Sandboxes

How Lightdash runs LLM-generated code safely in isolated sandboxes, and how to configure the sandbox provider on a self-hosted instance.

🛠 This page is for engineering teams self-hosting their own Lightdash instance. On Lightdash Cloud, sandboxes are fully managed for you — there’s nothing to configure.

What sandboxes are for

Some Lightdash features use an AI agent (Claude Code) that writes and runs code on your behalf. Today that’s:

• AI writeback — the agent edits your dbt project (e.g. adds a metric or dimension), runs lightdash compile to validate it, and opens a pull request.
• Data app generation — the agent generates and builds a small web app from a prompt.

Running model-generated code directly on the Lightdash server would be unsafe: the code is untrusted, can run arbitrary commands, and needs its own toolchain (git, dbt, the Lightdash CLI, Node). Lightdash instead runs each agent inside a sandbox — an isolated, disposable environment with a constrained network. The agent does its work there, Lightdash collects the result (a PR, a built app), and the sandbox is torn down.

Sandboxes are also what make these features fast and multi-turn: a sandbox can be suspended between turns and resumed later, so a conversation with the agent keeps its state without holding a container open the whole time.

Sandbox providers

The sandbox backend is pluggable. Lightdash talks to a provider-neutral interface, so the same feature code runs on whichever backend your deployment is configured for. You select the provider with the SANDBOX_PROVIDER environment variable.

Provider	SANDBOX_PROVIDER	Use for	Isolation
E2B (default)	e2b	Production / managed	microVM
AWS Lambda MicroVMs	lambda-microvm	Production on AWS (self-hosted)	microVM
Local Docker	docker	Local development only	container

Both E2B and AWS Lambda MicroVMs are supported production backends. E2B is the managed default; Lambda MicroVMs is for teams who want sandboxes to run inside their own AWS account. More providers (Kubernetes, ECS) are planned.

The local Docker provider is for development only. It launches plain Docker containers via the Docker socket, which is root-equivalent on the host and provides no real isolation between the sandbox and your machine. It refuses to start when NODE_ENV=production. Do not use it for a production deployment.

E2B (production default)

E2B runs each sandbox as a Firecracker microVM in E2B’s cloud. It’s the default — if you don’t set SANDBOX_PROVIDER, Lightdash uses E2B.

To use it you need an E2B account and API key, and the agent needs an Anthropic API key:

SANDBOX_PROVIDER=e2b            # default, can be omitted
E2B_API_KEY=e2b_...            # from your E2B dashboard
ANTHROPIC_API_KEY=sk-ant-...   # the agent (Claude Code) runs inside the sandbox

The sandbox images are E2B templates. Lightdash uses separate templates for data apps and for AI writeback so they can be pinned or rolled back independently. These default to the published Lightdash templates and rarely need to be set:

E2B_TEMPLATE_NAME=lightdash/lightdash-data-app
E2B_TEMPLATE_TAG=<lightdash-version>             # defaults to your Lightdash version
E2B_AI_WRITEBACK_TEMPLATE_NAME=lightdash/lightdash-ai-writeback
E2B_AI_WRITEBACK_TEMPLATE_TAG=<lightdash-version>

AWS Lambda MicroVMs (self-hosted production)

AWS Lambda MicroVMs run each sandbox as a Firecracker microVM inside your own AWS account, so untrusted agent code and your repository contents never leave your infrastructure. The microVMs have no public IP — your backend reaches each one through an AWS-managed endpoint that requires a short-lived per-microVM token — and you control their outbound network access (see Networking and IAM).

This is the recommended sandbox provider for customers deploying Lightdash on AWS — it keeps the sandbox boundary inside your existing AWS account and avoids sending agent workloads or repository contents to a third-party service.

Prerequisites

Provision these with your own IaC, in the same AWS account and region your Lightdash backend already runs in:

• Two MicroVM images — one for data app generation and one for AI writeback (they bundle different toolchains). Build them from the Dockerfiles in the Lightdash repo (sandboxes/data-apps/, sandboxes/ai-writeback/, and the exec agent in sandboxes/microvm-agent/), push them to ECR, and register each as a Lambda MicroVM image on the AWS-managed al2023 base — ARM_64, 4 GB memory, with the agent’s /ready hook on port 8080. Each registration returns an image ARN for the config below.
• Control-plane permissions on your backend’s existing IAM role — add RunMicrovm, GetMicrovm, SuspendMicrovm, ResumeMicrovm, TerminateMicrovm, and CreateMicrovmAuthToken.

Registering an image uses AWS’s create-microvm-image, which needs a build role (trusting lambda.amazonaws.com) and an S3 location to stage the build context. These are build-time only — not the S3 bucket Lightdash already uses for results and snapshots, and the backend never touches them at runtime.

Configure the provider

SANDBOX_PROVIDER=lambda-microvm
ANTHROPIC_API_KEY=sk-ant-...   # the agent (Claude Code) runs inside the microVM

# Region the microVMs run in (defaults to eu-west-1, the EU launch region)
LAMBDA_MICROVM_REGION=eu-west-1

# The image ARNs from registering the two MicroVM images above. Required.
LAMBDA_MICROVM_DATA_APP_IMAGE_ARN=arn:aws:lambda:<region>:<account>:microvm-image/...
LAMBDA_MICROVM_AI_WRITEBACK_IMAGE_ARN=arn:aws:lambda:<region>:<account>:microvm-image/...

The backend uses its ambient AWS credentials (instance role / IRSA / standard SDK credential chain) to call the Lambda MicroVMs control plane, so no access keys are configured here.

Networking and IAM

Configure the network connectors before going to production. The AWS-managed defaults give the microVM open inbound and outbound access, which means untrusted agent code can reach the public internet from inside your AWS account. We currently recommend pointing the egress connector at a VPC connector that has no outbound access by default, and only opening up the destinations the agent actually needs (your dbt repository host, the Anthropic / Bedrock API, your ECR registry).

Override these to tighten the network boundary or to give the microVM an IAM role:

# IAM role the microVM assumes (e.g. to pull from a private ECR or reach AWS APIs)
LAMBDA_MICROVM_EXECUTION_ROLE_ARN=arn:aws:iam::...:role/lightdash-sandbox

# Network connectors. Default to AWS-managed open ingress/egress; point these at
# your own VPC connectors to constrain traffic. We strongly recommend an egress
# connector that denies outbound traffic by default.
LAMBDA_MICROVM_INGRESS_CONNECTOR_ARN=arn:aws:lambda:<region>:aws:network-connector:aws-network-connector:ALL_INGRESS
LAMBDA_MICROVM_EGRESS_CONNECTOR_ARN=arn:aws:lambda:<region>:aws:network-connector:aws-network-connector:INTERNET_EGRESS

Local Docker provider (development)

For local development you can run sandboxes as plain Docker containers on your own machine — no E2B account required. This is the recommended way to work on or try the AI features locally.

It uses the same images E2B builds, but as plain local Docker images. Two separate images are used (different toolchains), mirroring the two E2B templates:

Image (default tag)	Built from	Used by
lightdash-sandbox:local	sandboxes/data-apps/	Data app generation
lightdash-ai-writeback:local	sandboxes/ai-writeback/	AI writeback

Prerequisites

• Docker running locally, with the daemon reachable from the Lightdash backend.
• S3-compatible object storage configured (locally this is MinIO). Suspended-sandbox snapshots are tarred to object storage so a conversation survives the container being destroyed — see external object storage.
• An Anthropic API key (ANTHROPIC_API_KEY) for the agent.

Setup

1. Build the local sandbox images (each builds from sandboxes/<feature>/):

   ./sandboxes/data-apps/build-local-image.sh        # -> lightdash-sandbox:local
   ./sandboxes/ai-writeback/build-local-image.sh     # -> lightdash-ai-writeback:local
   

   These are large (the writeback image bundles dbt, the Lightdash CLI and Claude Code) and only need rebuilding when the sandbox toolchain changes.

2. Point Lightdash at the Docker provider:

   SANDBOX_PROVIDER=docker
   # optional — these are the defaults:
   SANDBOX_DOCKER_IMAGE=lightdash-sandbox:local
   SANDBOX_AI_WRITEBACK_DOCKER_IMAGE=lightdash-ai-writeback:local
   

3. Restart the backend and the scheduler so both pick up the new environment. Data app generation runs in the scheduler worker, so a stale SANDBOX_PROVIDER there will keep it on E2B. (With PM2, a plain restart reuses the cached env — delete and re-start the processes, or restart with --update-env, to actually reload the env file.)

Snapshot lifecycle

Every turn suspends its own sandbox, so in steady state nothing sits idle. For the Lambda MicroVMs provider, two timers configure the AWS-side idle policy as a backstop — when to auto-suspend a sandbox left running and when to auto-terminate a suspended one:

SANDBOX_IDLE_TIMEOUT_MS=1800000        # auto-suspend a running-but-idle microVM (default 30 min)
SANDBOX_SNAPSHOT_RETENTION_MS=604800000 # auto-terminate a suspended microVM (default 7 days); also how long a thread stays resumable

These are read only by the Lambda MicroVMs provider. E2B manages idle sandboxes itself, and the Docker dev provider has no idle handling.

Environment variable reference

Variable	Default	Description
SANDBOX_PROVIDER	e2b	Sandbox backend: e2b, lambda-microvm, or docker.
ANTHROPIC_API_KEY	—	API key for the Claude Code agent running inside the sandbox.
E2B_API_KEY	—	E2B API key (required when SANDBOX_PROVIDER=e2b).
E2B_TEMPLATE_NAME	lightdash/lightdash-data-app	E2B template for data app sandboxes.
E2B_TEMPLATE_TAG	Lightdash version	Tag of the data app template to launch.
E2B_AI_WRITEBACK_TEMPLATE_NAME	lightdash/lightdash-ai-writeback	E2B template for writeback sandboxes.
E2B_AI_WRITEBACK_TEMPLATE_TAG	Lightdash version	Tag of the writeback template to launch.
LAMBDA_MICROVM_REGION	eu-west-1	AWS region the microVMs run in (lambda-microvm).
LAMBDA_MICROVM_DATA_APP_IMAGE_ARN	—	Image ARN for data app microVMs (required when SANDBOX_PROVIDER=lambda-microvm).
LAMBDA_MICROVM_AI_WRITEBACK_IMAGE_ARN	—	Image ARN for writeback microVMs (required when SANDBOX_PROVIDER=lambda-microvm).
LAMBDA_MICROVM_EXECUTION_ROLE_ARN	—	Optional IAM role the microVM assumes.
LAMBDA_MICROVM_INGRESS_CONNECTOR_ARN	AWS-managed ALL_INGRESS	Optional ingress network connector.
LAMBDA_MICROVM_EGRESS_CONNECTOR_ARN	AWS-managed INTERNET_EGRESS	Optional egress network connector.
SANDBOX_DOCKER_IMAGE	lightdash-sandbox:local	Local image for data app sandboxes (docker provider).
SANDBOX_AI_WRITEBACK_DOCKER_IMAGE	lightdash-ai-writeback:local	Local image for writeback sandboxes (docker provider).
SANDBOX_IDLE_TIMEOUT_MS	1800000 (30 min)	Lambda MicroVMs idle policy: auto-suspend a running-but-idle microVM. Ignored by e2b/docker.
SANDBOX_SNAPSHOT_RETENTION_MS	604800000 (7 days)	Lambda MicroVMs idle policy: auto-terminate a suspended microVM (also how long a thread stays resumable). Ignored by e2b/docker.