Chapter 7. Develop Micrometer application for JBoss EAP

Procedure

1. Open a terminal.

2. Start JBoss EAP as a standalone server by using the following script:

   $ <EAP_HOME>/bin/standalone.sh -c standalone-microprofile.xml

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   Note

   For Windows server, use the <EAP_HOME>\bin\standalone.bat script.

3. Open a new terminal.
4. Navigate to the application root directory.

5. Run the following command to configure the server:

   $ <EAP_HOME>/bin/jboss-cli.sh --connect --file=configure-micrometer.cli

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   Note

   For Windows server, use the <EAP_HOME>\bin\jboss-cli.bat script.

   Replace <EAP_HOME> with the path to your server.

   Expected output:

   The batch executed successfully
   process-state: reload-required

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6. Reload the server with the following management command:

   $ <EAP_HOME>/bin/jboss-cli.sh --connect --commands=reload

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7. Create a configuration file named docker-compose.yaml with the following content:

   version: "3"
   
   services:
     otel-collector:
       image: otel/opentelemetry-collector
       command: [--config=/etc/otel-collector-config.yaml]
       volumes:
         - ./otel-collector-config.yaml:/etc/otel-collector-config.yaml:Z
       ports:
         - 1888:1888 # pprof extension
         - 8888:8888 # Prometheus metrics exposed by the collector
         - 8889:8889 # Prometheus exporter metrics
         - 13133:13133 # health_check extension
         - 4317:4317 # OTLP gRPC receiver
         - 4318:4318 # OTLP http receiver
         - 55679:55679 # zpages extension
         - 1234:1234 # /metrics endpoint

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8. Create a configuration file named otel-collector-config.yaml with the following content:

   extensions:
     health_check:
     pprof:
       endpoint: 0.0.0.0:1777
     zpages:
       endpoint: 0.0.0.0:55679
   
   receivers:
     otlp:
       protocols:
         grpc:
         http:
   
   processors:
     batch:
   
   exporters:
     prometheus:
       endpoint: "0.0.0.0:1234"
   
   service:
     pipelines:
       metrics:
         receivers: [otlp]
         processors: [batch]
         exporters: [prometheus]
   
     extensions: [health_check, pprof, zpages]

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9. Start the collector server instance by running the following command:

   $ docker-compose up

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   Note

   You can also use Podman instead of Docker. If you choose Podman, then use the $ podman-compose up command instead of $ docker-compose up. If Docker or Podman is not supported in your environment, then see Otel Collector documentation for guidance on installing and running the OpenTelemetry Collector.

10. In the RootResource class, see how the MeterRegistry is injected into your class to ensure proper setup before registering the meters.

    @Path("/")
    @ApplicationScoped
    public class RootResource {
        // ...
        @Inject
        private MeterRegistry registry;
    
        private Counter performCheckCounter;
        private Counter originalCounter;
        private Counter duplicatedCounter;
    
        @PostConstruct
        private void createMeters() {
            Gauge.builder("prime.highestSoFar", () -> highestPrimeNumberSoFar)
                    .description("Highest prime number so far.")
                    .register(registry);
            performCheckCounter = Counter
                    .builder("prime.performedChecks")
                    .description("How many prime checks have been performed.")
                    .register(registry);
            originalCounter = Counter
                    .builder("prime.duplicatedCounter")
                    .tags(List.of(Tag.of("type", "original")))
                    .register(registry);
            duplicatedCounter = Counter
                    .builder("prime.duplicatedCounter")
                    .tags(List.of(Tag.of("type", "copy")))
                    .register(registry);
        }
        // ...
    }

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11. Inspect the checkIfPrime() method body to see how to use the registered meters within your application logic. For example:

    @GET
    @Path("/prime/{number}")
    public String checkIfPrime(@PathParam("number") long number) throws Exception {
        performCheckCounter.increment();
    
        Timer timer = registry.timer("prime.timer");
    
        return timer.recordCallable(() -> {
    
            if (number < 1) {
                return "Only natural numbers can be prime numbers.";
            }
    
            if (number == 1) {
                return "1 is not prime.";
            }
    
            if (number == 2) {
                return "2 is prime.";
            }
    
            if (number % 2 == 0) {
                return number + " is not prime, it is divisible by 2.";
            }
    
            for (int i = 3; i < Math.floor(Math.sqrt(number)) + 1; i = i + 2) {
                try {
                    Thread.sleep(10);
                } catch (InterruptedException e) {
                    //
                }
                if (number % i == 0) {
                    return number + " is not prime, is divisible by " + i + ".";
                }
            }
    
            if (number > highestPrimeNumberSoFar) {
                highestPrimeNumberSoFar = number;
            }
    
            return number + " is prime.";
        });
    }

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12. Navigate to the application root directory.

    Syntax

    $ cd <path_to_application_root>/<application_root>

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    Example, in reference to the Micrometer Quickstart:

    $ cd ~/quickstarts/micrometer

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13. Compile and deploy the application with the following command:

    $ mvn clean package wildfly:deploy

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Verification

1. Access the application by using a web browser or you can run the following command.

   $ curl http://localhost:8080/micrometer/prime/13

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   Expected output:

   13 is prime.

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