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E2B provides Firecracker microVMs — full Linux sandboxes with sub-second cold starts (in the same region), persistent disk during their lifetime, and built-in Python and Node.js support. They’re designed for fast, ephemeral code execution.

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Install the connector

Run flue add e2b and pipe it to your coding agent. The agent reads the connector instructions and writes .flue/connectors/e2b.ts into your project. 
flue add e2b | claude
flue add e2b | opencode
flue add e2b | codex
flue add e2b | cursor-agent
The agent also installs e2b if it isn’t already in your package.json.

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Set up your API key

You need E2B_API_KEY at runtime. Get one from the E2B dashboard. Add it to your .env file, CI secrets, or equivalent: 
# .env
E2B_API_KEY="your-api-key"
The e2b SDK reads E2B_API_KEY from the environment automatically — you don’t pass it explicitly when creating a sandbox. Pass the file to Flue’s dev server or run command: 
flue dev --target node --env .env
flue run my-agent --target node --env .env

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Basic usage

After the connector is installed, create an E2B sandbox and pass it to init(): 
import type { FlueContext } from '@flue/runtime';
import { Sandbox } from 'e2b';
import { e2b } from '../connectors/e2b';

export const triggers = { webhook: true };

export default async function ({ init }: FlueContext) {
  // E2B reads E2B_API_KEY from the environment automatically.
  const sandbox = await Sandbox.create();

  const harness = await init({
    sandbox: e2b(sandbox),
    model: 'anthropic/claude-sonnet-4-6',
  });
  const session = await harness.session();

  return await session.shell('uname -a');
}
You own the sandbox lifecycle. Flue does not close or delete it — you decide when the sandbox’s session ends.

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Custom templates

E2B supports custom templates — pre-built snapshots with your tools already installed. If you run many short-lived agents against the same prepared environment, a custom template avoids reinstalling tooling on every cold start: 
const sandbox = await Sandbox.create('my-template-name');
Create and manage templates from the E2B dashboard or CLI. See E2B’s templates documentation for details.

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Code interpreter variant

If you’re building a Jupyter-style code interpreter agent, E2B also publishes @e2b/code-interpreter, which re-exports the same Sandbox class with extra runCode methods. The connector works with it too — install @e2b/code-interpreter instead of e2b and adjust the import in the connector file: 
import type { Sandbox as E2BSandbox } from '@e2b/code-interpreter';

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When to use E2B

E2B works from any Flue deployment target — Node.js, Cloudflare, GitHub Actions. It’s the right choice when your agent needs:
  • Fast ephemeral sandboxes with sub-second cold starts
  • Python or Node.js environments without complex setup
  • Short-lived code execution without persistent state across requests
For agents that need a full coding environment with git, a cloned repo, or declarative image builds, consider Daytona. For agents running on Cloudflare, see the Cloudflare connector.

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Resources

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