To deploy EasyAppoinments web app onto a kubernetes cluster: a). clone this repo ("https://github.com/putical/k8s-easyappointments.git") on a kubernetes cluster master node b). CD into the directory 'k8s-easyappointments', then run command 'kubectl apply -f ./' to deploy the app
Note: this method is to deploy 'EasyAppointments' app for a sample client, after run the above command, below items will be deployed onto the kubernetes cluster: (yaml files are templates)
- two pods (one for application, the other for DB instance)
- two deployments objects (one for application, the other for DB instance)
- two services objects (one for application, the other for DB instance)
- a ConfigMap object (stores the environment variables for both containers, for this example, there are sensitive information like DB passwords stored in the file which is not secure. Ideally, sensitive information should be saved into 'secret' objects' and pods decrypte those credentials when start up from mounted volumes
- two persistent volumes (one for application, the other for DB instance)
- two persistent volume claims (one for application persistent volume, the other for DB persistent volume)
A possible solution to automate application deployment for different clients: To differentiate deployments between different clients, names of pods/deployment/services/pvc/pv need to be different, this can be achieved by changing the name attribute under 'metadata' in each yaml file and host mount paths for App and DB persistent volumes.
To automate it, a simple bash script with a series of 'sed' commands can be used to do content search & replace against those yaml template files. When there are new clients to be added, run the script with the client name as argument.
example deployments outputs would be like this:
sgao@master:~/k8s-easyappointments$ kubectl get pods NAME READY STATUS RESTARTS AGE application-clientA-6499ff5dcb-7kc6z 1/1 Running 0 28m database-clientA-59c4678566-bd46b 1/1 Running 0 28m application-clientB-3829ba4fad-8tyuc 1/1 Running 0 50m database-clientB-4323gi4ihy-hn94c 1/1 Running 0 50m
sgao@master:~/k8s-easyappointments$ kubectl get deployments NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE application-clientA 1 1 1 1 28m database-clientA 1 1 1 1 28m application-clientB 1 1 1 1 50m database-clientB 1 1 1 1 50m
sgao@master:~/k8s-easyappointments$ kubectl get svc NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE application-clientA ClusterIP 10.104.205.100 80/TCP 28m database-clientA ClusterIP None 55555/TCP 28m application-clientB ClusterIP 10.104.205.101 80/TCP 50m database-clientB ClusterIP None 55555/TCP 50m kubernetes ClusterIP 10.96.0.1 443/TCP 27h
sgao@master:~/k8s-easyappointments$ kubectl get pv NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE application-ClientA-pv 1Gi RWO Retain Bound default/easy-appointments-data 29m db-ClientA-pv 1Gi RWO Retain Bound default/easy-appointments-storage 29m application-ClientB-pv 1Gi RWO Retain Bound default/easy-appointments-data 51m db-ClientB-pv 1Gi RWO Retain Bound default/easy-appointments-storage 51m