# Jumpstarter Service

When building a lab with many devices under test, it quickly becomes difficult
to keep track of devices, schedule access for automated tests, and perform routine
tasks such as batch updates.

Jumpstarter provides a [Cloud Native](https://www.cncf.io/) service that can
be installed in any [Kubernetes](https://kubernetes.io/) cluster to manage
connected clients and exporters.

If you're already using a Kubernetes-native CI tool such as
[Tekton](https://tekton.dev/), [Jenkins X](https://jenkins-x.io/),
or [GitLab CI](https://docs.gitlab.com/ee/user/clusters/agent/ci_cd_workflow.html),
Jumpstarter can integrate directly into your existing cloud or on-prem cluster.

## Controller

The core of the Jumpstarter service is the Controller, which manages access to
devices, authenticates clients/exporters, and maintains a set of labels to easily
identify specific devices.

The Controller is implemented as a Kubernetes [controller](https://github.com/jumpstarter-dev/jumpstarter-controller)
using [Custom Resource Definitions (CRDs)](https://kubernetes.io/docs/concepts/extend-kubernetes/api-extension/custom-resources/)
to store information about clients, exporters, leases, etc.

### Leases

When a client requests access to an exporter and a matching instance is found, a
Lease is created. The lease ensures that each lesee (client) has exclusive
access to a specific device/exporter.

Clients can be scheduled to access a specific exporter or any exporter that matches
a set of requested labels, similar to [node selection](https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/#nodeselector)
in Kubernetes. This enable flexible CI-driven testing even when physical resources
are limited.

## Router

The Router service is used by the controller to route messages between
clients and exporters through a gRPC tunnel. This enables remote access to
exported interfaces via a the client.

Once a lease is established, all traffic between the client and the exporter
flows through a router instance. While there may only be one controller,
the router can be scaled to handle traffic from many clients/exporters
simultaneously.