Microservice kubernetes deployment + persistent logs gathering

Agenda

1.To show you how to deploy microservices on kubernetes
2.Configure gateway to expose microservices via ingress

Steps to run this project

Step 1

cd ms1
mvn clean install
docker build -t k8ms1:latest .
cd ../ms2
mvn clean install
docker build -t k8ms2:latest .
cd ../

Above code will help you in building docker images k8ms1 & k8ms2

Step 2

Push this docker images to docker registry

docker tag <id> <docker-registry-userid>/<repository>:<tag>
docker push <docker-registry-userid>/<repository>:<tag>

replace with container id that you could get by running

docker image ls --all

Step 3

cd deployment 
kubectl apply -f deployment-with-pvc.yaml

above command will create MS1 & MS2 microservices deployment with replica-set value 2 that means it will create two pods.

In deployment-with-pvc.yaml file i have mentioned volumeMounts that means MS2 /tmp/app.log will be map with the persistentVolumeClaim. ######[please read concept of persistentVolume & persistentVolumeClaim first]

volumeMounts:
            - mountPath: "/tmp/logs"
              name: k8ms2-mt-volume
      volumes:
        - name: k8ms2-mt-volume
          persistentVolumeClaim:
            claimName: task-pv-claim

Step 4

Create Gateway & virtual Service. You have to define the list of api's you want to expose

kubectl apply -f k8-gateway.yaml

In k8-gateway.yaml we are creating Gateway and in this i am using istio - ingressgateway

You have to set up istio service-mesh first , refer [http://istio.io/]

selector:
    istio: ingressgateway

For testing i am using minikube. You have to create persistant volume first

minikube ssh
sudo mkdir /mnt/data
exit

Then run below command

kubectl apply -f https://k8s.io/examples/pods/storage/pv-volume.yaml

pv-volume.yaml will command kubernetes to create PersistentVolume of capacity 10GB with ReadWriteOnce permission. Ideally in production environemnt, Administrator will provide you PersistentVolume which your pod will share by PersistentVolumeClaim .

apiVersion: v1
   kind: PersistentVolume
   metadata:
     name: task-pv-volume
     labels:
       type: local
   spec:
     storageClassName: manual
     capacity:
       storage: 10Gi
     accessModes:
       - ReadWriteOnce
     hostPath:
       path: "/mnt/data"

Let's create PersistentVolumeClaim

kubectl apply -f https://k8s.io/examples/pods/storage/pv-claim.yaml

pv-claim.yaml is a request to get 3GB disk resource with ReadWriteOnce accessModes.

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: task-pv-claim
spec:
  storageClassName: manual
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 3Gi

Let's test our application.

echo $(minikube ip):$(kubectl -n istio-system get service istio-ingressgateway -o jsonpath='{.spec.ports[?(@.name=="http2")].nodePort}')

Output 
192.168.99.103:31380

Open browser and hit [ http://192.168.99.103:31380/api2] you will get web page with hello message.

Invoke [http://192.168.99.103:31380/invoke3rdparty/api2] it will invoke 3rd party test api in this api code i have added some random logic to prove that in case you deploy this service with replication factor >1 then you will get merged logs of each container in persistant volume

minikube ssh 
cd /mnt/data 
ls -lrt 

Output 
app.log

Above app.log contains merged logs of each pod.

This would not be the best scenario to capture Logs in Kubernetes environment. Open for discussion :) Refer [https://kubernetes.io/docs/concepts/cluster-administration/logging/] for Logging architecture in k8