Templates
Templates are the foundation of Knot. They define reusable environment configurations that users can deploy as spaces with a single click. Think of templates as blueprints for development environments, complete with compute resources, storage, networking, and tooling.
What is a Template?
A template defines:
- Platform: Where the environment runs (Nomad cluster, Docker, Podman, Apple Container, or KVM virtual machines)
- Container specification: The image, environment variables, and runtime configuration
- Volumes: Persistent storage that survives space restarts
- Resources: CPU, memory, and storage allocations
- Features: Enabled capabilities like SSH, web terminal, or Code Server
- Access control: Which groups can use the template
- Custom variables: User-defined values set when creating a space
Available Platforms
Admins can restrict which backends templates may use with the server’s --enabled-backends flag (KNOT_ENABLED_BACKENDS, config server.enabled_backends): a list of manual, docker, podman, apple, nomad and kvm. Empty (the default) offers everything — manual included. A non-empty list must name everything it wants offered, manual included: ["docker"] disables manual templates too, ["docker", "manual"] keeps them. The template editor only shows offered platforms — with a single container backend enabled it shows that backend as a plain option instead of the Local Container dropdown.
The list also sets the auto-detection order for Local Container templates: container backends are probed in the order listed, so --enabled-backends podman,docker makes Podman the auto-detected runtime when both are available. (This flag replaced the former --local-container-runtime-pref.)
This is a policy allowlist, separate from runtime detection: a listed backend still needs a node that can run it (see runtime availability). Existing templates on a since-disabled platform stay editable but can’t be switched to another disabled one, and new templates can’t use it.
Template Types
KVM Templates Run spaces as full virtual machines on KVM-capable nodes, booted from cloud images with bridged or NAT networking. Best for workloads that need their own kernel, systemd, or non-container toolchains. See KVM Templates.
Nomad Templates Run in a Nomad cluster using HCL job specifications. Best for production deployments with high availability and scalability.
Docker/Podman Templates Run on local machines or single servers using container runtimes. Ideal for individual developers or small teams.
Apple Container Templates Run on macOS using Apple’s native container runtime. Perfect for macOS-specific development.
Manual Templates For environments where you manually start the knot agent. Useful for physical machines or custom setups.
Volume Lifecycle
Understanding how volumes work is critical:
- Space creation: All volumes defined in the template are created
- Space start/stop: Volumes persist and retain all data
- Space deletion: All volumes and their data are permanently removed
- Template updates: If volumes are removed from a template, they are deleted when the space next starts
Deleting a space permanently destroys all volumes and data. Always backup important data before deletion.
Storage Systems
Nomad Templates Use Container Storage Interface (CSI) plugins for flexible storage options including network storage, local storage, and cloud provider volumes.
Local Container Templates Use the native volume system of Docker, Podman, or Apple Container for local persistent storage.
Common Use Cases
- Development environments: Pre-configured with languages, tools, and dependencies
- Testing environments: Isolated spaces for QA with specific configurations
- Training environments: Consistent setups for workshops or onboarding
- Demo environments: Quick deployment of product demos
- CI/CD runners: Ephemeral build and test environments