Nest

Nest is the meltcloud management appliance that hosts Foundry and the Kubernetes control planes.

Components

Nest is made up of the following components:

• Foundry, a web process offering a web UI, the API & background jobs to manage the Kubernetes control planes and workers.
• The Kubernetes control planes (consisting of kube-apiserver, etcd and other components) run containerized to use resources efficiently
• Regular package updates for all involved components (control planes, worker nodes, management appliance) are retrieved via automated release channels.
• All involved components are remotely monitored by meltcloud.
• Important data – such as etcds and the Foundry database – are periodically backed up to a user-configured backup location (S3 bucket) for disaster recovery purposes.

Foundry

Foundry is meltcloud's management plane and the brain on the Nest:

It's made up of the web UI, the API and the background jobs that make everything work behind the scenes. It builds Enrollment Images, creates Clusters, rolls out Machine Revisions, hands out addresses from IP Pools and coordinates with the agents on every Machine.

Physical vs Virtual Appliance

Nest comes as either physical or virtual appliance:

1. Physical Appliance on meltcloud-provided hardware: We offer preconfigured hardware appliances to be installed on-premises.
2. Physical Appliance on customer-provided hardware: The customer uses its usual server vendor to spec servers to run Nest. This allows to reuse existing vendor partnerships, processes and monitoring tools.
3. Virtual Appliance: For trials/PoCs or when virtualized environments are preferred, Nest can also be run as virtual machines.

TIP

Want to try meltcloud without installing Nest in your DC?

Check out our SaaS option where Nest is hosted by us.

Airgapped Scenarios

Nest can also run in an airgapped fashion without requiring external connectivity. Be aware that this requires syncing the remote meltcloud packages to your OCI registry and integrating with your own monitoring stack.

Background: Why an Appliance?

When running Kubernetes on bare metal, a problem comes up quickly: modern servers are too powerful to use for just a control plane node. Most servers start with at least 256GB of RAM (and can go up to several terabytes), while a control plane usually needs only 4–64GB. This makes dedicating a full server to it quite wasteful.

Projects like Kamaji or Hypershift have come up with a smart approach: Hosted control planes, where the Kubernetes control planes itself are hosted within Kubernetes.

However, this introduces another challenge, the classic Bootstrap Problem: In an empty data center, how to create the first Kubernetes cluster to host the control planes?

A management appliance like Nest addresses both challenges:

• Solves the bootstrap problem by providing an initial Kubernetes cluster on the appliance
• Hosts the control planes for subsequent clusters

On top of that, it also runs Foundry, giving users a central place to deploy and manage their clusters.