spring-camel-cluster-singleton

Camel based cluster singleton service using camel's core FileLockClusterService or KubernetesClusterService.

Camel Leader Election using config based ClusterService

Based on blog article post: https://www.nicolaferraro.me/2017/10/17/creating-clustered-singleton-services-on-kubernetes/

Original gitlab link: https://github.com/nicolaferraro/spring-camel-cluster-singleton.git

The app at the moment support file and kubernetes based Cluster Service implementations.

Enable File Cluster Service

Service: FileLockClusterService

Config: Camel Cluster Service

First comment kubernetes based config lines in application.properties if there are present then set/uncomment the file lock based clustering like this:

camel.component.file.cluster.service.enabled = true
camel.component.file.cluster.service.id = ${random.uuid}
camel.component.file.cluster.service.root = ${java.io.tmpdir}
camel.component.file.cluster.service.cluster-labels[group]=${project.groupId}
camel.component.file.cluster.service.cluster-labels[app]=${project.artifactId}

Enable Kubernetes Cluster Service

First comment file based clustering lines in application.properties if there are present then set/uncomment the kubernetes based clustering like this:

camel.component.kubernetes.cluster.service.enabled=true
camel.component.kubernetes.cluster.service.cluster-labels[group]=${project.groupId}
camel.component.kubernetes.cluster.service.cluster-labels[app]=${project.artifactId}

Deploy to kubernetes wih command:

Check if minikube already running, start it if not already started: minikube start

kubectl apply -f src/main/fabric8/raw/rb.yml kubectl apply -f src/main/fabric8/raw/role.yml kubectl apply -f src/main/fabric8/raw/sa.yml

eval $(minikube docker-env) mvn fabric8:deploy For the above programs use the same terminal session otherwise you will be phasing image pull error in kubernetes

Check the cluster singleton service in the logs:

To configure endpoints

The master service endpoint uri format is the following:

master:namespace:delegateUri

Where you can define any endpoint, queue, timer, etc

The above consuming jms foo endpoint and delegates to other queue: from("master:lock1:jms:foo").to("activemq:wine")

See: ClasterRoutes.java

Choose Cluster Service based on environment

By default file based cluster leader election is enabled, setting config to:

camel.component.file.cluster.service.enabled = true

To enable kubernetes cluster service you should disable file based cluster and enable kubernetes config:

camel.component.kubernetes.cluster.service.enabled=true

Testing

Set the environment variables, file lock or kubernetes

Testing on kubernetes

If you are using minikube execute: minikube start then: eval $(minikube docker-env) Configure kubectl, run command mvn fabric8:deploy

Use kubernetes command: Kubectl cheet sheet: https://kubernetes.io/docs/reference/kubectl/cheatsheet/

• kubectl get pods,
• kubectl logs
• kubectl delete pod
• kubectl get deployments
• kubectl delete deployment