add jmx exporter to container image

.github/Dockerfile_PreBuild

@@ -1,5 +1,10 @@
 FROM jetty:9.4-jdk11-alpine
 
+ENV JMX_EXPORTER_VERSION=1.2.0
+
+# To enable add "-javaagent:$JETTY_BASE/jmx-exporter.jar=8090:$JETTY_BASE/prometheus_config.yml" to the JAVA_OPTIONS
+RUN wget https://repo1.maven.org/maven2/io/prometheus/jmx/jmx_prometheus_javaagent/$JMX_EXPORTER_VERSION/jmx_prometheus_javaagent-$JMX_EXPORTER_VERSION.jar -o /var/lib/jetty/jmx-exporter.jar
+COPY .github/jmx_exporter.config /var/lib/jetty/prometheus_config.yml
 # Copy OBP source code
 # Copy build artifact (.war file) into jetty from 'maven' stage.
 COPY /obp-api/target/obp-api-1.*.war /var/lib/jetty/webapps/ROOT.war

.github/jmx_exporter.config

@@ -0,0 +1,15 @@
+---
+lowercaseOutputLabelNames: true
+lowercaseOutputName: true
+whitelistObjectNames: ["java.lang:type=OperatingSystem"]
+blacklistObjectNames: []
+rules:
+- pattern: 'java.lang<type=OperatingSystem><>(committed_virtual_memory|free_physical_memory|free_swap_space|total_physical_memory|total_swap_space)_size:'
+  name: os_$1_bytes
+  type: GAUGE
+  attrNameSnakeCase: true
+- pattern: 'java.lang<type=OperatingSystem><>((?!process_cpu_time)\w+):'
+  name: os_$1
+  type: GAUGE
+  attrNameSnakeCase: true
+- pattern: ".*"