Implement application health check and hpa

Signed-off-by: Ashwani Singh <ashwani.singh@opstree.com>

charts/microservice/Chart.yaml

@@ -1,9 +1,27 @@
----
 apiVersion: v2
 name: microservice
 description: A Helm chart for a microservice in Kubernetes
+
+# A chart can be either an 'application' or a 'library' chart
+#
+# Application chart deploys a complete application, includes all necessary Kubernetes resources, 
+# used for installing and managing applications.
+#
+# Library chart provides reusable templates and components, does not deploy an application by itself, 
+# used to promote consistency and reuse across multiple charts.
 type: application
+
+# This is the chart version. This chart version should be incremented with each change to the chart 
+# or its templates, including the app version. 
+# Follow Semantic Versioning (https://semver.org/). 
 version: 0.1.2
+
+# This is the application version number, which should be incremented with each change to the application. 
+# It doesn't need to follow Semantic Versioning but should reflect the application's version. 
+# Quotes are recommended.
 appVersion: "0.1.2"
+
+# This is maintainers files. this field lists the individuals or teams responsible for maintaining the Helm chart. 
+# It typically includes their names and contact information, such as email addresses.
 maintainers:
   - name: Opstree Solutions

charts/microservice/README.md

@@ -25,9 +25,9 @@ helm install my-release microservice/
 
 ## TODO
 
-- [ ] Application Health Probes
+- [x] Application Health Probes
 - [ ] Service
-- [ ] Horizontal Pod Autoscaler
+- [x] Horizontal Pod Autoscaler
 - [ ] ConfigMap
 - [ ] RBAC 
   - [ ] Service Account

charts/microservice/templates/_helpers.tpl

@@ -5,20 +5,20 @@ Create  a defautl fully qualified app name
 It will use the release name to give the app name
 */}}
 
-{{- define "app.name" -}}
-{{- default .Chart.Name .Values.nameOverride | trunc 60 | trimSuffix "-" }}
+{{- define "microservice.name" -}}
+{{- default .Values.global.nameOverride | trunc 60 | trimSuffix "-" }}
 {{- end }}
 
 {{/*
 Create a default fully qualified app name.
 We truncate at 63 chars because some Kubernetes name fields are limited to this (by the DNS naming spec).
 If release name contains chart name it will be used as a full name.
 */}}
-{{- define "app.tempname" -}}
-{{- if .Values.fullnameOverride }}
-{{- .Values.fullnameOverride | trunc 60 | trimSuffix "-" }}
+{{- define "microservice.tempname" -}}
+{{- if .Values.global.fullnameOverride }}
+{{- .Values.global.fullnameOverride | trunc 60 | trimSuffix "-" }}
 {{- else }}
-{{- $name := default .Chart.Name .Values.nameOverride }}
+{{- $name := default .Values.global.nameOverride }}
 {{- if contains $name .Release.Name }}
 {{- .Release.Name | trunc 63 | trimSuffix "-" }}
 {{- else }}
@@ -27,34 +27,41 @@ If release name contains chart name it will be used as a full name.
 {{- end }}
 {{- end }}
 
-{{- define "app.fullname" -}}
-{{- printf "%s-%s" ( include "app.tempname" . ) "app" | trunc 63 | trimSuffix "-" }}
+{{- define "microservice.fullname" -}}
+{{- printf "%s-%s" ( include "microservice.tempname" . ) "app" | trunc 63 | trimSuffix "-" }}
 {{- end }}
 
 {{/*
 Common labels
 */}}
-{{- define "app.labels" -}}
-app: {{ include "app.tempname" . }}
+{{- define "microservice.labels" -}}
+app: {{ include "microservice.tempname" . }}
 {{- end }}
 
 {{/*
 Selector labels
 */}}
-{{- define "app.selectorLabels" -}}
-app: {{ include "app.tempname" . }}
+{{- define "microservice.selectorLabels" -}}
+app: {{ include "microservice.tempname" . }}
 {{- end }}%
 
 {{/*
 service name
 */}}
-{{- define "app.servicename" -}}
-{{- printf "%s-%s" ( include "app.tempname" . ) "svc" | trunc 63 | trimSuffix "-" }}
+{{- define "microservice.servicename" -}}
+{{- printf "%s-%s" ( include "microservice.tempname" . ) "svc" | trunc 63 | trimSuffix "-" }}
 {{- end }}%
 
 {{/*
 configmap name
 */}}
-{{- define "app.configmapname" -}}
-{{- printf "%s-%s" ( include "app.tempname" . ) "cm" | trunc 63 | trimSuffix "-" }}
+{{- define "microservice.configmapname" -}}
+{{- printf "%s-%s" ( include "microservice.tempname" . ) "cm" | trunc 63 | trimSuffix "-" }}
+{{- end }}%
+
+{{/*
+Create name of the HPA to use 
+*/}}
+{{- define "microservice.HorizontalScalingName" -}}
+{{- printf "%s-%s" ( include "microservice.tempname" . ) "hpa" | trunc 63 | trimSuffix "-" }}
 {{- end }}%

charts/microservice/templates/deployment.yaml

@@ -1,24 +1,48 @@
 apiVersion: apps/v1
 kind: Deployment
 metadata:
-  name: {{ include "app.fullname" . }}
+  name: {{ include "microservice.fullname" . }}
   labels:
-    {{- include "app.labels" . | nindent 4 }}
+    {{- include "microservice.labels" . | nindent 4 }}
 spec:
-  replicas: {{ .Values.replicaCount }}
+  replicas: {{ .Values.global.replicaCount }}
   selector:
     matchLabels:
-      {{- include "app.selectorLabels" . | nindent 6 }}
+      {{- include "microservice.selectorLabels" . | nindent 6 }}
   template:
     metadata:
       labels:
-        {{- include "app.selectorLabels" . | nindent 8 }}
+        {{- include "microservice.selectorLabels" . | nindent 8 }}
     spec:
       containers:
-        - name: {{ .Chart.Name }}
-          image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
-          imagePullPolicy: {{ .Values.image.pullPolicy }}
+        - name: {{ include "microservice.fullname" . }}
+          image: "{{ .Values.deployment.image.repository }}:{{ .Values.deployment.image.tag }}"
+          imagePullPolicy: {{ .Values.deployment.image.pullPolicy | default "IfNotPresent" }}
           ports:
             - name: http
               containerPort: 80
               protocol: TCP
+          {{- if .Values.deployment.livenessProbe }}
+          livenessProbe:
+            httpGet:
+              path: {{ default "/health" .Values.deployment.livenessProbe.httpPath }}
+              port: http
+            initialDelaySeconds: {{ default 25 .Values.deployment.livenessProbe.initialDelaySeconds }}
+            periodSeconds: {{ default 10 .Values.deployment.livenessProbe.periodSeconds }}
+            timeoutSeconds: {{ default 5 .Values.deployment.livenessProbe.timeoutSeconds }}
+            successThreshold: {{ default 1 .Values.deployment.livenessProbe.successThreshold }}
+            failureThreshold: {{ default 5 .Values.deployment.livenessProbe.failureThreshold }}
+          {{- end }}
+          {{- if .Values.deployment.readinessProbe }}
+          readinessProbe:
+            httpGet:
+              path: {{ default "/health" .Values.deployment.readinessProbe.httpPath }}
+              port: http
+            initialDelaySeconds: {{ default 25 .Values.deployment.readinessProbe.initialDelaySeconds }}
+            periodSeconds: {{ default 10 .Values.deployment.readinessProbe.periodSeconds }}
+            timeoutSeconds: {{ default 5 .Values.deployment.readinessProbe.timeoutSeconds }}
+            successThreshold: {{ default 1 .Values.deployment.readinessProbe.successThreshold }}
+            failureThreshold: {{ default 5 .Values.deployment.readinessProbe.failureThreshold }}
+          {{- end }}
+          resources:
+            {{- toYaml .Values.deployment.resources | nindent 12 }}          

charts/microservice/templates/hpa.yaml

@@ -0,0 +1,27 @@
+{{- if .Values.hpa }}
+apiVersion: autoscaling/v2beta1
+kind: HorizontalPodAutoscaler
+metadata:
+  name: {{ include "microservice.HorizontalScalingName" . }}
+  labels:
+    {{- include "microservice.labels" . | nindent 4 }}
+spec:
+  scaleTargetRef:
+    kind: Deployment
+    name: {{ include "microservice.fullname" . }}
+  minReplicas: {{ default 1 .Values.hpa.minReplicas }}
+  maxReplicas: {{ default 1 .Values.hpa.maxReplicas }}
+  metrics:
+  {{- if .Values.hpa.targetAverageCPUUtilization }}
+  - type: Resource
+    resource:
+      name: cpu
+      targetAverageUtilization: {{ default 50 .Values.hpa.targetAverageCPUUtilization }}
+  {{- end }}
+  {{- if .Values.hpa.targetAverageMemoryUtilization }}
+  - type: Resource
+    resource:
+      name: memory
+      targetAverageUtilization: {{ default 50 .Values.hpa.targetAverageMemoryUtilization }}
+  {{- end }}
+{{- end }}

charts/microservice/templates/service.yaml

@@ -1,9 +1,9 @@
 apiVersion: v1
 kind: Service
 metadata:
-  name: {{ include "app.servicename" . }}
+  name: {{ include "microservice.servicename" . }}
   labels:
-    {{- include "app.labels" . | nindent 4 }}
+    {{- include "microservice.labels" . | nindent 4 }}
 spec:
   type: {{ .Values.service.type }}
   ports:
@@ -12,4 +12,4 @@ spec:
       protocol: TCP
       name: http
   selector:
-    {{- include "app.selectorLabels" . | nindent 4 }}
+    {{- include "microservice.selectorLabels" . | nindent 4 }}

charts/microservice/values.yaml

@@ -1,12 +1,42 @@
-replicaCount: 1
+# -- global variables  
+global:
+  replicaCount: 1
+  fullnameOverride: "nginx"
+  nameOverride: ""
 
-fullnameOverride: "nginx"
-nameOverride: ""
-image:
-  repository: nginx
-  pullPolicy: IfNotPresent
-  tag: "latest"
+# -- Object that configures Deployment instance
+deployment:
+  # -- Override default container image format
+  image:
+    # -- Image repository
+    repository: "nginx"
+    # -- Image tag
+    tag: "latest"
+    # -- Variable used to control when the image should be fetched
+    pullPolicy: always
+  # -- Definition of the liveness probe
+  livenessProbe: 
+    httpPath: '/'
+  # -- Definition of the readiness probe
+  readinessProbe:
+    httpPath: '/'
+  # -- Configure container's resource request and limits
+  resources:
+    # -- Resources that the container is guaranteed to get
+    requests:
+      # -- Memory that the container is guaranteed to get
+      memory:
+      # -- CPU that the container is guaranteed to get
+      cpu: 
+    # -- Defines a hard ceiling on resource use
+    limits:
+      # -- Defines a hard ceiling on how much Memory time that the container can use
+      memory:
+      # -- Defines a hard ceiling on how much CPU time that the container can use
+      cpu:
+
+hpa: {}
 
 service:
   type: ClusterIP
-  port: 80
+  port: 80