SSL Termination — Complete Gateway TLS Guide

In this tutorial, you will learn about SSL Termination. We cover key concepts, practical examples, and best practices to help you master this topic.

SSL termination is the Process of decrypting HTTPS traffic at the API Gateway so that backend services receive plain HTTP requests. This centralizes certificate management and reduces CPU overhead on backend services.

What You'll Learn

You'll learn SSL termination best practices, certificate management, and how to configure it in popular gateways.

Why It Matters

SSL termination reduces the number of TLS handshakes, centralizes certificate renewal, and allows backend services to communicate over faster HTTP internally.

Real-World Use

An API gateway terminates TLS for 50 Microservices. The DevOps team manages 3 certificates on the gateway instead of 50 certificates across all services. Backend services use HTTP, reducing their CPU usage by 30%.

Implementation

# NGINX SSL termination
server {
    listen 443 ssl http2;
    server_name api.example.com;

    ssl_certificate /etc/ssl/certs/api.example.com.crt;
    ssl_certificate_key /etc/ssl/certs/api.example.com.key;
    ssl_protocols TLSv1.2 TLSv1.3;
    ssl_ciphers HIGH:!aNULL:!MD5;
    ssl_prefer_server_ciphers on;
    ssl_session_cache shared:SSL:10m;
    ssl_session_timeout 10m;

    location / {
        proxy_pass http://backend-service:3000;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_set_header X-Forwarded-Ssl on;
    }
}

Common Mistakes

What's Next

Learn about request transformation in API gateways.