The Fuse circuit breaker booster consists of two related services:

• A name service, which returns a name to greet, and

• A greetings service, which invokes the name service to get a name and then returns the string, Hello, NAME.

In this demonstration, the Hystrix circuit breaker is inserted between the greetings service and the name service. If the name service becomes unavailable, the greetings service can fall back to an alternative behaviour and respond to the client immediately, instead of blocking while it waits for the name service to restart.

This booster can run in the following modes:

• Standalone on your machine

• Single-node OpenShift cluster

• OpenShift Online at https://developers.redhat.com/launch

The most effective way to demonstrate the circuit breaker is to deploy and run the project on OpenShift. For more details about running this booster on a single-node OpenShift cluster, CI/CD deployments, as well as the rest of the runtime, see the Spring Boot Runtime Guide.

You can run this booster as a standalone project on your local machine:

1. Download the project and extract the archive on your local filesystem.

2. Build the project:

   $ cd PROJECT_DIR
   $ mvn clean package

3. In two separate shell prompts, run the services as follows:

   $ cd name-service
   $ mvn spring-boot:run -Dserver.port=8081

   and

   $ cd greetings-service
   $ mvn spring-boot:run

4. Visit http://localhost:8080 and follow the instructions on that page.

If you have a single-node OpenShift cluster, such as Minishift or the Red Hat Container Development Kit, installed and running, you can deploy your booster there. A single-node OpenShift cluster provides you with access to a cloud environment that is similar to a production environment.

To deploy your booster to a running single-node OpenShift cluster:

1. Download the project and extract the archive on your local filesystem.

2. Log in to your OpenShift cluster:

   $ oc login -u developer -p developer

3. Create a new OpenShift project for the booster:

   $ oc new-project MY_PROJECT_NAME

4. Build and deploy the project to the OpenShift cluster:

   $ mvn clean -DskipTests fabric8:deploy -Popenshift

5. In your browser, navigate to the MY_PROJECT_NAME project in the OpenShift console. Wait until you can see that the pods for the name-service application and for the greetings-service application have both started up.

6. Just above the entry for the greetings-service application on the Overview page, there is a URL of the form http://greetings-service-MY_PROJECT_NAME.OPENSHIFT_IP_ADDR.nip.io. Click on the URL to access the greetings service application and follow the instructions on that page.

You can deploy the circuit breaker booster directly to OpenShift Online when you create the project at https://developers.redhat.com/launch.

1. Visit https://developers.redhat.com/launch.

2. At the Deployment step, select Use OpenShift Online.

3. Follow the on-screen instructions to create a new Circuit Breaker project using the Fuse runtime.