Runtime

Environment Variables

Environment variables allow you to configure your actors without changing code, enabling more flexible deployments.

Configuring Actor Behavior

Environment variables can be provided when creating an actor:

TypeScript

const actor = await client.actors.create({
  // ...
  network: {
    ports: {
      http: { protocol: "https" }
    }
  },
  runtime: {
    environment: { 
      GREETING: "Hello, world!" 
    }
  }
});

Example: Dynamic HTTP Server

Here's how you can use environment variables in your actor's code:

const express = require('express');
const app = express();

// Get the port from the environment variable
const port = process.env.PORT_HTTP;

// Get custom environment variable with fallback
const greeting = process.env.GREETING || "Hello, visitor!";

app.get('/', (req, res) => {
  res.send(greeting);
});

app.listen(port, () => {
  console.log(`Server running on port ${port}`);
});

By changing the GREETING environment variable, you can modify the server's response without changing code.

Default Environment Variables

Rivet provides the following default environment variables:

PORT_{NAME}: The port number assigned to a named port (e.g., PORT_HTTP for a port named "http")

For more details about networking and ports, see Networking.