sandbox

---
name: sandbox
description: Creates isolated Linux MicroVMs using Vercel Sandbox SDK. Use when building code execution environments, running untrusted code, spinning up dev servers, testing in isolation, or when the user mentions "sandbox", "microvm", "isolated execution", or "@vercel/sandbox".
license: Apache-2.0
---

## _CRITICAL_: Always Use Correct `@vercel/sandbox` Documentation

Your knowledge of `@vercel/sandbox` may be outdated.
Follow these instructions before starting on any sandbox-related tasks:

### Official Resources

- **Documentation**: https://vercel.com/docs/vercel-sandbox
- **SDK Reference**: https://vercel.com/docs/vercel-sandbox/sdk-reference
- **CLI Reference**: https://vercel.com/docs/vercel-sandbox/cli-reference
- **GitHub**: https://github.com/vercel/sandbox
- **REST API**: https://vercel.com/docs/rest-api/sandboxes

### What changed in v2

The `@vercel/sandbox@2` SDK and `sandbox@3` CLI replace anonymous, ephemeral
sandboxes with **named, persistent** sandboxes. Key differences from v1:

- Sandboxes are identified by **`name`** (not `sandboxId`). Names are unique per project.
- Sandboxes are **persistent by default** — when a sandbox stops, the SDK
  automatically snapshots it and restores the filesystem on the next resume.
- A **Session** is a single running VM instance inside a sandbox. SDK calls
  like `runCommand`, `writeFiles`, etc. automatically resume a stopped sandbox.
- New methods: `Sandbox.getOrCreate`, `Sandbox.fork`, `sandbox.update`,
  `sandbox.delete`, `sandbox.listSessions`, `sandbox.listSnapshots`,
  `Snapshot.tree`, `defineSandboxProxy`.
- New params: `name`, `persistent`, `tags`, `onResume`, `snapshotExpiration`,
  `keepLastSnapshots`, L7 network policy matchers, `forwardURL`.
- Pagination uses **cursor-based** iterators (async-iterable) instead of `since`/`until`.
- `Sandbox.list({ since, until })` → `Sandbox.list({ cursor, namePrefix, sortBy, tags })`.
- v1 sandboxes are backfilled so the only required code change is using `name`
  instead of `sandboxId`.

### Quick Reference

**Essential imports:**

```typescript
// Core SDK
import {
  Sandbox,
  Session,
  Snapshot,
  Command,
  CommandFinished,
} from "@vercel/sandbox";
import { APIError, StreamError } from "@vercel/sandbox";

// For advanced network policy with credential brokering and L7 matchers
import type {
  NetworkPolicy,
  NetworkPolicyRule,
  NetworkTransformer,
} from "@vercel/sandbox";

// For implementing a request-forwarding proxy (forwardURL)
import { defineSandboxProxy } from "@vercel/sandbox/proxy";

// For timeouts
import ms from "ms"; // e.g., ms("5m"), ms("1h")
```

**Default image:** Sandboxes use `vercel/sandbox/universal:latest`, an
Ubuntu-based image with Node.js 24, Bun, Python 3.14, coding agents, and common
development and debugging utilities.

## Creating Sandboxes

### Basic Creation

```typescript
import { Sandbox } from "@vercel/sandbox";

const sandbox = await Sandbox.create({
  name: "my-dev-env", // Optional, random if omitted. Unique per project.
  resources: { vcpus: 4 }, // 2048 MB RAM per vCPU
  ports: [3000], // Expose up to 15 ports
  timeout: ms("10m"), // Default: 5 minutes
  env: { NODE_ENV: "production" }, // Env vars inherited by all commands
  tags: { env: "staging", team: "infra" }, // Up to 5 key:value tags
  persistent: true, // Default: true. Auto-snapshots on stop, restores on resume.
  snapshotExpiration: ms("7d"), // Default TTL for snapshots. Use 0 for no expiration.
  region: "<region>", // Optional, defaults to iad1. See the Vercel docs for available regions.
  failoverRegions: ["<region>"], // Optional. Must not include `region`.
});

console.log(sandbox.name);
```

### Retrieve an Existing Sandbox

```typescript
// Retrieve by name. The sandbox will resume automatically the next time
// you run a command.
const sandbox = await Sandbox.get({ name: "my-dev-env" });
```

### Get-or-Create (Idempotent)

`Sandbox.getOrCreate` is the recommended pattern for long-lived sandboxes.

```typescript
const sandbox = await Sandbox.getOrCreate({
  name: "my-workspace",
  // Runs only the first time the sandbox is created.
  onCreate: async (sbx) => {
    await sbx.writeFiles([
      { path: "README.md", content: Buffer.from("# Hello") },
    ]);
    await sbx.runCommand("npm", ["install"]);
  },
  // Runs every time the sandbox session is resumed (including after auto-resume).
  onResume: async (sbx) => {
    await sbx.runCommand({ cmd: "npm", args: ["run", "dev"], detached: true });
  },
});
```

Behavior:

- If a sandbox with that `name` exists → resumes it and fires `onResume`.
- If it does not exist → creates a fresh sandbox and fires `onCreate`.
- If the sandbox exists but its snapshot expired → deletes the stale sandbox,
  re-creates it with the same name, and fires `onCreate`.

### Re-warming on Resume

Use `onResume` to restart background services or rehydrate caches whenever a
persistent sandbox's session is resumed:

```typescript
const sandbox = await Sandbox.get({
  name: "my-workspace",
  onResume: async (sbx) => {
    await sbx.runCommand({ cmd: "npm", args: ["run", "dev"], detached: true });
  },
});
```

`onResume` also fires when a SDK call (e.g. `runCommand`, `writeFiles`)
auto-resumes a stopped sandbox.

### With Git Source

```typescript
const sandbox = await Sandbox.create({
  source: {
    type: "git",
    url: "https://github.com/vercel/sandbox-example-next.git",
    depth: 1, // Shallow clone (optional)
    revision: "main", // Branch, tag, or commit (optional)
  },
  ports: [3000],
});
```

Git sources are cloned into a subdirectory named after the repository. For the
example above, run commands with `cwd: "sandbox-example-next"`.

### With Private Git Repository

```typescript
const sandbox = await Sandbox.create({
  source: {
    type: "git",
    url: "https://github.com/org/private-repo.git",
    username: process.env.GIT_USERNAME!,
    password: process.env.GIT_TOKEN!, // Use PAT for password
  },
});
```

### From Tarball

```typescript
const sandbox = await Sandbox.create({
  source: {
    type: "tarball",
    url: "https://example.com/project.tar.gz",
  },
  ports: [3000],
});
```

### From a Snapshot

```typescript
const sandbox = await Sandbox.create({
  source: {
    type: "snapshot",
    snapshotId: "snap_abc123",
  },
  ports: [3000],
});
```

### From a Custom Image (VCR)

Override the default with a [Vercel Container
Registry](https://vercel.com/docs/container-registry) (VCR) image stored in the
sandbox's project.

For a different distro or reproducible system tooling, prefer baking it into a
custom image over installing packages when the sandbox starts.

```typescript
const sandbox = await Sandbox.create({
  image: "my-repo:v1",
  ports: [3000],
});
```

`image` accepts a repository in the sandbox's project with an optional tag or
digest, or a fully-qualified VCR URL. A bare repository name resolves to the
`latest` tag:

```typescript
await Sandbox.create({ image: "my-repo" }); // latest tag
await Sandbox.create({ image: "my-repo:v1" }); // specific tag
await Sandbox.create({ image: "my-repo@sha256:..." }); // specific digest
await Sandbox.create({
  image: "vcr.vercel.com/my-team/my-project/my-repo:v1", // fully-qualified
});
```

Push images to VCR with Docker-compatible tooling before referencing them. See the
[Container Registry docs](https://vercel.com/docs/container-registry) for push
instructions.

### Forking an Existing Sandbox

`Sandbox.fork` seeds a new sandbox from another sandbox's current snapshot
and copies its config (`resources`, `timeout`, `networkPolicy`, `tags`,
`ports`, `image`, `persistent`, `snapshotExpiration`, `keepLastSnapshots`,
and `env`). Any field you pass overrides the inherited value. If the source
has no current snapshot, the fork falls back to the source's base environment
plus the copied config. You can only fork a sandbox in a project you have
access to; forking an unknown source returns a 404. The fork runs in the
source's region unless you pass `region` (and optionally `failoverRegions`)
to override it.

```typescript
// Inherit everything from the source (env included)
const fork = await Sandbox.fork({ sourceSandbox: "prod-agent" });

// Override specific fields; the rest are copied from the source.
// A provided `env` fully replaces the source's env (no per-key merge).
const fork = await Sandbox.fork({
  sourceSandbox: "prod-agent",
  name: "forked-prod-agent",
  resources: { vcpus: 4 },
  env: { OPENAI_API_KEY: process.env.OPENAI_API_KEY! },
});
```

### Auto-Dispose Pattern

Use `await using` for automatic cleanup:

```typescript
async function runInSandbox() {
  await using sandbox = await Sandbox.create();
  // Sandbox automatically stopped when scope exits
  await sandbox.runCommand("echo", ["Hello"]);
}
```

## Running Commands

### Basic Command Execution

```typescript
const result = await sandbox.runCommand("npm", ["install"]);
if (result.exitCode !== 0) {
  console.error("Install failed:", await result.stderr());
}
```

### With Options

```typescript
const result = await sandbox.runCommand({
  cmd: "npm",
  args: ["run", "build"],
  cwd: "/vercel/sandbox/app",
  env: { NODE_ENV: "production" },
  sudo: false,
  stdout: process.stdout, // Stream output
  stderr: process.stderr,
});
```

### Detached Commands (Background Processes)

```typescript
// Start dev server in background
const devServer = await sandbox.runCommand({
  cmd: "npm",
  args: ["run", "dev"],
  detached: true, // Returns immediately
  stdout: process.stdout,
});

// Later: wait for completion or kill
const finished = await devServer.wait();
// Supported signals: SIGHUP, SIGINT, SIGQUIT, SIGKILL, SIGTERM, SIGCONT, SIGSTOP (or numeric)
await devServer.kill("SIGTERM");
```

### Root Access

```typescript
await sandbox.runCommand({
  cmd: "apt-get",
  args: ["update"],
  sudo: true,
});
await sandbox.runCommand({
  cmd: "apt-get",
  args: ["install", "-y", "golang-go"],
  sudo: true, // Execute as root
});
```

## File Operations

### Write Files

```typescript
await sandbox.writeFiles([
  {
    path: "/vercel/sandbox/config.json",
    content: Buffer.from(JSON.stringify({ key: "value" })),
  },
  {
    path: "/vercel/sandbox/script.sh",
    content: Buffer.from("#!/bin/bash\necho 'Hello'"),
    mode: 0o755,
  },
]);
```

### Read Files

```typescript
// Returns a Buffer object
const buffer = await sandbox.readFileToBuffer({
  path: "/vercel/sandbox/output.txt",
});

// Returns a NodeJS.ReadableStream
const stream = await sandbox.readFile({
  path: "/vercel/sandbox/large-file.bin",
});
```

### Download Files

```typescript
const localPath = await sandbox.downloadFile(
  { path: "/vercel/sandbox/report.pdf" }, // source path on the sandbox
  { path: "./downloads/report.pdf" }, // destination path on the local machine
  { mkdirRecursive: true },
);
```

### Create Directories

```typescript
await sandbox.mkDir("/vercel/sandbox/my-app/src");
```

### `sandbox.fs` — `node:fs/promises`-compatible API

```typescript
const content = await sandbox.fs.readFile("/etc/hostname", "utf8");
await sandbox.fs.writeFile("/tmp/hello.txt", "Hello, world!");
const files = await sandbox.fs.readdir("/tmp");
const stats = await sandbox.fs.stat("/tmp/hello.txt");
```

## Multi-User and Groups

Create isolated Linux users and shared groups inside a sandbox. This is purely
SDK-side and is useful for isolating multiple agents or workloads within a single
sandbox. Usernames and group names are validated to prevent command injection.

### Creating Users

`createUser` provisions a Linux user with an isolated home directory at
`/home/<username>` and returns a `SandboxUser` whose operations run in that
user's context.

```typescript
const alice = await sandbox.createUser("alice");
alice.username; // "alice"
alice.homeDir; // "/home/alice"

// Commands run as alice; cwd defaults to /home/alice
const whoami = await alice.runCommand("whoami");
await whoami.stdout(); // "alice\n"

// Env vars, custom cwd, sudo escalation, and detached mode all work
await alice.runCommand({
  cmd: "node",
  args: ["-e", "console.log(process.env.SECRET)"],
  env: { SECRET: "hunter2" },
});
await alice.runCommand({
  cmd: "apt-get",
  args: ["update"],
  sudo: true,
});
await alice.runCommand({
  cmd: "apt-get",
  args: ["install", "-y", "git"],
  sudo: true,
});
const server = await alice.runCommand({
  cmd: "node",
  args: ["server.js"],
  detached: true,
});
```

Get a handle to a pre-existing user (e.g. `root`) without creating it:

```typescript
const existing = sandbox.asUser("bob");
await existing.runCommand("whoami");
```

### File Operations Scoped to a User

Relative paths resolve against the user's home directory and files are owned by
that user. Absolute paths are also supported.

```typescript
// Written to /home/alice, owned by alice:alice
await alice.writeFiles([
  { path: "app.js", content: Buffer.from('console.log("hi")') },
  { path: "data/config.json", content: Buffer.from("{}") },
]);

const buf = await alice.readFileToBuffer({ path: "app.js" });
const stream = await alice.readFile({ path: "app.js" });
await alice.mkDir("projects/my-app");
```

Files are isolated between users — one user cannot read, list, or write another
user's home directory (commands return a non-zero exit code with "Permission
denied").

### Groups and Shared Directories

`createGroup` creates a Linux group with a shared directory at
`/shared/<groupname>` (setgid `2770`), so files created inside it automatically
inherit group ownership. Group members can read and write there; non-members
are blocked.

```typescript
const devs = await sandbox.createGroup("devs");
devs.sharedDir; // "/shared/devs"

await sandbox.addUserToGroup("alice", "devs");
await sandbox.addUserToGroup("bob", "devs");

// Or via convenience methods on SandboxUser
await alice.addToGroup("devs");
await alice.removeFromGroup("devs");

await sandbox.removeUserFromGroup("alice", "devs");
```

## Network Policy

### Full Internet Access (Default)

```typescript
const sandbox = await Sandbox.create({
  networkPolicy: "allow-all",
});
```

### No Network Access

```typescript
const sandbox = await Sandbox.create({
  networkPolicy: "deny-all",
});
```

### Restricted Access (Simple Domain List)

```typescript
const sandbox = await Sandbox.create({
  networkPolicy: {
    allow: ["*.npmjs.org", "github.com", "registry.yarnpkg.com"],
    subnets: {
      allow: ["10.0.0.0/8"],
      deny: ["10.1.0.0/16"], // Takes precedence over allowed
    },
  },
});
```

### Restricted Access with Credential Brokering

```typescript
const sandbox = await Sandbox.create({
  networkPolicy: {
    allow: {
      "ai-gateway.vercel.sh": [
        {
          transform: [
            {
              headers: { authorization: "Bearer ..." },
            },
          ],
        },
      ],
      "*": [], // Allow all other domains without transforms
    },
  },
});
```

### L7 Request Matchers

Rules can match on method, path, query string, and headers. All specified
dimensions must match; multiple methods are ORed; multiple header and
query-string matchers are ANDed.

```typescript
const sandbox = await Sandbox.create({
  networkPolicy: {
    allow: {
      "ai-gateway.vercel.sh": [
        {
          match: {
            method: ["POST"],
            path: { startsWith: "/v1/" },
            headers: [
              { key: { exact: "x-api-key" }, value: { exact: "placeholder" } },
            ],
          },
          transform: [{ headers: { authorization: "Bearer ..." } }],
        },
      ],
    },
  },
});
```

Matchers support `exact`, `startsWith`, and `regex` (RE2).

### Forward Matching Requests to a Proxy

Use `forwardURL` to redirect any matching request through an HTTPS proxy you
control. The proxy receives the original request along with sandbox metadata in
forwarded headers.

```typescript
const sandbox = await Sandbox.create({
  networkPolicy: {
    allow: {
      "api.example.com": [
        {
          match: { path: { startsWith: "/secure/" } },
          forwardURL: "https://my-proxy.example.com",
        },
      ],
    },
  },
});
```

Implement the proxy handler with `defineSandboxProxy`, using the Web `Request` & `Response` objects — it verifies the
sandbox OIDC token and extracts metadata about the source sandbox:

```typescript
// app/api/sandbox-proxy/route.ts
import { defineSandboxProxy } from "@vercel/sandbox/proxy";

const handler = defineSandboxProxy(async (request, meta) => {
  // meta: { host, teamId, projectId, sandboxId, sandboxName }
  console.log("Proxied from sandbox", meta.sandboxName);
  return fetch(request);
});

// Sandboxes forward requests using their original method, so the handler
// must be exposed under every verb the network policy can route.
export {
  handler as GET,
  handler as POST,
  handler as PUT,
  handler as PATCH,
  handler as DELETE,
};
```

### Updating Network Policy at Runtime

Use `sandbox.update` (preferred). `updateNetworkPolicy` is deprecated but still
works.

```typescript
await sandbox.update({ networkPolicy: { allow: ["api.openai.com"] } });
```

## Updating Sandbox Configuration

`sandbox.update` replaces individual update helpers and accepts any of the
mutable parameters. When `ports` is provided, it is treated as the **full**
desired port list — any currently exposed port not present in the array is
deregistered.

```typescript
await sandbox.update({
  resources: { vcpus: 4 }, // Memory auto-scales to 2048 MB per vCPU
  timeout: ms("30m"),
  networkPolicy: "deny-all",
  ports: [3000, 8000],
  tags: { env: "prod" },
  persistent: false,
  snapshotExpiration: ms("14d"),
  keepLastSnapshots: { count: 1 },
  currentSnapshotId: "snap_xyz", // Rollback to a previous snapshot
  region: "sfo1", // Applies to the next session
  failoverRegions: ["cle1"], // Replaces the list; pass [] to remove them
});
```

`region` and `failoverRegions` can be updated independently, but `failoverRegions` must not include the configured `region`.

## Deleting a Sandbox

```typescript
// Permanently remove a sandbox and all its snapshots.
await sandbox.delete();
```

## Stopping a Sandbox

`stop()` is synchronous: it blocks until the VM is fully stopped and returns
the final session state, including the snapshot created during shutdown (when
`persistent: true`).

```typescript
const result = await sandbox.stop();
console.log(result.snapshot?.id);
console.log(result.activeCpuUsageMs);
console.log(result.networkTransfer); // { ingress, egress }
```

## Tags

Sandboxes support up to 5 key-value tags. Tags can be set at creation, updated
via `sandbox.update({ tags })`, and used as filters when listing.

```typescript
await Sandbox.create({ tags: { env: "staging", team: "infra" } });

const result = await Sandbox.list({ tags: { env: "staging" } });
```

## Listing Sandboxes, Sessions, and Snapshots

All list APIs use **cursor-based pagination** and return an async-iterable that
auto-paginates through every page. You can also iterate page-by-page or
collect all items at once.

### `Sandbox.list`

```typescript
const result = await Sandbox.list({
  namePrefix: "ci-", // Filter by name prefix
  tags: { env: "staging" }, // Filter by tags
  sortBy: "createdAt", // "createdAt" (default), "name", or "statusUpdatedAt"
  sortOrder: "desc", // "asc" or "desc" (default)
  limit: 50,
});

// Per-item async iteration (auto-paginates)
for await (const sandbox of result) {
  console.log(sandbox.name);
}

// Per-page iteration
for await (const page of result.pages()) {
  console.log(page.sandboxes.length);
}

// Collect everything
const all = await result.toArray();

// Or use the cursor directly
const next = result.pagination.next;
```

### `sandbox.listSessions` and `sandbox.listSnapshots`

```typescript
// List all VM sessions for this sandbox
const sessions = await sandbox.listSessions();
for await (const session of sessions) {
  console.log(session.sessionId, session.status);
}

// List snapshots belonging to this sandbox
const snapshots = await sandbox.listSnapshots();
for await (const snapshot of snapshots) {
  console.log(snapshot.snapshotId, snapshot.status);
}
```

### `Snapshot.list`

```typescript
const snapshots = await Snapshot.list({
  name: "my-dev-env", // Filter by sandbox name
  sortOrder: "desc",
  limit: 50,
});
for await (const snapshot of snapshots) {
  console.log(snapshot.snapshotId, snapshot.status);
}
```

## Sessions

A **Session** is a single running VM instance inside a sandbox. You typically
do not interact with sessions directly — the SDK creates and resumes them for
you — but you can inspect the current one.

```typescript
const session = sandbox.currentSession();
console.log(session.sessionId);
console.log(session.status); // "pending" | "running" | "stopping" | "stopped" | ...
```

## Snapshots

Snapshots save the entire sandbox filesystem to be reused later, for any
number of sandboxes.

Snapshots are stored in the sandbox's region; all regions where a snapshot is
available are listed in `snapshot.regions`. Creating a sandbox from a snapshot
in a region where the snapshot is not available fails with a
`snapshot_region_mismatch` error.

### Create a Snapshot

```typescript
const sandbox = await Sandbox.create();
await sandbox.runCommand("npm", ["install"]);

// Create snapshot (stops the sandbox)
const snapshot = await sandbox.snapshot({
  expiration: ms("14d"), // Default: 30 days, use 0 for no expiration
});
console.log("Snapshot ID:", snapshot.snapshotId);
```

### Default Snapshot Expiration and Retention

Configure default expiration and retention policy per sandbox:

```typescript
await Sandbox.create({
  name: "my-app",
  snapshotExpiration: ms("7d"), // Default TTL for any snapshot of this sandbox
  keepLastSnapshots: {
    count: 1, // Keep only the most recent snapshot (1-10)
    expiration: ms("30d"), // Override expiration for kept snapshots
    deleteEvicted: true, // Delete evicted snapshots immediately (default)
  },
});
```

`keepLastSnapshots: { count: 1 }` is the recommended setting when you only
care about the latest snapshot — it lets the SDK keep snapshot storage costs flat.

### List, Get, and Delete

```typescript
// List all snapshots in the project (auto-paginates)
const snapshots = await Snapshot.list();
for await (const snapshot of snapshots) {
  console.log(snapshot.snapshotId, snapshot.status);
}

// Get a specific snapshot
const snapshot = await Snapshot.get({ snapshotId: "snap_abc123" });

// Delete a snapshot
await snapshot.delete();
```

### Snapshot Tree

Snapshots form a tree: any sandbox created from another snapshot inherits a
parent → child relationship. Walk that tree to see ancestors or descendants of
a given snapshot.

```typescript
// Walk ancestors (default direction)
const ancestors = await Snapshot.tree({
  snapshotId: "snap_abc",
  sortOrder: "desc",
});
for await (const node of ancestors) {
  console.log(node.snapshotId, node.parentId);
}

// Walk descendants
const descendants = await Snapshot.tree({
  snapshotId: "snap_abc",
  sortOrder: "asc",
});
```

### Snapshot Rollback

Point an existing sandbox at a previous snapshot by updating
`currentSnapshotId`. New sessions will resume from that snapshot.

```typescript
await sandbox.update({ currentSnapshotId: "snap_previous" });
```

## Exposed Ports

```typescript
const sandbox = await Sandbox.create({ ports: [3000, 8000] });

// Get public URL for a port
const url = sandbox.domain(3000);
// Returns: https://subdomain.vercel.run
```

Replace the exposed port list at runtime with `sandbox.update({ ports })`. Any
currently exposed port not present in the new array is deregistered.

```typescript
await sandbox.update({ ports: [3000, 8443] });
```

## Timeout Management

```typescript
const sandbox = await Sandbox.create({
  timeout: ms("10m"), // Initial timeout, default of 5 minutes
});

// Extend timeout by 5 more minutes
await sandbox.extendTimeout(ms("5m"));
// New total: 15 minutes
```

## Authentication

### Vercel OIDC Token (Recommended)

```bash
# Pull development credentials
vercel link
vercel env pull
```

The SDK automatically uses `VERCEL_OIDC_TOKEN` from environment.

### Access Token (Alternative)

```typescript
const sandbox = await Sandbox.create({
  teamId: process.env.VERCEL_TEAM_ID!,
  projectId: process.env.VERCEL_PROJECT_ID!,
  token: process.env.VERCEL_TOKEN!,
  // ... other options
});
```

## Error Handling

```typescript
import { APIError, StreamError } from "@vercel/sandbox";

try {
  const sandbox = await Sandbox.create();
} catch (error) {
  if (error instanceof APIError) {
    console.error("API Error:", error.message, error.response.status);
  } else if (error instanceof StreamError) {
    console.error("Stream Error:", error.message);
  }
  throw error;
}
```

## Cancellation with AbortSignal

```typescript
const controller = new AbortController();

// Cancel after 30 seconds
setTimeout(() => controller.abort(), 30000);

const sandbox = await Sandbox.create({
  signal: controller.signal,
});

const result = await sandbox.runCommand({
  cmd: "npm",
  args: ["test"],
  signal: controller.signal,
});
```

## Limitations

| Limitation      | Details                                                                         |
| --------------- | ------------------------------------------------------------------------------- |
| Max vCPUs       | 4 vCPUs on Hobby, 8 vCPUs on Pro, 32 vCPUs on Enterprise (2048 MB RAM per vCPU) |
| Max ports       | 15 exposed ports                                                                |
| Max tags        | 5 key-value tags per sandbox                                                    |
| Max timeout     | 24 hours (Pro/Enterprise), 45 minutes (Hobby)                                   |
| Default timeout | 5 minutes                                                                       |
| Base system     | Ubuntu 26.04                                                                    |
| User context    | `ubuntu` user                                                                   |
| Writable path   | `/vercel/sandbox`                                                               |
| Regions         | One primary region per sandbox, plus optional failover regions. Snapshots restore only in regions where they are available. See the Vercel docs for the region list. |

## System Packages

The default image includes Node.js 24, Bun, Python 3.14, pnpm, uv, Git, GitHub
CLI, coding agents, and common development and debugging utilities.

Install additional packages with sudo:

```typescript
await sandbox.runCommand({
  cmd: "apt-get",
  args: ["update"],
  sudo: true,
});
await sandbox.runCommand({
  cmd: "apt-get",
  args: ["install", "-y", "package-name"],
  sudo: true,
});
```

This is fine for one-offs. For reproducible dependencies or a different base
environment, use a [custom image](#from-a-custom-image-vcr) instead.

## CLI Quick Reference

```bash
# Install CLI
pnpm i -g sandbox

# Login / Logout
sandbox login
sandbox logout

# Create and connect
sandbox create --connect
sandbox create --name my-app
sandbox create --image my-repo:v1            # Boot from a VCR image
sandbox create --non-persistent              # Disable filesystem persistence
sandbox create --snapshot-expiration 7d      # Default snapshot TTL
sandbox create --keep-last-snapshots 1       # Retention policy
sandbox create --tag env=staging             # Repeatable
sandbox create --region <region>             # Defaults to iad1; see the Vercel docs for available regions
sandbox create --failover-regions <region>,<region>  # Comma-separated
sandbox create --failover-regions none               # No failover, overrides the project default

# Fork an existing sandbox (inherits config, incl. env; --env replaces it)
sandbox fork <source>
sandbox fork <source> --name my-fork --vcpus 4 --env FOO=1
sandbox fork <source> --region <region>      # Override the region copied from the source

# List sandboxes (paginated, filterable)
sandbox ls
sandbox ls --name-prefix ci- --sort-by name
sandbox ls --tag env=staging --limit 100 --cursor <token>

# Run a command in a new sandbox (create + exec in one step)
sandbox run -- node -e "console.log('hello')"
sandbox run --name my-app -- npm test        # Resumes existing sandbox if present
sandbox run --stop -- npm build              # Stop the session when the command exits
sandbox run --rm -- npm build                # DELETES the sandbox after running

# Execute command in an existing sandbox
sandbox exec <name> -- npm install
sandbox exec <name> --stop -- npm build

# Start an interactive shell
sandbox connect <name>

# Copy files
sandbox cp local-file.txt <name>:/vercel/sandbox/

# Stop sandbox (synchronous; reports snapshot + usage)
sandbox stop <name>

# Permanently delete sandbox and all its snapshots
sandbox remove <name>

# Sessions
sandbox sessions list <name>

# Snapshots
sandbox snapshot <name>
sandbox snapshots list --name <name>
sandbox snapshots get <snapshot-id>
sandbox snapshots remove <snapshot-id>
sandbox snapshots tree <name>                # Walk the tree from the sandbox's current snapshot
sandbox snapshots tree <name> --cursor <snapshot-id> --sort-order asc

# Config (view + update any sandbox parameter)
sandbox config list <name>
sandbox config vcpus <name> <count>
sandbox config timeout <name> <duration>
sandbox config persistent <name> <true|false>
sandbox config region <name> <region>
sandbox config failover-regions <name> <region,...|none>
sandbox config snapshot-expiration <name> <duration|none>
sandbox config keep-last-snapshots <name> <count>
sandbox config keep-last-snapshots-for <name> <duration|none>
sandbox config delete-evicted-snapshots <name> <true|false>
sandbox config current-snapshot <name> <snapshot-id>
sandbox config network-policy <name> --network-policy deny-all
sandbox config tags <name> --tag env=prod
```

## Common Patterns

### Dev Server Pattern (Persistent)

```typescript
const sandbox = await Sandbox.getOrCreate({
  name: "my-dev-env",
  source: { type: "git", url: "https://github.com/org/repo.git" },
  ports: [3000],
  timeout: ms("30m"),
  onCreate: async (sbx) => {
    await sbx.runCommand({ cmd: "npm", args: ["install"], cwd: "repo" });
  },
  onResume: async (sbx) => {
    await sbx.runCommand({
      cmd: "npm",
      args: ["run", "dev"],
      cwd: "repo",
      detached: true,
    });
  },
});

console.log("App running at:", sandbox.domain(3000));
```

### Build and Test Pattern (Ephemeral)

```typescript
const repoUrl = "https://github.com/org/repo.git";
const repoDir = "repo";

await using sandbox = await Sandbox.create({
  source: { type: "git", url: repoUrl },
  persistent: false, // Skip snapshotting on shutdown
  snapshotExpiration: ms("1d"), // Short TTL for any incidental snapshot
});

const install = await sandbox.runCommand({
  cmd: "npm",
  args: ["ci"],
  cwd: repoDir,
});
if (install.exitCode !== 0) throw new Error("Install failed");

const build = await sandbox.runCommand({
  cmd: "npm",
  args: ["run", "build"],
  cwd: repoDir,
});
if (build.exitCode !== 0) throw new Error("Build failed");

const test = await sandbox.runCommand({
  cmd: "npm",
  args: ["test"],
  cwd: repoDir,
});
process.exit(test.exitCode);
```

### Base Sandbox + Forks Pattern

Maintain a single "base" sandbox with dependencies installed, and spawn fresh
children from it with `Sandbox.fork`. Each fork inherits the base's config
and is seeded from its current snapshot — no need to store snapshot IDs in
your code. New base snapshots are picked up automatically on the next fork.

```typescript
// Once: bootstrap the base sandbox
await Sandbox.getOrCreate({
  name: "my-base",
  keepLastSnapshots: { count: 5 }, // Keep storage flat
  onCreate: async (sbx) => {
    await sbx.runCommand("npm", ["install", "-g", "typescript", "tsx"]);
  },
});

// On every run: fork the base sandbox
async function runFromBase(code: string) {
  await using sandbox = await Sandbox.fork({
    sourceSandbox: "my-base",
    persistent: false,
  });
  await sandbox.writeFiles([
    { path: "/vercel/sandbox/index.ts", content: Buffer.from(code) },
  ]);
  return sandbox.runCommand("tsx", ["index.ts"]);
}
```

### Long-Lived Workspace Pattern

```typescript
// Idempotent: first call creates, subsequent calls resume
const sandbox = await Sandbox.getOrCreate({
  name: `workspace-${userId}`,
  keepLastSnapshots: { count: 1, expiration: ms("5d") },
  onCreate: async (sbx) => {
    await sbx.runCommand("git", ["clone", repoUrl, "."]);
    await sbx.runCommand("npm", ["install"]);
  },
});

// Use the sandbox — auto-resumes if it was stopped
await sandbox.runCommand("git", ["pull"]);
```