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Arsolitt
5786afe8bf
**What this PR does**
Adds configurable kubelet resource reservations and eviction thresholds
for tenant cluster worker nodes. Without explicit reservations and
cgroup enforcement, the scheduler treats nearly all node memory and CPU
as allocatable. Under pressure, the OOM killer can target kubelet itself
because no cgroup boundaries protect it, leading to "Kubelet stopped
posting node status" failures and unrecoverable NotReady nodes.
This PR auto-computes per-node-group kubelet reservations from the
effective node capacity (instanceType or explicit `resources`):
- **Memory**: `systemReservedMemory` and `kubeReservedMemory` each
default to 5% of effective memory, clamped 256Mi-1Gi
- **CPU**: `systemReservedCpu` and `kubeReservedCpu` each default to 5%
of effective CPU, clamped 50m-500m
- **Eviction**: configurable `evictionHardMemory` (default 7%) and
`evictionSoftMemory` (default 10%) with validation that hard < soft
- **Disk eviction**: `nodefs.available`, `imagefs.available`, and
`nodefs.inodesFree` thresholds are preserved alongside memory signals
- **Capacity annotations**: cluster-autoscaler annotations now report
allocatable memory and CPU (total minus all reservations and eviction
threshold) instead of raw totals
- **Cgroup enforcement**: `enforce-node-allocatable=pods` configures
advisory-only reservations — the scheduler accounts for reserved
resources when computing allocatable capacity, but no cgroup boundaries
are enforced for system or kube reserved resources
- **Validation**: format checks, zero-value rejection, eviction ordering
(hard < soft), same-unit-type requirement for eviction thresholds, and
total reservation sanity check against effective node capacity
All reservation fields are optional and overridable per node group via
`.nodeGroups[].kubelet`.
**Default rendered kubeletExtraArgs:**
```yaml
kubeletExtraArgs:
system-reserved: "memory=256Mi,cpu=50m"
kube-reserved: "memory=256Mi,cpu=50m"
eviction-hard: "memory.available<7%,nodefs.available<10%,imagefs.available<15%,nodefs.inodesFree<5%"
eviction-soft: "memory.available<10%,nodefs.available<15%,imagefs.available<20%"
eviction-soft-grace-period: "memory.available=1m30s,nodefs.available=1m30s,imagefs.available=1m30s"
eviction-minimum-reclaim: "memory.available=256Mi"
enforce-node-allocatable: "pods"
```
**New values schema:**
```yaml
nodeGroups:
md0:
kubelet:
systemReservedMemory: "" # auto-computed (5% of effective memory, 256Mi-1Gi)
kubeReservedMemory: "" # auto-computed (5% of effective memory, 256Mi-1Gi)
systemReservedCpu: "" # auto-computed (5% of effective CPU, 50m-500m)
kubeReservedCpu: "" # auto-computed (5% of effective CPU, 50m-500m)
evictionHardMemory: "7%" # absolute (e.g. 200Mi) or percentage
evictionSoftMemory: "10%" # must be > evictionHardMemory, same unit type
```
**Release note:**
```
feat(kubernetes): add per-node-group kubelet resource reservations with auto-computed system/kube reserved memory (5% of effective memory, clamped 256Mi-1Gi) and CPU (5% of effective CPU, clamped 50m-500m), configurable memory eviction thresholds, preserved disk eviction signals (nodefs, imagefs, inodesFree), pods-only cgroup enforcement, and reservation-aware allocatable capacity annotations for cluster-autoscaler.
```