MetalKube Documentation

The MetalKube project exists to provide components that allow you to do bare metal host management for Kubernetes. MetalKube works as a Kubernetes application, meaning it runs on Kubernetes and is managed through Kubernetes interfaces.

Operators are a key piece of the MetalKube architecture as the method used to manage kubernetes applications.

MetalKube Component Overview

Machine API Integration

Another set of components is being designed and built to provide integration with the Kubernetes Machine API.

This first diagram represents the high level architecture:

Machine API Actuator

The first component is the Bare Metal Actuator. This is the component with logic specific to this architecture for handling changes to the lifecycle of Machine objects. This actuator may be integrated with the existing Machine API Operator or some other implementation of the cluster API.

This actuator will associate Machine objects with a bare metal host from the inventory of bare metal hosts managed by the Bare Metal Operator.

Bare Metal Operator

The architecture also includes a new Bare Metal Operator, which includes the following:

• A Controller for a new Custom Resource, BareMetalHost. This custom resource represents an inventory of known (configured or automatically discovered) bare metal hosts. When a Machine is created the Bare Metal Actuator will claim one of these hosts to be provisioned as a new Kubernetes node.
• In response to BareMetalHost updates, will perform bare metal host provisioning actions as necessary to reach the desired state. It will do so by managing and driving a set of underlying bare metal provisioning components.
• The implementation will focus on using Ironic as its first implementation of the Bare Metal Management Pods, but aims to keep this as an implementation detail under the hood such that alternatives could be added in the future if the need arises.

The creation of the BareMetalHost inventory can be done in two ways:

1. Manually via creating BareMetalHost objects.
2. Optionally, automatically created via a bare metal host discovery process. Ironic is capable of doing this, which will also be integrated into MetalKube as an option.

APIs

1. Enroll nodes by creating BareMetalHost resources. This would either be manually or done by a component doing node discovery and introspection.

   See the documentation in the baremetal-operator repository for details.

2. Use the machine API to allocate a machine.

apiVersion: "cluster.k8s.io/v1alpha1"
kind: Machine
metadata:
    generateName: baremetal-master-
    labels:
        set: master
spec:
    providerSpec:
        value:
            apiVersion: "baremetalproviderconfig/v1alpha1"
            kind: "BareMetalProviderConfig"
            selector:
                node-profile: master


apiVersion: "cluster.k8s.io/v1alpha1"
kind: Machine
metadata:
    generateName: baremetal-node-
    labels:
          set: node
spec:
    providerSpec:
        value:
            apiVersion: "baremetalproviderconfig/v1alpha1"
            kind: "BareMetalProviderConfig"
            selector:
                node-profile: node

3. Machine is associated with an available BareMetalHost, which triggers provisioning of that host to join the cluster. (Exact mechanism for this association is TBD).