Working with a customer last week we determined that Spring Boot applications using Liberty Buildpack failed to allow the "Auto-Scale" service to show up "Throughput" metrics and essentially mean we couldn't scale out or down application instances using Throughput metrics.
It turns out the Agent within the IBM Liberty buildpack isn't quite picking up application WAR files created using Spring Boot and hence "Monitoring and Analytics" and "Auto-Scale" service have limited functionality.
IBM Bluemix Services
To solve this we simply need to select the correct generated WAR file. Spring Boot along with Maven produces two WAR files as shown below when the application packaged as a WAR is packaged using "mvn package"
-rw-r--r-- 1 pasapicella staff 12341953 13 May 14:17 demo-sb-war-0.0.1-SNAPSHOT.war.original
-rw-r--r-- 1 pasapicella staff 17229369 13 May 14:17 demo-sb-war-0.0.1-SNAPSHOT.war
The WAR file "demo-sb-war-0.0.1-SNAPSHOT.war.original" is the one that is originally generated using maven and it's this file which we should push to IBM Bluemix using the IBM Liberty buildpack
If there’s a Main-Class defined in the manifest it attempts to start it up using the war file, thats the WAR file "demo-sb-war-0.0.1-SNAPSHOT.war". Once you push the version of our war without the Main-Class Manifest entry defined "demo-sb-war-0.0.1-SNAPSHOT.war.original" everything starts up correctly and is now happily recording both throughput and monitoring. If the WAR has a Main-Class app, the buildpack will only install the JDK for the app, and the app embeds Tomcat (by default for Spring Boot), so essentially the app is running on Tomcat; if it's a WAR app without Main-Class manifest entry, the buildpack installs Liberty as well and the app will run on Liberty.
Simply push the correct WAR file and your Spring Boot WAR files using Liberty Buildpack can take advantage of the Liberty Buildpack agent for extra "Monitoring" and "Auto-Scale" service support.
Screen Shots for Monitoring and Analytics service with Spring Boot WAR file
To verify this you can use the Basic Spring Boot Application at the following URL. It simply exposes one REST end point service displaying "helloworld".