Handle inconsistent zone naming
timuthy opened this issue · comments
How to categorize this issue?
/area high-availability
/area control-plane
/kind enhancement
/platform azure
What would you like to be added:
A new webhook should be added to the Azure provider extension that reacts on Pod creations and mutates node affinities that contain zone information.
The logic is supposed to prefix the zone by the shoot's region, like shown in the following example where the shoot is located in westeurope.
Input:
spec:
affinity:
nodeAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
nodeSelectorTerms:
- matchExpressions:
- key: topology.kubernetes.io/zone
operator: In
values:
- "2"
Output:
spec:
affinity:
nodeAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
nodeSelectorTerms:
- matchExpressions:
- key: topology.kubernetes.io/zone
operator: In
values:
- "westeurope-2"
Why is this needed:
Gardener expects a consistent zone naming across shoot and seed clusters.
When ManagedSeed workers are configured shoot.spec.provider.workers[].zones, the very same information is replicated to seed.spec.provider.zones. This is furthermore used to add node affinities to control-plane pods in the seed (see this document for more information).
Azure however, has an inconsistent naming in this matter and breaks the expectation. While zones are officially numeric only (1, 2, 3, ...), the CCM adds a compound of region + zone to the related node label, i.e. topology.kubernetes.io/zone: {region}-{zone}
Refs (thanks @kon-angelo):