Base image

Creating template

When creating a template, you can specify options:

const template = Template({
  fileContextPath: ".", // Custom file context path
  fileIgnorePatterns: [".git", "node_modules"], // File patterns to ignore
});

File ignoring: The SDK automatically reads .dockerignore files and combines them with your fileIgnorePatterns (TypeScript) or file_ignore_patterns (Python). Files matching these patterns are excluded from uploads and hash calculations.

Defining base image

Every template starts with a base image that provides the foundation for your sandbox environment.

Predefined base images

Use convenience methods for common base images with Ubuntu, Debian, Python, Node.js, or Bun:

template.fromUbuntuImage("22.04"); // ubuntu:22.04
template.fromDebianImage("stable-slim"); // debian:stable-slim
template.fromPythonImage("3.13"); // python:3.13
template.fromNodeImage("lts"); // node:lts
template.fromBunImage("1.3"); // oven/bun:1.3

Custom base image

Use any Docker image from Docker Hub or other registries:

template.fromImage("custom-image:latest");

Default E2B base image

Use the default E2B base image, which comes pre-configured for sandbox environments:

template.fromBaseImage(); // e2bdev/base

base is also the template used when you call Sandbox.create() without specifying one. It is Debian-based and comes with common tooling pre-installed: Python 3, Node.js, Yarn, git, curl, build-essential, and the GitHub CLI (gh). For the exact contents, see the public Dockerfile: templates/base/e2b.Dockerfile.

Default resources

A sandbox gets its CPU and memory from the template it’s built on. A sandbox built from base starts with 2 vCPU and 512 MiB of RAM.

You can override CPU and memory when you build a template (cpuCount/cpu_count, memoryMB/memory_mb). Disk size is not a default you set per sandbox; it’s determined by your project’s tier limit and applied at build time (see Build limits).

Build from existing template

Extend an existing template from your project or organization:

template.fromTemplate("my-template"); // Your project's template
template.fromTemplate("acme/other-template"); // Full namespaced reference

Parsing existing Dockerfiles

Convert existing Dockerfiles to template format using fromDockerfile():

const dockerfileContent = `
FROM ubuntu:22.04
RUN apt-get update && apt-get install -y curl
WORKDIR /app
COPY . .
ENV NODE_ENV=production
ENV PORT=3000
USER appuser`;

const template = Template()
  .fromDockerfile(dockerfileContent)
  .setStartCmd("npm start", waitForTimeout(5_000));

Dockerfile instructions support