The looper microservice runs a dozen calls to portfolio REST APIs in a loop. You can use this for performance and load testing. It calls the portfolio service via the mpRestClient from MicroProfile, and builds and passes the JWT that it requires.

Note it deliberately does not cause any changes in loyalty level, since Twitter will disable your account if you blast in too many tweets per second. It also doesn't talk to Watson, since you only get 2500 free calls per month before it starts charging you per call.

It responds to a GET ?count={count} REST request, where you pass in the count of how many iterations to run. If you omit the count query param, it assumes 1 iteration.

For example, if you hit the http://localhost:9080/looper?count=5 URL, it would run 5 iterations. It returns the output from the various calls (various collections of JSON) as text/plain.

Note that the call doesn't return until all the iterations are complete. So you might be waiting a long time in a browser (or curl) if you request a high count. To address that, there's also a command-line client that will also get installed to the pod running the looper servlet. Just kubectl exec into the pod, and then run loopctl.sh, passing it parameters as explained when you run it with no parameters. It will run a specified number of iterations, on a specified number of parallel threads. You will see output from every iteration, with timings. Or you can build the CLI client locally and run it from your laptop, passing the node port or ingress URL of where the looper servlet is running.

Deploy

Use WebSphere Liberty helm chart to deploy Looper microservice:

helm repo add ibm-charts https://raw.githubusercontent.com/IBM/charts/master/repo/stable/
helm install ibm-charts/ibm-websphere-liberty -f <VALUES_YAML> -n <RELEASE_NAME> --tls

In practice this means you'll run something like:

helm repo add ibm-charts https://raw.githubusercontent.com/IBM/charts/master/repo/stable/
helm install ibm-charts/ibm-websphere-liberty -f manifests/looper-values.yaml -n looper --namespace stock-trader --tls