Adding Pod Disruption Budgets (PDB) to Java Chart (#41)

* Adding PDB for chart

README.md

@@ -86,6 +86,9 @@ The following table lists the configurable parameters of the Java chart and thei
 | `secrets`                  | Mappings of environment variables to service objects or pre-configured kubernetes secrets |  nil |
 | `keyVaults`                | Mappings of keyvaults to be mounted as flexvolumes (see Example Configuration) |  nil |
 | `applicationInsightsInstrumentKey` | Instrumentation Key for App Insights , It is mapped to `AZURE_APPLICATIONINSIGHTS_INSTRUMENTATIONKEY` as environment variable | `00000000-0000-0000-0000-000000000000`
+| `pdb.enabled` | To enable PodDisruptionBudget on the pods for handling disruptions | `true` |
+| `pdb.maxUnavailable` |  To configure the number of pods from the set that can be unavailable after the eviction. It can be either an absolute number or a percentage. pdb.minAvailable takes precedence over this if not nil | `50%` means evictions are allowed as long as no more than 50% of the desired replicas are unhealthy. It will allow disruption if you have only 1 replica.|
+| `pdb.minAvailable` |  To configure the number of pods from that set that must still be available after the eviction, even in the absence of the evicted pod. minAvailable can be either an absolute number or a percentage. This takes precedence over pdb.maxUnavailable if not nil. | `nil`|
 
 ## Adding Azure Key Vault Secrets
 Key vault secrets can be mounted to the container filesystem using what's called a [keyvault-flexvolume](https://github.com/Azure/kubernetes-keyvault-flexvol). A flexvolume is just a kubernetes volume from the user point of view. This means that the keyvault secrets are accessible as files after they have been mounted.

java/Chart.yaml

@@ -1,7 +1,7 @@
 apiVersion: v1
 description: A Helm chart for HMCTS Java Microservices
 name: java
-version: 1.1.1
+version: 1.1.2
 icon: https://github.com/hmcts/chart-java/raw/master/images/icons8-java-50.png
 keywords:
 - java

java/templates/pdb.yaml

@@ -0,0 +1,16 @@
+{{ if .Values.pdb.enabled }}
+---
+apiVersion: policy/v1beta1
+kind: PodDisruptionBudget
+metadata:
+  name:  {{ template "hmcts.releaseName" . }}
+spec:
+  {{ if .Values.pdb.minAvailable }}
+  minAvailable: {{ .Values.pdb.minAvailable }}
+  {{- else -}}
+  maxUnavailable: {{ .Values.pdb.maxUnavailable }}
+  {{- end }}
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: {{ template "hmcts.releaseName" . }}
+{{- end }}

java/values.yaml

@@ -18,3 +18,6 @@ livenessPeriod: 15
 livenessFailureThreshold: 3
 applicationInsightsInstrumentKey: '00000000-0000-0000-0000-000000000000'
 useInterpodAntiAffinity: false
+pdb:
+  enabled: true
+  maxUnavailable: 50%