K8s - Microservice

Microservice

In this lab, we will use example provided by DickyChesterwood. The docker images are available on Docker Hub

The scenario as shown in the above diagram. The deployment steps are:

1. Queue (ActiveMQ)

First of all we will create active-mq.yaml

# ActiveMQ Deployment
apiVersion: apps/v1
kind: Deployment
metadata:
  name: queue
spec:
  selector:
    matchLabels:
      app: queue
  replicas: 1
  template: 
    metadata:
      labels:
        app: queue
    spec:
      containers:
      - name: queue
        image: richardchesterwood/k8s-fleetman-queue:release1

---
# ActiveMQ Service
apiVersion: v1
kind: Service
metadata:
  name: fleetman-queue

spec:
  # This defines which pods are going to be represented by this Service
  # The service becomes a network endpoint for either other services
  # or maybe external users to connect to (eg browser)
  selector:
    app: queue

  ports:
    - name: http
      port: 8161
      nodePort: 30010

    - name: endpoint
      port: 61616

  type: NodePort

kubectl apply -f active-mq.yaml

Now open in browser http://192.168.59.105:30010/

ActiveMQ default username/password is admin/admin

2. Position Tracker

apiVersion: apps/v1
kind: Deployment
metadata:
  name: position-tracker
spec:
  selector:
    matchLabels:
      app: position-tracker
  replicas: 1
  template: # template for the pods
    metadata:
      labels:
        app: position-tracker
    spec:
      containers:
      - name: position-tracker
        image: richardchesterwood/k8s-fleetman-position-tracker:release1
        env:
        - name: SPRING_PROFILES_ACTIVE
          value: production-microservice
---
apiVersion: v1
kind: Service
metadata:
  name: fleetman-position-tracker

spec:
  # This defines which pods are going to be represented by this Service
  # The service becomes a network endpoint for either other services
  # or maybe external users to connect to (eg browser)
  selector:
    app: position-tracker

  ports:
    - name: http
      port: 8080
      nodePort: 30011

  type: NodePort

When we hit through browser to http://192.168.59.105:30011/ we get 404 which means that the position tracker service (spring boot app) run well.

For checking purpose we can let the position tracker as NodePort. For production purpose, we can consider to change the NodePort to ClusterIP since position tracker microservice is not designed to be accessed from ouside cluster.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: position-tracker
spec:
  selector:
    matchLabels:
      app: position-tracker
  replicas: 1
  template: # template for the pods
    metadata:
      labels:
        app: position-tracker
    spec:
      containers:
      - name: position-tracker
        image: richardchesterwood/k8s-fleetman-position-tracker:release1
        env:
        - name: SPRING_PROFILES_ACTIVE
          value: production-microservice
---
apiVersion: v1
kind: Service
metadata:
  name: fleetman-position-tracker

spec:
  # This defines which pods are going to be represented by this Service
  # The service becomes a network endpoint for either other services
  # or maybe external users to connect to (eg browser)
  selector:
    app: position-tracker

  ports:
    - name: http
      port: 8080
      #nodePort: 30011

  #type: NodePort
  type: ClusterIP

3. Position Simulator

In the diagram, the position simulator is not designed to be accessed from outside the cluster. So it should be isolated and no port needed.

# Position Simulator Deployment
apiVersion: apps/v1
kind: Deployment
metadata:
  name: position-simulator
spec:
  selector:
    matchLabels:
      app: position-simulator
  replicas: 1
  template: # template for the pods
    metadata:
      labels:
        app: position-simulator
    spec:
      containers:
      - name: position-simulator
        image: richardchesterwood/k8s-fleetman-position-simulator:release1
        env:
        - name: SPRING_PROFILES_ACTIVE
          value: production-microservice

Save the above yaml as position-simulator.yaml and run apply command.

kubectl apply -f position-simulator.yaml

Once the position simulator running, we should see queue record in the ActiveMQ dashboard.

4. API Gateway

apiVersion: apps/v1
kind: Deployment
metadata:
  name: api-gateway
spec:
  selector:
    matchLabels:
      app: api-gateway
  replicas: 1
  template: # template for the pods
    metadata:
      labels:
        app: api-gateway
    spec:
      containers:
      - name: api-gateway
        image: richardchesterwood/k8s-fleetman-api-gateway:release1
        env:
        - name: SPRING_PROFILES_ACTIVE
          value: production-microservice

---
apiVersion: v1
kind: Service
metadata:
  name: fleetman-api-gateway

spec:
  # This defines which pods are going to be represented by this Service
  # The service becomes a network endpoint for either other services
  # or maybe external users to connect to (eg browser)
  selector:
    app: api-gateway

  ports:
    - name: http
      port: 8080
      nodePort: 30020

  type: NodePort

Let’s check the API gateway by open http://192.168.59.105:30020/ in browser.

5. Webapp

apiVersion: apps/v1
kind: Deployment
metadata:
  name: webapp
spec:
  selector:
    matchLabels:
      app: webapp
  replicas: 1
  template: # template for the pods
    metadata:
      labels:
        app: webapp
    spec:
      containers:
      - name: webapp
        image: richardchesterwood/k8s-fleetman-webapp-angular:release1
        env:
        - name: SPRING_PROFILES_ACTIVE
          value: production-microservice

---
apiVersion: v1
kind: Service
metadata:
  name: fleetman-webapp

spec:
  # This defines which pods are going to be represented by this Service
  # The service becomes a network endpoint for either other services
  # or maybe external users to connect to (eg browser)
  selector:
    app: webapp

  ports:
    - name: http
      port: 80
      nodePort: 30080

  type: NodePort

Let’s review all microservice deployments before we open the app.

Lastly we can open the app in browser http://192.168.59.105:30080/

Investigating Kubernates Log

If we get an error on resource we can chek

# get pod description including kubernetes message while creating/updating the pod
kubectl describe pod position-simulator-56686f95f8-tb6zt

# get the application log (spring log)
kubectl logs api-gateway-5bf5cfc887-9gtwv
kubectl logs position-simulator-56686f95f8-tb6zt

# get the application log by following the log
kubectl logs -f position-simulator-56686f95f8-tb6zt

References

https://github.com/DickChesterwood/k8s-fleetman/tree/release0-reconstruction-branch
https://www.nginx.com/blog/microservices-at-netflix-architectural-best-practices/

kubernetes