Vercel Eve

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Why E2B as the backend

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Prerequisites

• Node.js 22 or later
• An Eve project (npx eve@latest init my-agent)
• An E2B API key

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Install

npm i @e2b/eve-sandbox e2b

export E2B_API_KEY="e2b_***"

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Configure the backend

import { defineSandbox } from 'eve/sandbox'
import { e2b } from '@e2b/eve-sandbox'

export default defineSandbox({
  backend: () => e2b({ template: 'base' }),
})

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Run the agent

pnpm dev        # or: npx eve dev

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Bootstrap and per-session setup

import { defineSandbox } from 'eve/sandbox'
import { e2b } from '@e2b/eve-sandbox'

export default defineSandbox({
  backend: () =>
    e2b({
      template: 'base',
      timeoutMs: 30 * 60 * 1000,
      envs: { NODE_ENV: 'production' },
    }),

  // Build time, once per template — baked into a reusable E2B snapshot.
  async bootstrap({ use }) {
    const sandbox = await use()
    await sandbox.run({ command: 'sudo apt-get install -y jq' })
  },

  // Once per durable session — tighten egress for the turn.
  async onSession({ use }) {
    await use({ networkPolicy: { allow: ['*.npmjs.org', 'github.com'] } })
  },
})

• bootstrap runs during Eve’s build-time prewarm(). The backend creates a sandbox, runs your bootstrap, writes your workspace/ seed files, then captures an E2B snapshot. Later sessions fork that snapshot, so installs are paid once, not per session.
• onSession runs once per durable session against a live sandbox, and is the right place for network policy, per-user credentials, and one-time markers.

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Session persistence

1. The sandboxId persisted by Eve for that session.
2. A still-running or paused sandbox whose E2B metadata matches eveBackend: "e2b" and the session’s eveSessionKey.
3. Otherwise a fresh sandbox, forked from the prewarmed snapshot.

• The backend’s shutdown() is intentionally a no-op. Killing the sandbox on server shutdown would drop background work and force Eve to recreate it without rerunning onSession. Sandboxes are left paused and expire on their own — kill them from the dashboard or the SDK if you want them gone sooner. Opt out with autoPause: false to kill on timeout instead.
• Reconnects do not re-apply the configured networkPolicy. A resumed sandbox keeps its live policy, including any tightening onSession applied. Re-stamping the create-time default could silently loosen a locked-down session.

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Network policy

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Credential brokering

async onSession({ use }) {
  await use({
    networkPolicy: {
      allow: {
        'github.com': [{ transform: [{ headers: { authorization: 'Basic your_base64_credentials_here' } }] }],
        'api.example.com': [],
      },
    },
  })
}

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Custom templates

export default defineSandbox({
  backend: () => e2b({ template: 'your-template-id-or-name' }),
})

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Backend options

e2b({
  template: 'base',                  // E2B template ID or alias
  timeoutMs: 30 * 60 * 1000,         // auto-pause timeout; default 30 minutes
  envs: { NODE_ENV: 'production' },  // env vars baked into every sandbox
  metadata: { team: 'growth' },      // E2B metadata, create-time only
  tags: { tier: 'beta' },            // diagnostic tags, merged into metadata
  apiKey: process.env.E2B_API_KEY,   // defaults to E2B_API_KEY
  domain: 'e2b.dev',                 // self-hosted or region endpoint
  networkPolicy: 'allow-all',        // initial policy for each fresh session
  autoPause: true,                   // false → kill on timeout instead of pause
  createOptions: {},                 // raw E2B SandboxOpts escape hatch
})

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How the integration works

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Learn more

• @e2b/eve-sandbox on GitHub — source, unit tests, and a runnable Next.js example
• Eve sandbox documentation — session handle API, lifecycle hooks, and backends
• Eve on Vercel — how Eve maps onto Vercel Functions, Workflows, and AI Gateway

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