nginx.conf

# This file configures our nginx reverse proxy by specifying the desired behavior for incoming requests.
# In this case, we forward all incoming requests and its request headers to the chat-ui.

# Enable detailed logging for debugging purposes
error_log /var/log/nginx/error.log debug;

# Automatically determine the number of worker processes based on CPU cores
worker_processes auto;

events {
    # Set the maximum number of simultaneous connections each worker can handle
    worker_connections 1024;
}

http {
    # Define an upstream group for load balancing, even though we locally use one server
    upstream chat_ui_group {
        server chat-ui; # The hostname of the UI container, will be resolved by docker DNS
    }

    server {
        # Listen for HTTP traffic on port 80
        listen 80;

        # The location block defines what requests to forward and how. We forward everything.
        location / {
            # Forward requests to the upstream group
            proxy_pass http://chat_ui_group;

            # Preserve the original hostname in the Host header, required to work with Azure Container Apps
            proxy_set_header Host chat-ui;

            # Add the client’s IP address to the X-Forwarded-For header
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

            # Forward the original request protocol (HTTP/HTTPS)
            proxy_set_header X-Forwarded-Proto $scheme;

            # Forward the session cookie correctly
            proxy_set_header Cookie $http_cookie;

            # Use HTTP/1.1 for proxy connections, required to work with Azure if we want to run nginx manually
            proxy_http_version 1.1;
        }

        # Serve a static Nginx welcome page for health checks or debugging
        location /nginx {
            # Map this location to the default Nginx HTML directory
            alias /usr/share/nginx/html/;
            # Use index.html as the default file to serve
            index index.html;
        }
    }
}