Sorry, this repository is not being maintained, latest version of Gatling has support for feeders (to feed input json), do checkout Gatling's website.
Step 1 : Change to directory to micro-services/ecommerce-microservices/user-microservice
Step 2 : Run $ mvn package
Step 3 : The above will create a JAR in the target directory
Building jar: target/user-microservice-0.0.1-SNAPSHOT.jar
$ java -jar target/user-microservice-0.0.1-SNAPSHOT.jar
Step 1 : Open the URL from a browser - http://localhost:9001/users
Step 1 : Open another command prompt
Step 2 : Change to directory micro-services/tests/user-microservice-gatling-tests
Step 3 : mvn clean gatling:execute
courtesy @adhulappanavar