Compute Resources

Machine

A Machine resource in IronCore is used to represent a compute resource or a virtual machine. It serves as a means to configure network, storage, type of machine and other information needed to create a compute instance.

Example Machine Resource

An example of how to define a Machine resource:

apiVersion: compute.ironcore.dev/v1alpha1
kind: Machine
metadata:
  name: machine-sample
spec:
  machineClassRef:
    name: machineclass-sample
  image: my-image
  volumes:
    - name: rootdisk # first disk is the root disk
      volumeRef:
        name: my-volume
  networkInterfaces:
    - name: primary
      networkInterfaceRef:
        name: networkinterface-sample
  ignitionRef:
    name: my-ignition-secret

Key Fields:

• machineClassRef (string): Is a reference to the MachineClass of the machine.
• machinePoolRef (string): Defines the MachinePool to run the Machine on. If empty, the IronCore scheduler will figure out an appropriate pool to run the Machine on.
• image (string): Image is the optional URL providing the operating system image to memory boot the Machine. A detailed description of OS images can be found the corresponding section.
• volumes (list): Are list of Volumes attached to this machine. Here the first volume is considered as the root disk. Each volume is defined with a name and a reference to the Volume resource.
• networkInterfaces (list): Define a list of network interfaces present on the machine.
• ignitionRef (string): Is a reference to a secret containing the ignition YAML for the machine to boot up. If the key value is empty, the DefaultIgnitionKey=ignition will be used as a fallback.

Reconciliation Process

1. Machine Scheduling: The MachineScheduler controller continuously watches for Machines without an assigned MachinePool and tries to schedule it on available and matching MachinePool.

• Monitor Unassigned Machines: The scheduler continuously watches for machines without an assigned machinePoolRef.
• Retrieve Available Machine Pools: The scheduler fetches the list of available machine pools from the cache.
• Make Scheduling Decisions: The scheduler selects the most suitable machine pool based on resource availability and other policies.
• Update Cache: The scheduler updates the cache with recalculated allocatable machineClass quantities.
• Assign MachinePoolRef: The scheduler assigns the selected machinePoolRef to the machine object.

More information on how the IRI contract works can be found in the IronCore Runtime Interface (IRI) section.

4. Network Interface handling: MachineControllerNetworkinterface takes care of attaching/detaching NetworkInterfaces defined for the Machine. Once the attachment is successful status is updated from Pending to Attached.

5. Volume handling: MachineControllerVolume takes care of attach/detach of Volumes defined for a Machine. Once the attachment is successful status is updated from Pending to Attached.

6. Ephemeral resource handling:

• The Volume and NetworkIntreface can be bound with the lifecycle of the Machine by creating them as ephemeral resources. (Note: For more details on how to create ephemeral resources refer to Machine with ephemeral resources)
• If a NetworkIntreface or a Volume is defined as ephemeral MachineEphemeralControllers takes care of creating and destroying respective objects on creation/deletion of the machine.

Lifecycle and States

A Machine can be in the following states:

1. Pending: A Machine is in a Pending state when the Machine has been accepted by the system, but not yet completely started. This includes time before being bound to a MachinePool, as well as time spent setting up the Machine on that MachinePool.
2. Running: A Machine in Running state when the machine is running on a MachinePool.
3. Shutdown: A Machine is in a Shutdown state.
4. Terminating: A Machine is Terminating.
5. Terminated: A Machine is in the Terminated state when the machine has been permanently stopped and cannot be started.

MachineClass

A MachineClass is an IronCore resource used to represent a class/flavor of a Machine. It serves as a means to define the number of resources a Machine object can have as capabilities (e.g. CPU, memory) associated with a particular class.

Example Machine Resource

An example of how to define a MachineClass resource:

apiVersion: compute.ironcore.dev/v1alpha1
kind: MachineClass
metadata:
  name: machineclass-sample
capabilities:
  cpu: 4
  memory: 16Gi

Key Fields:

• capabilities (ResourceList): capabilities are used to define a list of resources a Machine can have along with its capacity.

MachinePool

A MachinePool is a resource in IronCore that represents a pool of compute resources managed collectively. It defines the infrastructure's compute configuration used to provision and manage Machines, ensuring resource availability and compatibility with associated MachineClasses. (Note: One machinepoollet is responsible for one MachinePool)

Details on how Pools are announced and used can be found in the Pools and Poollets section.

Example MachinePool Resource

An example of how to define a MachinePool resource:

apiVersion: compute.ironcore.dev/v1alpha1
kind: MachinePool
metadata:
  name: machinepool-sample
spec:
  providerID: ironcore://shared

Key Fields:

• ProviderID(string): The providerId helps the controller identify and communicate with the correct compute system within the specific backend compute provider.