Overview

Current project includes a Proof of concept for a generic scalable policy engine. Policy engine is based on drools with rule kjars discovery in a remote maven repository. Messages are delivered at the policy engine workers based on consistent hashing technique.

Policy engine Arquitecture:

Current solution supports consistent hashing delivery of messages at policy manager workers:

Prerequisites:

1. Rabbitmq pub/sub framework with the https://github.com/rabbitmq/rabbitmq-consistent-hash-exchange enabled.
   You can access to http://localhost:15672 with username/password guest/guest.
   You should configure rabbitmq by ip at the application properties of policyengine

docker-compose up -d broker
docker exec broker rabbitmq-plugins enable rabbitmq_management
docker exec broker rabbitmq-plugins enable rabbitmq_consistent_hash_exchange

2. A Nexus maven repository

docker-compose up -d my-nexus //like this there is a connectivity problem between policy manager container and nexus
docker run -d -p 8081:8081 -p 8082:8082 -p 8083:8083 --name my-nexus sonatype/nexus3:3.0.0

You should create a new repository named maven-group that includes the following sub repositories: central, releases & snapshots.
Extra information can be found http://codeheaven.io/using-nexus-3-as-your-repository-part-1-maven-artifacts/
You can access Nexus repository at http://localhost:8081

You should update the ip of the remote nexus maven repository at the following files:

• settings.xml
• /src/main/resources/application.properties

Local mode execution it in standalone mode:

mvn clean instal 
java -jar target/consistent-hash-exchange-policy-engine-0.0.1-SNAPSHOT.jar 

Containerized mode:

In containerized mode there is an extra prerequisites. This consist in enabling a load balancer in front of the workers. Traefik load balancer is selected for that. You can access traefik at http://localhost:8080/dashboard/

Start Traefik load balancer

sudo service apache2 stop //Stop apache because traefik uses the port 80
docker-compose up -d reverse-proxy 

Create policyengine container(s)

docker  build -t consistentpolicyengine . // build policy engine image
docker-compose up -d consistentpolicyengine // Create only one worker
docker-compose up -d --scale consistentpolicyengine=2  //Create a cluster of policy engine containers

Some usefull commmands for testing are:

docker image prune -a // remove all images which are not used by existing containers  
docker rm $(docker stop $(docker ps -a -q --filter ancestor=consistentpolicyengine --format="{{.ID}}")) // kill all policy engine workers
docker logs consistent-hash-exchange-policy-engine_consistentpolicyengine_1 --follow //read logs from a worker
docker exec -it  consistent-hash-exchange-policy-engine_consistentpolicyengine_1  bash // get inside the container

References:

https://arxiv.org/pdf/1406.2294.pdf
https://stattrek.com/chi-square-test/independence.aspx
https://www.uuidgenerator.net/

Useful and brief explication of how consistent hash function works

License

This component is published under Apache 2.0 license. Please see the LICENSE file for more details.

Lead Developers

The following lead developers are responsible for this repository and have admin rights. They can, for example, merge pull requests.

• Eleni Fotopoulou (@elfo)
• Anastasios Zafeiropoulos (@tzafeir )