/jdg-rolling-demo

Primary LanguageJava

jdg-rolling-demo

This application is intended to demo rolling update and failover functionality of JBoss Data Grid in OpenShift. The deployment consists of two components

How to run

  • Clone the repository
  • Use oc login to log to an OpenShift instance
  • Deploy the application
oc process -v PROJECT_NAMESPACE=<project> -f template/jdg-rolling.yaml -o yaml| oc create -f -
  • Configure the service account for JDG cache
oc policy add-role-to-user admin system:serviceaccount:$(oc project -q):jdg-service-account -n $(oc project -q)

The role admin is used because we need role view for clustering and an access to a resource pods/proxy for imporoved readiness probe.

Components

Improved readiness probe

We need to enhance the readiness probe to marke the pod to be ready only after the initial state transfer is completed. Tis information is available only via JMX in JDG 6.5. To get this information we are using embedded Jolokia to query the required MBean. This means we need access to the pods/proxy resource. JDG 7.0 exposes the necessary information over JBoss DMR so a plain http call to DMR REST endpoint will be sufficient in future,

Client application

The client application is a Spring Boot application using Infinispan Spring Boot Starter to confiure the connection between the application and the remote cache. The application itself exposes four REST endpoints

  • /single/write
  • /single/read
  • /bulk/write
  • /bulk/read

Demo workflow

  • Run stern to monitor client application pod logs
stern -n ... 'jdg-client-app-*'

Dying cache instances

  • Start writing to cache from two client application instances
curl -v 'http://jdg-client-app-<host>/bulk/write?from=0&count=25000'
curl -v 'http://jdg-client-app-<host>/bulk/write?from=100000&count=25000'
  • Kill all JDG pods but one with command oc delete pod datagrid-app-... --grace-period=0
  • When writing is finished verify the contents of the cache using
curl -v 'http://jdg-client-app-<host>/bulk/read?from=100000&count=25000'
curl -v 'http://jdg-client-app-<host>/bulk/read?from=0&count=25000'

Cache redeployment

  • Start writing to cache from two client application instances
curl -v 'http://jdg-client-app-<host>/bulk/write?from=200000&count=25000'
curl -v 'http://jdg-client-app-<host>/bulk/write?from=300000&count=25000'
  • Trigger an update of JDG instance oc deploy datagrid-app --latest
  • When writing is finished verify the contents of the cache using
curl -v 'http://jdg-client-app-<host>/bulk/read?from=300000&count=25000'
curl -v 'http://jdg-client-app-<host>/bulk/read?from=200000&count=25000'