---
layout: docs
page_title: Raw Fork/Exec task driver
description: Nomad's Raw Exec task driver lets you execute commands with no resource isolation. Review the Isolated Fork/Exec task driver capabilities, plugin options, client requirements, and client attributes.
---

# Configure the Raw Fork/Exec task driver

Name: `raw_exec`

The `raw_exec` driver is used to execute a command for a task without any
isolation. Further, the task is started as the same user as the Nomad process.
As such, it should be used with extreme care and is disabled by default.

## Capabilities

The `raw_exec` driver implements the following [capabilities](/nomad/plugins/author/task-driver#capabilities-capabilities-error).

| Feature              | Implementation |
| -------------------- | -------------- |
| `nomad alloc signal` | true           |
| `nomad alloc exec`   | true           |
| filesystem isolation | none           |
| network isolation    | host, group    |
| volume mounting      | none           |

## Client Requirements

The `raw_exec` driver can run on all supported operating systems. For security
reasons, it is disabled by default. To enable raw exec, the Nomad client
configuration must explicitly enable the `raw_exec` driver in the plugin's options:

```
plugin "raw_exec" {
  config {
    enabled = true
  }
}
```

Nomad versions before v0.9 use the following client configuration. This configuration is
also supported in Nomad v0.9.0, but is deprecated in favor of the plugin block:

```
client {
  options = {
    "driver.raw_exec.enable" = "1"
  }
}
```

## Plugin Options

- `enabled` - Specifies whether the driver should be enabled or disabled.
  Defaults to `false`.

- `denied_host_uids` - (Optional) Specifies a comma-separated list of host uids to
  deny. Ranges can be specified by using a hyphen separating the two inclusive ends.
  If a "user" value is specified in task configuration and that user has a user id in
  the given ranges, the task will error before starting. This will not be checked on Windows
  clients.

```hcl
config {
  denied_host_uids = "0,10-15,22"
}
```

- `denied_host_gids` - (Optional) Specifies a comma-separated list of host gids to
  deny. Ranges can be specified by using a hyphen separating the two inclusive ends.
  If a "user" value is specified in task configuration and that user is part of
  any groups with gid's in the specified ranges, the task will error before
  starting. This will not be checked on Windows clients.

```hcl
config {
  denied_host_gids = "2,4-8"
}
```

- `denied_envvars` - (Optional) Passes a list of environment variables that
  the driver should scrub from all task environments. Supports globbing with "*"
  wildcard accepted as prefix and/or suffix.

```hcl
config {
  denied_envvars = ["AWS_SECRET_KEY", "*_TOKEN"]
}
```
## Client Options

~> Note: client configuration options will soon be deprecated. Please use
[plugin options][plugin-options] instead. See the [plugin block][plugin-block] documentation for more information.

- `driver.raw_exec.enable` - Specifies whether the driver should be enabled or
  disabled. Defaults to `false`.

## Client Attributes

The `raw_exec` driver will set the following client attributes:

- `driver.raw_exec` - This will be set to "1", indicating the driver is available.

## Resource Isolation

The `raw_exec` driver provides no filesystem isolation.

If the launched process creates a new process group, it is possible that
Nomad will leak processes on shutdown unless the application forwards signals
properly. Nomad will not leak any processes if cgroups are being used to
manage the process tree. Cgroups are used on Linux when Nomad is being run with
appropriate privileges, and the cgroup system is mounted.

If the cluster is configured with memory oversubscription enabled, a task using
the `raw_exec` driver can be configured to have no maximum memory limit by
setting `memory_max = -1`.

```hcl
resources {
  cpu        = 500
  memory     = 128
  memory_max = -1 # no limit
}
```

## Next steps

[Use the `raw_exec` driver in a job](/nomad/docs/job-declare/task-driver/raw_exec).

[hardening]: /nomad/docs/deploy/production/requirements#user-permissions
[service]: /nomad/docs/deploy/production/windows-service
[plugin-options]: #plugin-options
[plugin-block]: /nomad/docs/configuration/plugin
