Adding HTTPS with Caddy and DuckDNS

After deploying the application to EC2, it initially worked only through:

http://EC2-IP

The next step was understanding how HTTPS is normally added.

The Stack

I used:

• DuckDNS for a free test domain
• Caddy as a reverse proxy
• Let’s Encrypt certificates managed automatically by Caddy

Final setup:

https://dsuopd.duckdns.org

Architecture

Internet
   ↓
Caddy
   ↓
localhost:3000
   ↓
Docker app container

The application container itself is no longer publicly exposed directly.

Instead, Caddy:

• receives public traffic
• manages HTTPS certificates
• forwards requests internally

What Clicked

The biggest conceptual shift was understanding the role of a reverse proxy.

The browser does not communicate directly with the application container.

Instead:

Browser
   ↓
Reverse proxy
   ↓
Application

Caddy also automatically:

• requests certificates
• renews certificates
• redirects HTTP to HTTPS

which makes it extremely beginner-friendly for learning infrastructure.