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Overview

The server configuration controls how the MTB Backend API listens for incoming requests and manages application security. Configuration is defined in config/server.ts and controlled through environment variables.

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Server Settings

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Host and Port

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HOST
string
default:"0.0.0.0"
The hostname or IP address the server will bind to. Use 0.0.0.0 to listen on all network interfaces, or 127.0.0.1 for localhost only.
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PORT
integer
default:"1337"
The port number the server will listen on for HTTP requests.
# Listen on localhost only
HOST=127.0.0.1
PORT=1337
In production environments, it’s common to use 0.0.0.0 as the host to allow the server to accept connections from any network interface. A reverse proxy like NGINX typically handles external traffic.

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Application Keys

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Security Keys

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APP_KEYS
array
required
Array of secret keys used for signing and encrypting sessions, cookies, and other security-sensitive data. Required for production deployments.
Application keys are critical for security. Never commit them to version control or share them publicly. Generate strong, random keys for production environments.

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Generating App Keys

App keys should be long, random strings. You can generate them using various methods: 
# Generate a random key using OpenSSL
openssl rand -base64 32

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Setting App Keys

Provide multiple keys as a comma-separated list in your .env file:
.env
APP_KEYS=key1base64encoded==,key2base64encoded==,key3base64encoded==,key4base64encoded==
Multiple keys enable key rotation. The first key is used for signing new data, while the others are used to validate existing signatures during rotation periods.

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Configuration Example

export default ({ env }) => ({
  host: env('HOST', '0.0.0.0'),
  port: env.int('PORT', 1337),
  app: {
    keys: env.array('APP_KEYS'),
  },
});

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Environment-Specific Configuration

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Development

For local development:
.env
HOST=127.0.0.1
PORT=1337
APP_KEYS=developmentKeyOnly==

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Staging

For staging environments:
.env
HOST=0.0.0.0
PORT=1337
APP_KEYS=stagingKey1==,stagingKey2==,stagingKey3==,stagingKey4==

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Production

For production deployments:
.env
HOST=0.0.0.0
PORT=1337
APP_KEYS=prodKey1==,prodKey2==,prodKey3==,prodKey4==
Always use different application keys for each environment. Never reuse development keys in production.

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Deployment Considerations

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Reverse Proxy Setup

When deploying behind a reverse proxy (NGINX, Apache, etc.):
.env
# Server listens on internal network interface
HOST=0.0.0.0
PORT=1337
Your reverse proxy configuration should forward requests to localhost:1337.

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Container Deployment

For Docker or containerized deployments:
.env
# Listen on all interfaces inside the container
HOST=0.0.0.0
PORT=1337
Map the container port to your host:
Docker
docker run -p 80:1337 -e HOST=0.0.0.0 -e PORT=1337 your-image

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Port Binding

Ports below 1024 typically require root privileges on Unix-like systems. Consider using a reverse proxy or port forwarding instead of binding directly to ports like 80 or 443.

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Troubleshooting

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Server Won’t Start

If the server fails to start:
  1. Check if the port is already in use: 
    lsof -i :1337
  2. Verify APP_KEYS is set: 
    echo $APP_KEYS
  3. Check host binding permissions:
    • Use 127.0.0.1 for localhost testing
    • Ensure you have permission to bind to the specified interface

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Cannot Connect to Server

If you cannot connect to the server:
  1. Verify the server is running: 
    curl http://localhost:1337
  2. Check firewall rules:
    • Ensure the port is not blocked
    • Verify network security groups (cloud deployments)
  3. Confirm host binding:
    • 127.0.0.1 only accepts localhost connections
    • 0.0.0.0 accepts connections from any interface

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