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Prefix

A Prefix resource provides a fully integrated IP address management(IPAM) solution for Ironcore. It serves as a means to define IP prefixes along with prefix length to a reserved range of IP addresses. It is also possible to define child prefixes with the specified prefix length referring to the parent prefix.

Example Volume Resource

An example of how to define a root Prefix resource in Ironcore

apiVersion: ipam.ironcore.dev/v1alpha1
kind: Prefix
metadata:
  name: root
  labels:
    root-prefix: customer-1
spec:
  prefix: 10.0.0.0/24
An example of how to define a child Prefix resource in Ironcore

apiVersion: ipam.ironcore.dev/v1alpha1
kind: Prefix
metadata:
  name: child-prefix
spec:
  ipFamily: IPv4
  prefixLength: 9
  parentSelector:
    matchLabels:
      root-prefix: customer-1
(Note: Refer to E2E Examples for more detailed example on IPAM to understant e2e flow)

Key Fields:

  • ipFamily(string): ipFamily is the IPFamily of the prefix. If unset but prefix is set, this can be inferred.

  • prefix (string): prefix is the IP prefix to allocate for this Prefix.

  • prefixLength (int): prefixLength is the length of prefix to allocate for this Prefix.

  • parentRef (string): parentRef references the parent to allocate the Prefix from. If parentRef and parentSelector is empty, the Prefix is considered a root prefix and thus allocated by itself.

  • parentSelector (LabelSelector): parentSelector is the LabelSelector to use for determining the parent for this Prefix.

Reconciliation Process:

  • Allocate root prefix: If parentRef and parentSelector is empty, the PrefixController reconciler considers it as a root prefix and allocates by itself and the status is updated as Allocated.

  • Allocating sub-prefix: If parentRef or parentSelector is set PrefixController lists all the previously allocated prefix allocations by parent prefix. Finds all the active allocations and prunes outdated ones. If no existing PrefixAllocation object is found new PrefixAllocation object is created for the new prefix to allocate. If prefix allocation is successful status is updated to Allocated otherwise to Failed.

  • Prefix allocation scheduler: PrefixAllocationScheduler continuously watches for Prefix resource and tries to schedule all PrefixAllocation objects for which prefix is not yet allocated. PrefixAllocationScheduler determines suitable prefix for allocation by listing available prefixes based on label filter, namespace and desired IP family. Once a suitable prefix is found PrefixAllocation spec.parentRef is updated with the selected prefix reference.

  • Status update: Once prefix allocation is successful status is updated to Allocated. In the case of sub-prefixes once the prefix is allocated PrefixController updates the parent Prefix's status with the used prefix IPs list.

Below is the sample Prefix.status :

status:
  lastPhaseTransitionTime: "2024-10-21T20:56:24Z"
  phase: Allocated
  used:
  - 10.0.0.1/32
  - 10.0.0.2/32