If you create a Grails 3 app and run it; it will start at port 8080.
$ grails --version Picked up JAVA_TOOL_OPTIONS: -Dfile.encoding=UTF-8 -Duser.language=en -Duser.region=US | Grails Version: 3.0.14 | Groovy Version: 2.4.5 | JVM Version: 1.8.0_45 $ grails create-app testnewport | Application created at /Users/groovycalamari/Documents/tests/testnewport $ cd testnewport $ grails run-app Grails application running at http://localhost:8080 in environment: development
If you want to start it at a different port add to your application.yml the next block:
--- server: port: 28080
Grails application running at http://localhost:28080 in environment: development
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