Exec

Overview

The Exec resource lets you execute scripts and commands either locally on the host machine or remotely inside containers. It provides a flexible way to automate environment setup, system configuration, and custom workflows as part of your lab sandbox — without needing to write configuration files.

Through the UI, you can define exec settings such as the script content, execution mode (local or remote), timeout, environment variables, and output handling. For remote execution, you can either create a new container or target an existing one, with support for network attachments, volume mounts, and user configuration.

Exec resources are ideal for tasks like installing dependencies, configuring services, running build scripts, and initializing databases during lab setup.

For more information on the exec sandbox resource, please refer to the Exec Reference documentation.

Execution modes

The exec resource supports three distinct execution modes:

• Local execution — Runs the script directly on the host machine. Supports working directory configuration and daemon mode for background processes.
• Remote execution (new container) — Creates a new container from a specified image and runs the script inside it. Supports network attachments, volume mounts, and user configuration.
• Remote execution (existing container) — Runs the script inside an already running container by selecting it from a list of existing ones. Useful for operations that need to interact with container-specific state.

Creating an Exec resource

Exec resources can be created in the Sandbox tab. To create a new Exec resource, navigate to the Sandbox tab and click the + button. Select Exec from the dropdown menu.

Start by naming the exec resource. Note that this is an internal name. You must provide a script to execute, and optionally configure the execution mode, timeout, environment variables, and other settings.

Setting the script

The Script field is the core of the exec resource, where you write your script directly in the code editor.

Tip

You can write key-value pairs to the $EXEC_OUTPUT file to pass data to other resources.

echo "STATUS=completed" >> $EXEC_OUTPUT

Choosing an execution mode

By default, the exec resource runs in local mode on the host machine. To run the script remotely, you can either:

• Specify an image to create a new container for execution.
• Set a target to run the script inside an existing container.

Note

The Remote (existing resource) option is only available when your lab already contains a container resource. You must create a container before you can target it for remote execution.

Editing an Exec resource

To edit an exec resource, select it from the list of existing sandboxes in the Sandbox tab. Click on the exec resource you want to edit, make your changes in the configuration panel, and then click Add changes to save your updates.

Configuration

General

Field	Required?	Default	Description
Script	✓		Script content to execute
Timeout		300s	Maximum execution time (Go duration string)
Environment			Key-value pairs for environment variables

Local execution

These fields are only available when running in local mode (no image or target specified).

Field	Required?	Default	Description
Working Directory			Working directory for script execution
Daemon		false	Run the script as a background daemon process

Remote execution (new container)

These fields are available when specifying an image to create a new container.

Image

Field	Required?	Default	Description
Name	✓		Docker image name with tag

Network

Field	Required?	Default	Description
Network ID	✓		Reference to a network resource
IP Address			Static IP address (auto-assigned if not set)
Aliases			Network aliases for the container

Note

Networks must be created before they can be assigned to an exec resource. For more information on creating a network resource, please refer to the Network documentation.

Volume

Field	Required?	Default	Description
Source	✓		Source path or volume name
Destination	✓		Mount path inside the container
Read Only		false	Mount the volume as read-only

Run as

Field	Required?	Default	Description
User	✓		Username or UID
Group	✓		Group name or GID

Remote execution (existing container)

Field	Required?	Default	Description
Target	✓		Reference to an existing container resource

Summary

The Exec resource provides flexible script execution capabilities for automating setup tasks, system configuration, and custom workflows in your lab sandbox. You can run scripts locally on the host or remotely inside containers — either by creating a new container from an image or by targeting an existing one.

With support for environment variables, output capture, timeouts, and advanced container options like volumes, networks, and user configuration, exec resources give you fine-grained control over your lab’s automation without needing to write configuration files.