Business-related metrics that are emitted from our application might contain parameters (i.e. tags or labels) for which a specific metric is being measured. Since MicroProfile Metrics 2.0 it’s possible to assign tags to specific metrics using the API.
Declarative approach
Assuming we have the following resource:
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 | @Path("greetings")public class GreetingsResource { @GET @Path("hello") @Counted(name = "greetings", tags = "greeting=formal") public String hello() { return "Здравствуйте"; } @GET @Path("hi") @Counted(name = "greetings", tags = "greeting=casual") public String hi() { return "Привет"; }} |
Depending on which resource will be accessed, we’ll increment the counter that is identified by the name greetings and one of the tags greeting=formal or greeting=casual:
When we access the MicroProfile Metrics endpoint, we’ll see our metrics’ values:
1 2 3 4 5 6 | curl http://localhost:9080/metrics/[...]# TYPE application_com_example_GreetingsResource_greetings_total counterapplication_com_example_GreetingsResource_greetings_total{greeting="formal"} 2# TYPE application_com_example_GreetingsResource_greetings_total counterapplication_com_example_GreetingsResource_greetings_total{greeting="casual"} 5 |
Programmatic approach
It’s also possible to dynamically create and retrieve metrics depending on the values of their tags.
For business logic that creates cars, we can dynamically create or retrieve a counter as follows:
01 02 03 04 05 06 07 08 09 10 11 12 13 | public class CarManufacturer { @Inject MetricRegistry metricRegistry; public void createCar(CarColor color) { Counter counter = metricRegistry.counter("cars_produced", new Tag("color", color.name())); counter.inc(); // ... }} |
Resulting in similar, tagged metrics:
1 2 3 4 5 6 | curl http://localhost:9080/metrics/[...]# TYPE application_cars_produced_total counterapplication_cars_produced_total{color="blue"} 1# TYPE application_cars_produced_total counterapplication_cars_produced_total{color="red"} 3 |
You can already try out this and other MicroProfile 3.0 features on Open Liberty version 19.0.0.7.
This change in the Metrics API makes using other, third-party libraries obsolete. This usage can now be replaced with MicroProfile Metrics 2.0.
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Published on Java Code Geeks with permission by Sebastian Daschner, partner at our JCG program. See the original article here: Using metric tags with MicroProfile Metrics 2.0 Opinions expressed by Java Code Geeks contributors are their own. |
