fabro/docs/public/execution/environments.mdx

---
title: "Environments"
description: "Reusable named execution environments for workflow runs"
---

Fabro separates **environments** from **sandboxes**:

- An **environment** is reusable desired configuration: provider, image, resources, network, lifecycle, labels, and environment variables.
- A **sandbox** is the concrete runtime instance Fabro creates for a run from the selected environment.

<Warning>
Older pre-v1.0 config files that still use `[run.sandbox]` are temporarily auto-migrated when Fabro loads them from disk. Fabro writes a sibling `*.legacy-sandbox-migration.bak` file, rewrites the config to `[run.environment]` plus `[environments.default]`, and then continues startup.

This compatibility rewrite only handles direct field mappings. Unsupported legacy fields fail with a migration message that lists the keys to edit manually. The rewrite path will be removed before v1.0.
</Warning>

Runs select environments by slug:

```toml title="workflow.toml"
[run.environment]
id = "fabro-dev"
```

Environment catalogs can live in `settings.toml`, `.fabro/project.toml`, or `workflow.toml`, and merge through the normal settings precedence. The built-in default is `default`, a Docker environment using `buildpack-deps:noble`.

## Defining environments

```toml title="workflow.toml"
[run.environment]
id = "fabro-dev"

[environments.fabro-dev]
provider = "daytona" # local | docker | daytona

[environments.fabro-dev.image]
dockerfile = { path = "Dockerfile" }

[environments.fabro-dev.resources]
cpu = 8
memory = "16GB"
disk = "20GB"

[environments.fabro-dev.network]
mode = "cidr_allow_list"       # allow_all | block | cidr_allow_list
allow = ["10.0.0.0/8"]

[environments.fabro-dev.lifecycle]
preserve = false
stop_on_terminal = true
auto_stop = "30m"

[environments.fabro-dev.labels]
repo = "fabro-sh/fabro"

[environments.fabro-dev.env]
NODE_ENV = "development"
```

Run-level overrides are sparse and apply only to the selected environment:

```toml title="workflow.toml"
[run.environment]
id = "fabro-dev"

[run.environment.resources]
memory = "32GB"

[run.environment.lifecycle]
preserve = true
```

`env` and `labels` merge by key.

## Selecting an environment from the CLI

Use `--environment` with an environment slug:

```bash
fabro run workflow.fabro --environment fabro-dev
fabro preflight workflow.fabro --environment ci
fabro server start --environment default
```

`--preserve-sandbox` still controls the concrete runtime instance lifecycle for a run. Runtime commands such as `fabro sandbox ssh` keep the word "sandbox" because they operate on an already-created runtime instance.

## Built-in default

```toml
[run.environment]
id = "default"

[environments.default]
provider = "docker"

[environments.default.image]
docker = "buildpack-deps:noble"

[environments.default.resources]
cpu = 2
memory = "4GB"

[environments.default.lifecycle]
preserve = false
stop_on_terminal = true
```

## Provider mappings

| Environment field | Local | Docker | Daytona |
|---|---|---|---|
| `image.docker` | Ignored | Docker image | Error |
| `image.dockerfile` | Ignored | Warning; ignored | Snapshot Dockerfile; Fabro computes the snapshot name |
| `resources.cpu` | Warning; ignored | `cpu_quota = cpu * 100000` | Snapshot CPU |
| `resources.memory` | Warning; ignored | Container memory limit | Snapshot memory |
| `resources.disk` | Warning; ignored | Warning; ignored | Snapshot disk |
| `network.mode = "allow_all"` | Host network | Docker default bridge | Daytona allow-all |
| `network.mode = "block"` | Error | Docker `none` network | Daytona block |
| `network.mode = "cidr_allow_list"` | Error | Error | Daytona CIDR allow-list |
| `labels` | Warning; ignored | Warning; ignored | Daytona labels |
| `lifecycle.auto_stop` | Warning; ignored | Warning; ignored | Daytona auto-stop |
| `env` | Process environment overlay | Container environment | Sandbox environment |

## Local

`local` runs tools directly in the resolved working directory. It offers no filesystem or network isolation, so use it only for trusted workflows.

```toml
[run.environment]
id = "host"

[environments.host]
provider = "local"
```

Fabro hard-errors if a local environment asks for blocked or CIDR-restricted networking because the provider cannot enforce it.

## Docker

Docker runs tools inside a container created from `image.docker`. Docker is the built-in default provider.

```toml
[run.environment]
id = "ci"

[environments.ci]
provider = "docker"

[environments.ci.image]
docker = "buildpack-deps:noble"

[environments.ci.resources]
cpu = 2
memory = "4GB"

[environments.ci.network]
mode = "block"
```

Docker and Daytona are clone-based providers. When a run has a GitHub origin, Fabro clones it into the provider workspace. Set `[run.clone] enabled = false` to start with an empty workspace.

## Daytona

Daytona runs tools in a cloud sandbox. Without `image.dockerfile`, Fabro uses Daytona's built-in `daytona-medium` snapshot. With `image.dockerfile`, Fabro computes a deterministic internal snapshot name from the Dockerfile, resource hints, a single-tenant scope, and the Daytona API key.

```toml
[run.environment]
id = "cloud"

[environments.cloud]
provider = "daytona"

[environments.cloud.image]
dockerfile = { path = "Dockerfile" }

[environments.cloud.resources]
cpu = 4
memory = "8GB"
disk = "20GB"

[environments.cloud.lifecycle]
auto_stop = "30m"

[environments.cloud.network]
mode = "cidr_allow_list"
allow = ["208.80.154.232/32", "10.0.0.0/8"]
```