Add Node Health Check (#62)

Author: rbo

.mdl_style.rb

@@ -12,3 +12,4 @@
 exclude_rule 'MD033'
 exclude_rule 'MD007'
 rule 'MD003', :style => :atx
+rule 'MD029', :style => :ordered

content/kubevirt/node-health-check.md

@@ -0,0 +1,88 @@
+---
+title: Node Health Check
+linktitle: Node Health Check
+description: OpenShift Virtualization - Fencing and VM High Availability Guide
+tags: ["kubevirt","ocp-v","cnv"]
+---
+# Node Health Check
+
+## Resources
+
+* [OpenShift Virtualization - Fencing and VM High Availability Guide](https://access.redhat.com/articles/7057929)
+
+## Installation & configuration
+
+* Install Operator "Node Health Check Operator"
+
+### Start operator for worker nodes
+
+``` { .yaml .annotate }
+apiVersion: remediation.medik8s.io/v1alpha1
+kind: NodeHealthCheck
+metadata:
+  name: worker-availability
+spec:
+  minHealthy: 51%
+  remediationTemplate:
+    apiVersion: self-node-remediation.medik8s.io/v1alpha1
+    kind: SelfNodeRemediationTemplate
+    name: self-node-remediation-automatic-strategy-template
+    namespace: openshift-workload-availability
+  selector:
+    matchExpressions:
+      - key: node-role.kubernetes.io/worker
+        operator: Exists
+        values: []
+  unhealthyConditions:
+    - duration: 1s # (1)!
+      status: 'False'
+      type: Ready
+    - duration: 1s # (2)!
+      status: Unknown
+      type: Ready
+```
+
+1. Change the seconds to achieve the fasted VM recovery, according to [OpenShift Virtualization - Fencing and VM High Availability Guide](https://access.redhat.com/articles/7057929#test-results-9)
+2. Change the seconds to achieve the fasted VM recovery, according to [OpenShift Virtualization - Fencing and VM High Availability Guide](https://access.redhat.com/articles/7057929#test-results-9)
+
+### Update `self-node-remediation-automatic-strategy-template`
+
+``` { .yaml .hl_lines="13" .annotate }
+apiVersion: self-node-remediation.medik8s.io/v1alpha1
+kind: SelfNodeRemediationTemplate
+metadata:
+  annotations:
+    remediation.medik8s.io/multiple-templates-support: "true"
+  labels:
+    remediation.medik8s.io/default-template: "true"
+  name: self-node-remediation-automatic-strategy-template
+  namespace: openshift-workload-availability
+spec:
+  template:
+    spec:
+      remediationStrategy: OutOfServiceTaint # (1)!
+```
+
+1. Default is "Automatic", but I want a predictable behavor. [Offical documentation](https://docs.redhat.com/en/documentation/workload_availability_for_red_hat_openshift/23.2/html-single/remediation_fencing_and_maintenance/index#about-self-node-remediation-operator_self-node-remediation-operator-remediate-nodes)
+
+    ```bash
+    $ oc explain SelfNodeRemediationTemplate.spec.template.spec.remediationStrategy
+    GROUP:      self-node-remediation.medik8s.io
+    KIND:       SelfNodeRemediationTemplate
+    VERSION:    v1alpha1
+
+    FIELD: remediationStrategy <string>
+
+    DESCRIPTION:
+        RemediationStrategy is the remediation method for unhealthy nodes.
+        Currently, it could be either "Automatic", "OutOfServiceTaint" or
+        "ResourceDeletion".
+        ResourceDeletion will iterate over all pods and VolumeAttachment related to
+        the unhealthy node and delete them.
+        OutOfServiceTaint will add the out-of-service taint which is a new
+        well-known taint "node.kubernetes.io/out-of-service"
+        that enables automatic deletion of pv-attached pods on failed nodes,
+        "out-of-service" taint is only supported on clusters with k8s version 1.26+
+        or OCP/OKD version 4.13+.
+        Automatic will choose the most appropriate strategy during runtime.
+    ```

mkdocs.yml

@@ -236,6 +236,7 @@ nav:
 
   - OpenShift Virtualization:
       - kubevirt/index.md
+      - Node Health Check: kubevirt/node-health-check.md
       - Templates: kubevirt/template.md
       - Ansible: kubevirt/ansible/README.md
       - Networking: kubevirt/networking.md