fabro/docs/integrations/daytona.mdx

---
title: "Daytona"
description: "Run Arc workflows in sandboxed Daytona cloud environments"
---

[Daytona](https://daytona.io) provides cloud-hosted sandbox VMs for Arc workflows. Each run gets an ephemeral, isolated environment with its own filesystem, network, and compute resources — keeping your host machine clean and giving agents a reproducible workspace.

## What the Daytona integration enables

| Feature | How it's used |
|---|---|
| **Sandboxed execution** | Agent tool calls (shell commands, file edits, grep, glob) run inside a cloud VM instead of on the host |
| **Snapshots** | Pre-built environment images so each run starts with dependencies already installed |
| **SSH access** | Connect to a running sandbox for live debugging |
| **Network controls** | Restrict agent egress with block-all or CIDR-based allow lists |

## Prerequisites

- A `DAYTONA_API_KEY` environment variable (get one from [app.daytona.io](https://app.daytona.io))
- A [GitHub App](/integrations/github) configured via the web UI (required for private repository cloning and checkpoint pushing)

## Configuration

Set the sandbox provider in your run config TOML or via CLI flag:

```bash
arc run start workflow.dot --sandbox daytona
```

```toml title="run.toml"
[sandbox]
provider = "daytona"
```

A full configuration example with all Daytona-specific options:

```toml title="run.toml"
[sandbox]
provider = "daytona"
preserve = false

[sandbox.daytona]
auto_stop_interval = 60

[sandbox.daytona.labels]
project = "arc"
env = "staging"
team = "platform"

[sandbox.daytona.snapshot]
name = "rust-dev"
cpu = 4
memory = 8
disk = 20
dockerfile = "FROM rust:1.85-slim-bookworm\nRUN apt-get update && apt-get install -y git ripgrep"
```

See [Server Configuration](/administration/server-configuration) for the full reference on all sandbox fields and server defaults.

### Network access control

Control outbound network access with the `network` field. Three modes are available:

```toml title="run.toml"
# Full access (default)
[sandbox.daytona]
network = "allow_all"

# Block all egress
[sandbox.daytona]
network = "block"

# CIDR-based allow list
[sandbox.daytona]
network = { allow_list = ["208.80.154.232/32", "10.0.0.0/8"] }
```

Use `"block"` or a CIDR allow list when running untrusted or generated code to prevent agents from making arbitrary network requests.

## Snapshots

Snapshots let you pre-build an environment image so each run starts with dependencies already installed rather than installing them in setup commands every time.

```toml title="run.toml"
[sandbox.daytona.snapshot]
name = "my-snapshot"
cpu = 4
memory = 8
disk = 20
dockerfile = "FROM node:20-slim\nRUN apt-get update && apt-get install -y git"
```

When a run starts with a snapshot configured, Arc looks up the snapshot by name. If it doesn't exist and a `dockerfile` is provided, Arc creates it automatically and polls until it reaches `Active` state (up to 10 minutes). If the snapshot already exists, it's reused immediately.

<Note>
If the snapshot doesn't exist and no `dockerfile` is provided, the run fails immediately. Without a snapshot, sandboxes are created from the default `ubuntu:22.04` image.
</Note>

## Private repositories

Arc automatically clones the current repository into the sandbox at `/home/daytona/workspace`. Public repositories work without extra configuration. Private repositories require a [GitHub App](/integrations/github) — Arc uses short-lived Installation Access Tokens scoped to the specific repository.

If the clone fails without a GitHub App configured, Arc suggests running the setup flow:

```
Git clone failed: ... If this is a private repository,
configure a GitHub App with `arc setup` and install it
for your organization.
```

## SSH access

Connect to a running Daytona sandbox via SSH for live debugging:

```bash
arc run start workflow.dot --sandbox daytona --ssh
```

This creates temporary SSH credentials (valid for 60 minutes) and prints the connection command:

```
SSH access ready: ssh daytona@arc-20260307-143022-a3f2.ssh.daytona.io
```

<Note>
SSH credentials cannot be refreshed during a run. To keep the sandbox alive after the run completes, combine `--ssh` with `--preserve-sandbox`.
</Note>

## Sandbox lifecycle

Each sandbox gets a unique timestamped name (e.g. `arc-20260307-143022-a3f2`) and is created as ephemeral. By default, sandboxes are destroyed when the run finishes.

### Preservation

To keep a sandbox alive for debugging:

```bash
arc run start workflow.dot --sandbox daytona --preserve-sandbox
```

Or in the run config:

```toml title="run.toml"
[sandbox]
provider = "daytona"
preserve = true
```

When preserved, Arc prints the sandbox name so you can find it in the [Daytona dashboard](https://app.daytona.io/dashboard/sandboxes).

### Auto-stop

The `auto_stop_interval` setting tells Daytona to stop the sandbox after a period of inactivity, saving costs for preserved or long-running sandboxes:

```toml title="run.toml"
[sandbox.daytona]
auto_stop_interval = 30
```

## Server defaults

When running via `arc serve`, the server config at `~/.arc/server.toml` can set default Daytona settings for all runs. Run config TOML values override server defaults. Labels are **merged** — run config labels win on key collisions. The `network` setting uses simple override (run config replaces the server default entirely).

See [Server Configuration](/administration/server-configuration) for details.

## Troubleshooting

### "Failed to create Daytona sandbox"

The `DAYTONA_API_KEY` environment variable is missing or invalid. Verify it's set in your `.env` file and check that it's a valid key from [app.daytona.io](https://app.daytona.io).

### "Snapshot does not exist and no dockerfile provided"

The run config references a snapshot name that doesn't exist on Daytona, and no `dockerfile` is provided to create it. Either create the snapshot manually in the Daytona dashboard or add a `dockerfile` field to `[sandbox.daytona.snapshot]`.

### "Timed out waiting for snapshot to become active"

Snapshot creation took longer than 10 minutes. This can happen with large Dockerfiles. Check the snapshot status in the Daytona dashboard — it may still be building. Subsequent runs will reuse the snapshot once it's active.

### Git clone fails for private repositories

See [Private repositories](#private-repositories) above. You need a GitHub App configured and installed on the repository's organization or account.

### Stall watchdog kills the run

Long-running commands in Daytona sandboxes may trigger the 1800-second stall watchdog if they don't produce events. For workflows with long-running operations, increase the `stall_timeout` in the workflow graph:

```dot
digraph Example {
    graph [stall_timeout="1200"]
}
```