AWS ALB Ingress Service - Context Path Based Routing

Step-01: Introduction

• Discuss about the Architecture we are going to build as part of this Section
• We are going to create two more apps with static pages in addition to UMS.
• App1 with context as /app1 - Simple Nginx custom built image
• App2 with context as /app2 - Simple Nginx custom built image
• We are going to deploy all these 3 apps in kubernetes with context path based routing enabled in Ingress Controller
• /app1/* - should go to app1-nginx-nodeport-service
• /app2/* - should go to app1-nginx-nodeport-service
• /* - should go to sermgmt-restapp-nodeport-service
• As part of this process, this respective annotation alb.ingress.kubernetes.io/healthcheck-path: /usermgmt/health-status will be moved to respective application NodePort Service. Only generic settings will be present in Ingress manifest annotations area 07-ALB-Ingress-ContextPath-Based-Routing.yml
• Refer Presentation from slide 106 onwards

Kubernetes Manifests

01

#01-MySQL-externalName-Service.yml
apiVersion: v1
kind: Service
metadata:
  name: mysql
spec:
  type: ExternalName
  externalName: usermgmtdb.cxojydmxwly6.us-east-1.rds.amazonaws.com

02

#02-UserManagementMicroservice-Deployment-Service.yml
apiVersion: apps/v1
kind: Deployment 
metadata:
  name: usermgmt-microservice
  labels:
    app: usermgmt-restapp
spec:
  replicas: 1
  selector:
    matchLabels:
      app: usermgmt-restapp
  template:  
    metadata:
      labels: 
        app: usermgmt-restapp
    spec:
      initContainers:
        - name: init-db
          image: busybox:1.31
          command: ['sh', '-c', 'echo -e "Checking for the availability of MySQL Server deployment"; while ! nc -z mysql 3306; do sleep 1; printf "-"; done; echo -e "  >> MySQL DB Server has started";']      
      containers:
        - name: usermgmt-restapp
          image: stacksimplify/kube-usermanagement-microservice:1.0.0  
          ports: 
            - containerPort: 8095           
          env:
            - name: DB_HOSTNAME
              value: "mysql"            
            - name: DB_PORT
              value: "3306"            
            - name: DB_NAME
              value: "usermgmt"            
            - name: DB_USERNAME
              value: "dbadmin"        # RDS DB Username is dbadmin     
            - name: DB_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: mysql-db-password
                  key: db-password           
          livenessProbe:
            exec:
              command: 
                - /bin/sh
                - -c 
                - nc -z localhost 8095
            initialDelaySeconds: 60
            periodSeconds: 10
          readinessProbe:
            httpGet:
              path: /usermgmt/health-status
              port: 8095
            initialDelaySeconds: 60
            periodSeconds: 10          

03

#03-Kubernetes-Secrets.yml
apiVersion: v1
kind: Secret
metadata:
  name: mysql-db-password
type: Opaque
data: 
  db-password: ZGJwYXNzd29yZDEx

04

#04-UserManagement-NodePort-Service.yml
apiVersion: v1
kind: Service
metadata:
  name: usermgmt-restapp-nodeport-service
  labels:
    app: usermgmt-restapp
  annotations:
#Important Note:  Need to add health check path annotations in service level if we are planning to use multiple targets in a load balancer  
    alb.ingress.kubernetes.io/healthcheck-path: /usermgmt/health-status    
spec:
  type: NodePort
  selector:
    app: usermgmt-restapp
  ports:
    - port: 8095
      targetPort: 8095

05

#05-Nginx-App1-Deployment-and-NodePortService.yml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: app1-nginx-deployment
  labels:
    app: app1-nginx
spec:
  replicas: 1
  selector:
    matchLabels:
      app: app1-nginx
  template:
    metadata:
      labels:
        app: app1-nginx
    spec:
      containers:
        - name: app1-nginx
          image: stacksimplify/kube-nginxapp1:1.0.0
          ports:
            - containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
  name: app1-nginx-nodeport-service
  labels:
    app: app1-nginx
  annotations:
#Important Note:  Need to add health check path annotations in service level if we are planning to use multiple targets in a load balancer    
    alb.ingress.kubernetes.io/healthcheck-path: /app1/index.html
spec:
  type: NodePort
  selector:
    app: app1-nginx
  ports:
    - port: 80
      targetPort: 80

06

#06-Nginx-App2-Deployment-and-NodePortService.yml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: app2-nginx-deployment
  labels:
    app: app2-nginx 
spec:
  replicas: 1
  selector:
    matchLabels:
      app: app2-nginx
  template:
    metadata:
      labels:
        app: app2-nginx
    spec:
      containers:
        - name: app2-nginx
          image: stacksimplify/kube-nginxapp2:1.0.0
          ports:
            - containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
  name: app2-nginx-nodeport-service
  labels:
    app: app2-nginx
  annotations:
#Important Note:  Need to add health check path annotations in service level if we are planning to use multiple targets in a load balancer
    alb.ingress.kubernetes.io/healthcheck-path: /app2/index.html
spec:
  type: NodePort
  selector:
    app: app2-nginx
  ports:
    - port: 80
      targetPort: 80

07

#07-ALB-Ingress-ContextPath-Based-Routing.yml
# Annotations Reference:  https://kubernetes-sigs.github.io/aws-alb-ingress-controller/guide/ingress/annotation/
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: ingress-usermgmt-restapp-service
  labels:
    app: usermgmt-restapp
  annotations:
    # Ingress Core Settings
    kubernetes.io/ingress.class: "alb"
    alb.ingress.kubernetes.io/scheme: internet-facing
    # Health Check Settings
    alb.ingress.kubernetes.io/healthcheck-protocol: HTTP 
    alb.ingress.kubernetes.io/healthcheck-port: traffic-port
#Important Note:  Need to add health check path annotations in service level if we are planning to use multiple targets in a load balancer    
    #alb.ingress.kubernetes.io/healthcheck-path: /usermgmt/health-status
    alb.ingress.kubernetes.io/healthcheck-interval-seconds: '15'
    alb.ingress.kubernetes.io/healthcheck-timeout-seconds: '5'
    alb.ingress.kubernetes.io/success-codes: '200'
    alb.ingress.kubernetes.io/healthy-threshold-count: '2'
    alb.ingress.kubernetes.io/unhealthy-threshold-count: '2'
spec:
  rules:
    - http:
        paths:
          - path: /app1/*
            backend:
              serviceName: app1-nginx-nodeport-service
              servicePort: 80                        
          - path: /app2/*
            backend:
              serviceName: app2-nginx-nodeport-service
              servicePort: 80            
          - path: /*
            backend:
              serviceName: usermgmt-restapp-nodeport-service
              servicePort: 8095              
# Important Note-1: In path based routing order is very important, if we are going to use  "/*", try to use it at the end of all rules.         

Step-02: Create Nginx App1 & App2 Deployment & Service

• App1 Nginx: 05-Nginx-App1-Deployment-and-NodePortService.yml
• App2 Nginx: 06-Nginx-App2-Deployment-and-NodePortService.yml

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Step-03: Update Health Check Path Annotation in User Management Node Port Service

• Health check path annotation should be moved to respective node port services if we have to route to multiple targets using single load balancer.
• 04-UserManagement-NodePort-Service.yml

  #Important Note:  Need to add health check path annotations in service level if we are planning to use multiple targets in a load balancer  
      alb.ingress.kubernetes.io/healthcheck-path: /usermgmt/health-status  
  

Step-04: Create ALB Ingress Context path based Routing Kubernetes manifest

• 07-ALB-Ingress-ContextPath-Based-Routing.yml

  # Annotations Reference:  https://kubernetes-sigs.github.io/aws-alb-ingress-controller/guide/ingress/annotation/
  apiVersion: extensions/v1beta1
  kind: Ingress
  metadata:
    name: ingress-usermgmt-restapp-service
    labels:
      app: usermgmt-restapp
    annotations:
      # Ingress Core Settings
      kubernetes.io/ingress.class: "alb"
      alb.ingress.kubernetes.io/scheme: internet-facing
      # Health Check Settings
      alb.ingress.kubernetes.io/healthcheck-protocol: HTTP 
      alb.ingress.kubernetes.io/healthcheck-port: traffic-port
  #Important Note:  Need to add health check path annotations in service level if we are planning to use multiple targets in a load balancer    
      #alb.ingress.kubernetes.io/healthcheck-path: /usermgmt/health-status
      alb.ingress.kubernetes.io/healthcheck-interval-seconds: '15'
      alb.ingress.kubernetes.io/healthcheck-timeout-seconds: '5'
      alb.ingress.kubernetes.io/success-codes: '200'
      alb.ingress.kubernetes.io/healthy-threshold-count: '2'
      alb.ingress.kubernetes.io/unhealthy-threshold-count: '2'
  spec:
    rules:
      - http:
          paths:
            - path: /app1/*
              backend:
                serviceName: app1-nginx-nodeport-service
                servicePort: 80                        
            - path: /app2/*
              backend:
                serviceName: app2-nginx-nodeport-service
                servicePort: 80            
            - path: /*
              backend:
                serviceName: usermgmt-restapp-nodeport-service
                servicePort: 8095              
  # Important Note-1: In path based routing order is very important, if we are going to use  "/*", try to use it at the end of all rules.                         
  

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Step-05: Deploy all manifests and test

• Deploy

  kubectl apply -f kube-manifests/
  

• Verify ingress resource got created

  # List Ingress Load Balancers
  kubectl get ingress
  
  # List Pods
  kubectl get pods
  
  # List Services
  kubectl get svc
  

• Verify ALB Ingress Controller Logs

  # Verify logs
  kubectl logs -f $(kubectl get po -n kube-system | egrep -o 'alb-ingress-controller-[A-Za-z0-9-]+') -n kube-system
  

• We should not see anything like below log in ALB Ingress Controller, if we see we did something wrong with ALB Ingress Controleer deployment primarily in creating IAM Policy, Service Account & Role and Associating Role to Service Account.

07:28:39.900001       1 controller.go:217] kubebuilder/controller "msg"="Reconciler error" "error"="failed to build LoadBalancer configuration due to unable to fetch subnets. Error: WebIdentityErr: failed to retrieve credentials\ncaused by: AccessDenied: Not authorized to perform sts:AssumeRoleWithWebIdentity\n\tstatus code: 403, request id: 3d54741a-4b85-4025-ad11-73d4a3661d09"  "controller"="alb-ingress-controller" "request"={"Namespace":"default","Name":"ingress-usermgmt-restapp-service"}

- Verify Application Load Balancer on AWS Management Console - Verify Load Balancer - In Listeners Tab, click on View/Edit Rules under Rules - Verify Target Groups - GroupD Details - Targets: Ensure they are healthy - Verify Health check path - Verify all 3 targets are healthy)

• Access Application

  http://<ALB-DNS-URL>/app1/index.html
  http://<ALB-DNS-URL>/app2/index.html
  http://<ALB-DNS-URL>/usermgmt/health-status
  

Step-06: Clean Up

kubectl delete -f kube-manifests/

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