Container

A Container resource lets you create and configure Docker containers that make up your lab environment. Containers provide the compute layer of your sandbox, allowing you to run applications, services, and tools that participants will use during hands-on exercises.

Through the UI, you can define container settings such as the image, startup commands, exposed ports, and environment variables, all without needing to write configuration files. You can also connect containers to networks, manage how they interact within the lab, and make them accessible through terminal tabs for users to interact with directly.

Containers make it easy to design flexible, interactive environments that replicate real-world systems and support a wide range of lab scenarios.

Where do setup scripts go?

To run a setup or initialization script in a container, add a separate Exec resource from Sandbox → + → Exec. Enter your script, choose Remote (existing resource), and select the container as the target.

The Container form’s Health Check → Exec → Script field is only for checking container health, not for setup scripts.

Creating a Container resource

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

Start by naming the container. Note that this is an internal name. You can assign a variety of settings to your container, but you also have the option to use a preset. Presets are pre-configured images for common container setups that can help you get started quickly. You can choose a preset from the Select preset dropdown menu:

Alternatively, you can select your own public or private image. By selecting “Add a new public or private image on GCP” you can add a custom image in the input.

Editing a container resource

To edit a container resource, you can select it from the list of existing sandboxes in the Sandbox tab. Click on the container you want to edit, make your changes in the configuration panel, and then click Add changes to save your updates. See Editing & Publishing for how changes are reviewed and published.

Form sections

The container form is organized into collapsible sections. The Image and Resources sections are expanded by default. All other sections are collapsed and can be expanded by clicking on them.

1. Image (expanded by default)

Field	Required?	Default	Description
Image	✓		Docker image for the container

Selecting a custom image, rather than a preset, also reveals Username and Password fields for pulling from a private registry.

2. Network (collapsed, optional)

You can attach a container to one or more networks. Each attachment has its own set of fields:

Field	Required?	Default	Description
ID	✓		Select the network to attach the container to
IP Address			Static IP address for the container on that network
Aliases			Alternate names for the container on that network

Note

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

3. Resources (expanded by default)

Field	Required?	Default	Description
CPU Limit		1000	CPU limit for the container
Memory Limit		256	Memory limit in MB
Disk Limit			Disk space limit in MB
CPU Pinning			Pin the container to one or more CPU cores
GPU Driver			GPU driver for the container
GPU Device IDs			GPU device IDs for the container
Max Restart Count			Maximum restart attempts (-1 for unlimited, 0 to disable restarts)

4. Entrypoint & Command (collapsed)

Field	Required?	Default	Description
Entrypoint			Override the default entrypoint
Command			Command to run in the container

This section also includes a Run As group to override the user and group the container runs as:

Field	Required?	Default	Description
User			Username or user ID to run the container as
Group			Group name or group ID to run the container as

Leave both fields empty to use the default user defined in the container image.

5. Environment Variables (collapsed)

Field	Required?	Default	Description
Environment Variables			Key-value pairs for environment variables

6. Labels (collapsed)

Field	Required?	Default	Description
Labels			Key-value pairs set on the container

7. DNS Servers (collapsed)

Field	Required?	Default	Description
DNS Servers			Custom DNS servers for the container

8. Port (collapsed)

Each port entry supports the following fields:

Field	Required?	Default	Description
Local Port	✓		Port the app listens on inside the container
Host Port			Optional host port to bind
Protocol		tcp	Protocol type: tcp or udp

9. Port Range (collapsed)

Field	Required?	Default	Description
Range	✓		Consecutive port range to expose (e.g. 8080-8090)
Enable Host		false	Expose the port range on the host
Protocol		tcp	Protocol type: tcp or udp

10. Volume (collapsed)

Field	Required?	Default	Description
Source	✓		Source path on the host machine
Destination	✓		Destination path inside the container
Type			Mount type: bind, volume, or tmpfs
Read Only		false	Mount the volume as read-only
Bind Propagation			Propagation mode for bind mounts: shared, private, slave, rslave, or rprivate
SELinux Relabel			SELinux relabeling mode: shared or private

11. Health Check (collapsed, optional)

Field	Required?	Default	Description
Timeout		30s	Health check timeout

You can add any number of HTTP, TCP, and Exec health checks. Each type is its own list, so a container can have several checks of the same type at once.

HTTP

Field	Required?	Default	Description
Address	✓		Healthcheck URL
Method		GET	HTTP method
Body			Request body
Headers			HTTP headers
Success Codes		200	Expected success codes

TCP

Field	Required?	Default	Description
Address	✓		Healthcheck address

Exec

Field	Required?	Default	Description
Command			Healthcheck command
Script			Healthcheck script
Exit Code		0	Expected exit code

The health check script is a probe that decides whether the container is healthy - it is not for setup or lifecycle scripting. To run setup scripts against a container, create an Exec resource targeting it.

12. Capabilities (collapsed, optional)

Field	Required?	Default	Description
Privileged			Run the container in privileged mode
Add			Add Linux capabilities to the container
Drop			Drop Linux capabilities from the container

Summary

The Container resource serves as the core compute component of your sandbox, enabling you to run the applications, services, and tools used in hands-on labs. You can easily create and configure containers through the UI by choosing a preset image or defining your own, setting startup commands, ports, and environment variables, all without writing configuration files.

For more granular control, containers can also be fine-tuned using advanced configuration options such as volumes, health checks, networks, and resource limits.

Overall, container resources make it simple to build flexible, interactive environments that closely replicate real-world systems and provide an engaging learning experience.