[Documentation] Replace Member procedure (#1800)

Author: ajanikow

chart/kube-arangodb-arm64/templates/webhook/mutation.yaml

@@ -38,5 +38,30 @@ webhooks:
     admissionReviewVersions: ["v1"]
     sideEffects: None
     timeoutSeconds: 5
+  - name: "generic.pod.policies.scheduler.arangodb.com"
+    namespaceSelector:
+      matchExpressions:
+        - key: kubernetes.io/metadata.name
+          operator: In
+          values:
+            - {{ .Release.Namespace }}
+    objectSelector:
+      matchExpressions:
+        - key: profiles.arangodb.com/apply
+          operator: Exists
+    rules:
+      - apiGroups:   [""]
+        apiVersions: ["v1"]
+        operations:  ["CREATE"]
+        resources:   ["pods"]
+        scope:       "Namespaced"
+    clientConfig:
+      service:
+        namespace: {{ .Release.Namespace }}
+        name: {{ template "kube-arangodb.operatorName" . }}-webhook
+        path: /webhook/core/v1/pods/policies/mutate
+    admissionReviewVersions: ["v1"]
+    sideEffects: None
+    timeoutSeconds: 5
 
 {{- end }}

chart/kube-arangodb-enterprise-arm64/templates/webhook/mutation.yaml

@@ -38,5 +38,30 @@ webhooks:
     admissionReviewVersions: ["v1"]
     sideEffects: None
     timeoutSeconds: 5
+  - name: "generic.pod.policies.scheduler.arangodb.com"
+    namespaceSelector:
+      matchExpressions:
+        - key: kubernetes.io/metadata.name
+          operator: In
+          values:
+            - {{ .Release.Namespace }}
+    objectSelector:
+      matchExpressions:
+        - key: profiles.arangodb.com/apply
+          operator: Exists
+    rules:
+      - apiGroups:   [""]
+        apiVersions: ["v1"]
+        operations:  ["CREATE"]
+        resources:   ["pods"]
+        scope:       "Namespaced"
+    clientConfig:
+      service:
+        namespace: {{ .Release.Namespace }}
+        name: {{ template "kube-arangodb.operatorName" . }}-webhook
+        path: /webhook/core/v1/pods/policies/mutate
+    admissionReviewVersions: ["v1"]
+    sideEffects: None
+    timeoutSeconds: 5
 
 {{- end }}

chart/kube-arangodb-enterprise/templates/webhook/mutation.yaml

@@ -38,5 +38,30 @@ webhooks:
     admissionReviewVersions: ["v1"]
     sideEffects: None
     timeoutSeconds: 5
+  - name: "generic.pod.policies.scheduler.arangodb.com"
+    namespaceSelector:
+      matchExpressions:
+        - key: kubernetes.io/metadata.name
+          operator: In
+          values:
+            - {{ .Release.Namespace }}
+    objectSelector:
+      matchExpressions:
+        - key: profiles.arangodb.com/apply
+          operator: Exists
+    rules:
+      - apiGroups:   [""]
+        apiVersions: ["v1"]
+        operations:  ["CREATE"]
+        resources:   ["pods"]
+        scope:       "Namespaced"
+    clientConfig:
+      service:
+        namespace: {{ .Release.Namespace }}
+        name: {{ template "kube-arangodb.operatorName" . }}-webhook
+        path: /webhook/core/v1/pods/policies/mutate
+    admissionReviewVersions: ["v1"]
+    sideEffects: None
+    timeoutSeconds: 5
 
 {{- end }}

chart/kube-arangodb/templates/webhook/mutation.yaml

@@ -38,5 +38,30 @@ webhooks:
     admissionReviewVersions: ["v1"]
     sideEffects: None
     timeoutSeconds: 5
+  - name: "generic.pod.policies.scheduler.arangodb.com"
+    namespaceSelector:
+      matchExpressions:
+        - key: kubernetes.io/metadata.name
+          operator: In
+          values:
+            - {{ .Release.Namespace }}
+    objectSelector:
+      matchExpressions:
+        - key: profiles.arangodb.com/apply
+          operator: Exists
+    rules:
+      - apiGroups:   [""]
+        apiVersions: ["v1"]
+        operations:  ["CREATE"]
+        resources:   ["pods"]
+        scope:       "Namespaced"
+    clientConfig:
+      service:
+        namespace: {{ .Release.Namespace }}
+        name: {{ template "kube-arangodb.operatorName" . }}-webhook
+        path: /webhook/core/v1/pods/policies/mutate
+    admissionReviewVersions: ["v1"]
+    sideEffects: None
+    timeoutSeconds: 5
 
 {{- end }}

docs/how-to/replace-pod.md

@@ -0,0 +1,25 @@
+---
+layout: page
+title: How to replace Pod
+parent: How to ...
+---
+
+# How to replace Pod
+
+Replacement of ArangoDeployment Pods can be triggered by annotation.
+
+Replacement of the pod will ensure that destruction of the member will never result in data loss.
+
+Replacement is disabled for:
+- Single Servers
+
+Replacement of member for particular groups will result in:
+- Agents - Member and PVC is recreated, Operator ensures that Quorum is kept during this operation
+- DBServers - New DBServer is added where data is migrated before removal
+- Coordinator, Gateway - Simple shutdown
+
+Key: `deployment.arangodb.com/replace`
+Value: `true`
+
+To rotate ArangoDeployment Pod kubectl command can be used:
+`kubectl annotate pod arango-pod deployment.arangodb.com/replace=true`