Security Headers Injection

Module 4: Process Management with PM2 & Systemd Services

12. Systemd Services: Creating Custom System Daemons with Automatic Restart & Logging 13. PM2 Enterprise Process Manager: Cluster Mode, Ecosystem Config & Graceful Reloads 14. Log Management & Rotation: logrotate, journalctl & Centralized Syslog Streaming

Module 5: CI/CD Automation with GitHub Actions & Zero-Downtime Deployments

15. CI/CD Foundations: Building Automated Test & Build Pipelines with GitHub Actions 16. Automated SSH Deployments: Self-Hosted Runners, Deploy Keys & Zero-Downtime Atomic Symlinks 17. Blue-Green & Canary Deployment Strategies on Cloud VPS Infrastructure

Module 6: Cloud VPS Production Hardening, Firewall (UFW) & Backups

18. Cloud VPS Hardening: Non-Root Sudo Users, SSH Key-Only Auth, Fail2ban & UFW Firewall Rules 19. Automated Database & Media Backups to Cloud Storage (AWS S3 / Cloudflare R2 / MinIO) 20. Server Health Monitoring & Alerting: Uptime Kuma, Netdata, Prometheus & Telegram Bot Webhooks

Interactive Lesson Studio

# 16. Automated SSH Deployments: Self-Hosted Runners, Deploy Keys & Zero-Downtime Atomic Symlinks

> DevOps & Cloud VPS Notes by Rishabh - Topic 16

---

### 1. Atomic Symlink Deployment Architecture (Capistrano / Deployer Style 🔗)

Live directory me direct `git pull` karne se users ko 5 seconds ke liye broken partial files mil sakti hain.  
**Atomic Symlink Deployment:** Naya release alag folder me build karo aur **Linux atomic `ln -nfs` switch** execute karo!

```
/var/www/app/
 ├── releases/
 │    ├── 20260821_0100/  (Old Release)
 │    └── 20260822_0125/  (New Live Release!)
 └── current ──────(Atomic Symlink)─────► releases/20260822_0125/
```

```bash
# Instant Atomic Switch (0.001ms):
ln -nfs /var/www/app/releases/20260822_0125 /var/www/app/current
```

---

### 2. Interview Ke 3 Sawal Is Topic Se

1. **Linux `ln -nfs` atomic kyu hota hai?** -> Kyunki ye single kernel inode update operation hota hai; traffic instantly naye folder par shift hota hai bina broken intermediate state ke.
2. **Deploy Keys vs Personal Access Tokens me kya advantage hai?** -> Deploy Key specific single repository ke liye read-only SSH key hoti hai; developer ke personal account access se completely isolated hoti hai.
3. **Instant 1-Click Rollback kaise hota hai?** -> Sirf purane release directory ka symlink point karke `pm2 reload` chalana (Instant recovery in < 1 second).

---
**Next Topic:** 17. Blue-Green & Canary Deployment Strategies on Cloud VPS Infrastructure

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Rishabh Gehlot

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