Reset default system reserved resources to previous defaults.

Author: davidumea

changelog/2.27.0.md

@@ -42,3 +42,6 @@ Released 2025-03-24
 - [#420](https://github.com/elastisys/compliantkubernetes-kubespray/pull/420) - documentation: Update Ubuntu 24.04 migration guide to include instructions for UpCloud @Ajarmar
 - [#424](https://github.com/elastisys/compliantkubernetes-kubespray/pull/424) - documentation: Fix LICENSE @cristiklein
 - [#427](https://github.com/elastisys/compliantkubernetes-kubespray/pull/427) - Kept previous Calico version `v3.27` due to newer versions being incompatible with Calico-Accountant
+- [#427](https://github.com/elastisys/compliantkubernetes-kubespray/pull/427) - Reset default system reserved resources to previous defaults.
+    - Increased kube reserved memory on worker nodes from `256Mi` to `512Mi`.
+    - Decreased kube reserved cpu on control plane nodes from `200m` to `100m`.

config/common/group_vars/k8s_cluster/ck8s-k8s-cluster.yaml

@@ -123,6 +123,11 @@ local_volume_provisioner_storage_classes: # Installation via kubespray has no su
     host_dir: /mnt/disks/
     mount_dir: /mnt/disks/
 
+kube_memory_reserved: "512Mi"
+kube_cpu_reserved: "100m"
+system_cpu_reserved: "0m"
+system_memory_reserved: "0Mi"
+
 audit_policy_custom_rules: |-
   # The following requests were manually identified as high-volume and low-risk,
   # so drop them.

migration/v2.27/prepare/30-reserved-resources.sh

@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+
+HERE="$(dirname "$(readlink -f "${0}")")"
+ROOT="$(readlink -f "${HERE}/../../../")"
+
+# shellcheck source=scripts/migration/lib.sh
+source "${ROOT}/scripts/migration/lib.sh"
+
+# Usage: update_reserved_resources <sc|wc>
+function update_reserved_resources() {
+  cluster="${1}"
+
+  log_info "Updating reserved resources for ${cluster}"
+
+  kubespray_config_path="${CK8S_CONFIG_PATH}/${cluster}-config/group_vars/k8s_cluster/ck8s-k8s-cluster.yaml"
+
+  yq4 -i '.kube_memory_reserved = "512Mi"' "${kubespray_config_path}"
+  yq4 -i '.kube_cpu_reserved = "100m"' "${kubespray_config_path}"
+  yq4 -i '.system_cpu_reserved = "0m"' "${kubespray_config_path}"
+  yq4 -i '.system_memory_reserved = "0Mi"' "${kubespray_config_path}"
+}
+
+if [[ "${CK8S_CLUSTER}" =~ ^(sc|both)$ ]]; then
+  update_reserved_resources sc
+fi
+if [[ "${CK8S_CLUSTER}" =~ ^(wc|both)$ ]]; then
+  update_reserved_resources wc
+fi