The java metric agent is a metric-gathering extension for a web application. It gathers metrics about requests and responses served by the application.

• Uniquely identify every Http Request/Response pair by Response Header 'X-Metric-Trace-Id'.
• Embedded http server to display gathered metrics on the fly and to look up historical request time/response size by the unique identifier.
• Support Request Time Metric to measure time spent between when the application starts to process the request, and the time when the application sends the response to the client.
• Support Response Sizes to measure the size of the HTTP response body in bytes.

1. Build the agent jar, see section Building.
2. Copy jar file on the path: /agent/build/libs/agent-all.jar
3. To install the Java agent you need to configure your JVM to load the agent by passing the -javaagent:/full/path/to/agent-all.jar command-line argument.

The Java agent requires JDK 1.8.0_265 to build; your JAVA_HOME must be set to this JDK version.

To build the agent jar, run the following command from the project root directory:
./gradlew clean agent:shadowJar

To build and run all checks:
./gradlew clean build

After building, Java agent artifacts folder:

• Agent: agent/build/shadowJar/agent.jar

To run unit tests: ./gradlew test

To run integration tests: ./gradlew integrationTest

To run the application: ./gradlew bootRun

Open in Chrome with dev tools: http:\\localhost:3030\

Each response has header 'X-Metric-Trace-Id' with UUID to fetch request/response metrics on page: http:\\localhost:8081\

• requestOperationTime is Request Time Metric to measure time spent between when the application starts to process the request, and the time when the application sends the response to the client;
• responseBodyLength is Response Size Metric to measure the size of the HTTP response body in bytes.

• support Java 8+ runtimes;
• make configurable agent initialization. I.e. embedded server port, etc;
• provide the agent api jar to record custom metrics in user application;
• add more build-in metrics. I.e. JVM GC, servlet containers stats.

MIT