Set and get environment variables

You can use the sandbox.env.set() method to set environment variables in a sandbox.

import { Sandbox } from "@deno/sandbox";

await using sandbox = await Sandbox.create();

// Set environment variables
await sandbox.env.set("API_KEY", "secret-key-123");
await sandbox.env.set("NODE_ENV", "production");

// Use them in a script
const apiKey = await sandbox.sh`echo $API_KEY`.text();
console.log("API_KEY:", apiKey.trim());

Setting environment variables through sandbox.env.set() keeps configuration and secrets inside the sandbox, so scripts run with the expected context without hardcoding values in source files. That’s helpful when you need per-run configuration (API keys, modes like NODE_ENV) or want to propagate credentials to multiple commands securely. The variables stay scoped to the sandbox session and are available to any command you execute there.