JHipster-generated Kubernetes configuration

Preparation

You will need to push your image to a registry. If you have not done so, use the following commands to tag and push the images:

$ docker image tag jhipstersampleapplication yogi8demo/jhipstersampleapplication
$ jhipstersampleapplication yogi8demo/jhipstersampleapplication

Deployment

You can deploy all your apps by running the below bash command:

./kubectl-apply.sh

Exploring your services

Use these commands to find your application's IP addresses:

$ kubectl get svc jhipstersampleapplication

Scaling your deployments

You can scale your apps using

$ kubectl scale deployment <app-name> --replicas <replica-count>

zero-downtime deployments

The default way to update a running app in kubernetes, is to deploy a new image tag to your docker registry and then deploy it using

$ kubectl set image deployment/<app-name>-app <app-name>=<new-image>

Using livenessProbes and readinessProbe allow you to tell Kubernetes about the state of your applications, in order to ensure availablity of your services. You will need minimum 2 replicas for every application deployment if you want to have zero-downtime deployed. This is because the rolling upgrade strategy first kills a running replica in order to place a new. Running only one replica, will cause a short downtime during upgrades.

Monitoring tools

Prometheus metrics (setup giving error)

Generator is also packaged with Prometheus operator by CoreOS.

hint: use must build your apps with prometheus profile active!

Application metrics can be explored in Prometheus through,

$ kubectl get svc jhipster-prometheus

Also the visualisation can be explored in Grafana which is pre-configured with a dashboard view. You can find the service details by

$ kubectl get svc jhipster-grafana

• If you have chosen Ingress, then you should be able to access Grafana using the given ingress domain.
• If you have chosen NodePort, then point your browser to an IP of any of your nodes and use the node port described in the output.
• If you have chosen LoadBalancer, then use the IaaS provided LB IP

Troubleshooting

my apps doesn't get pulled, because of 'imagePullBackof'

Check the registry your Kubernetes cluster is accessing. If you are using a private registry, you should add it to your namespace by kubectl create secret docker-registry (check the docs for more info)

my applications get killed, before they can boot up

This can occur if your cluster has low resource (e.g. Minikube). Increase the initialDelySeconds value of livenessProbe of your deployments

my applications are starting very slow, despite I have a cluster with many resources

The default setting are optimized for middle-scale clusters. You are free to increase the JAVA_OPTS environment variable, and resource requests and limits to improve the performance. Be careful!

I have selected Prometheus but no targets are visible

This depends on the setup of the Prometheus operator and the access control policies in your cluster. Version 1.6.0+ is needed for the RBAC setup to work.

I have selected Prometheus, but my targets never get scraped

This means your applications are probably not built using the prometheus profile in Maven/Gradle

my SQL-based microservice is stuck during Liquibase initialization when running multiple replicas

Sometimes the database changelog lock gets corrupted. You will need to connect to the database using kubectl exec -it and remove all lines of liquibases databasechangeloglock table.