Chapter 10. Observability in JBoss EAP

Procedure

1. In the CLI, use the mvn command to set up a Maven project. This command creates the directory structure for the project and the pom.xml configuration file.

   Syntax

   $ mvn archetype:generate \
   -DgroupId=<group-to-which-your-application-belongs> \
   -DartifactId=<name-of-your-application> \
   -DarchetypeGroupId=org.apache.maven.archetypes \
   -DarchetypeArtifactId=maven-archetype-webapp \
   -DinteractiveMode=false

   Example

   $ mvn archetype:generate \
   -DgroupId=com.example.opentelemetry \
   -DartifactId=simple-tracing-example \
   -DarchetypeGroupId=org.apache.maven.archetypes \
   -DarchetypeArtifactId=maven-archetype-webapp \
   -DinteractiveMode=false

2. Navigate to the application root directory.

   Syntax

   $ cd <name-of-your-application>

   Example

   $ cd simple-tracing-example

3. Update the generated pom.xml file.

   1. Set the following properties:

      <properties>
          <maven.compiler.source>1.8</maven.compiler.source>
          <maven.compiler.target>1.8</maven.compiler.target>
          <failOnMissingWebXml>false</failOnMissingWebXml>
          <version.server.bom>4.0.0.GA</version.server.bom>
          <version.wildfly-jar.maven.plugin>6.1.1.Final</version.wildfly-jar.maven.plugin>
      </properties>

   2. Set the following dependencies:

      <dependencies>
          <dependency>
              <groupId>jakarta.enterprise</groupId>
              <artifactId>jakarta.enterprise.cdi-api</artifactId>
              <version>2.0.2</version>
              <scope>provided</scope>
          </dependency>
      
          <dependency>
              <groupId>org.jboss.spec.javax.ws.rs</groupId>
              <artifactId>jboss-jaxrs-api_2.1_spec</artifactId>
              <version>2.0.2.Final</version>
              <scope>provided</scope>
          </dependency>
      
          <dependency>
              <groupId>io.opentelemetry</groupId>
              <artifactId>opentelemetry-api</artifactId>
              <version>1.5.0</version>
              <scope>provided</scope>
          </dependency>
      </dependencies>

   3. Set the following build configuration to use mvn widlfy:deploy to deploy the application:

      <build>
        <!-- Set the name of the archive -->
        <finalName>${project.artifactId}</finalName>
        <plugins>
          <!-- Allows to use mvn wildfly:deploy -->
          <plugin>
            <groupId>org.wildfly.plugins</groupId>
            <artifactId>wildfly-maven-plugin</artifactId>
          </plugin>
        </plugins>
      </build>

Procedure

1. In the <application_root>, create a directory to store the Java files.

   Syntax

   $ mkdir -p src/main/java/com/example/opentelemetry

   Example

   $ mkdir -p src/main/java/com/example/opentelemetry

2. Navigate to the new directory.

   Syntax

   $ cd src/main/java/com/example/opentelemetry

   Example

   $ cd src/main/java/com/example/opentelemetry

3. Create a JakartaRestApplication.java file with the following content. This JakartaRestApplication class declares the application as a Jakarta RESTful Web Services application.

   package com.example.opentelemetry;
   
   import javax.ws.rs.ApplicationPath;
   import javax.ws.rs.core.Application;
   
   @ApplicationPath("/")
   public class JakartaRestApplication extends Application {
   }

4. Create an ExplicitlyTracedBean.java file with the following content for the class ExplicitlyTracedBean. This class creates custom spans by injecting a Tracer class.

   package com.example.opentelemetry;
   
   import javax.enterprise.context.RequestScoped;
   import javax.inject.Inject;
   import io.opentelemetry.api.trace.Span;
   import io.opentelemetry.api.trace.Tracer;
   
   @RequestScoped
   public class ExplicitlyTracedBean {
   
       @Inject
       private Tracer tracer; 

   1

   
   
       public String getHello() {
           Span prepareHelloSpan = tracer.spanBuilder("prepare-hello").startSpan(); 

   2

   
           prepareHelloSpan.makeCurrent();
   
           String hello = "hello";
   
           Span processHelloSpan = tracer.spanBuilder("process-hello").startSpan(); 

   3

   
           processHelloSpan.makeCurrent();
   
           hello = hello.toUpperCase();
   
           processHelloSpan.end();
           prepareHelloSpan.end();
   
           return hello;
       }
   }

   1

   Inject a Tracer class to create custom spans.

   2

   Create a span called prepare-hello to indicate that the method getHello() was called.

   3

   Create a span called process-hello to indicate that the value hello was assigned to a new String object called hello.

5. Create a TracedResource.java file with the following content for TracedResource class. This file injects the ExplicitlyTracedBean class and declares two endpoints: traced and cdi-trace.

   package com.example.opentelemetry;
   
   import javax.enterprise.context.RequestScoped;
   import javax.inject.Inject;
   import javax.ws.rs.GET;
   import javax.ws.rs.Path;
   import javax.ws.rs.Produces;
   import javax.ws.rs.core.MediaType;
   
   @Path("/hello")
   @RequestScoped
   public class TracedResource {
       @Inject
       private ExplicitlyTracedBean tracedBean;
   
       @GET
       @Path("/traced")
       @Produces(MediaType.TEXT_PLAIN)
       public String hello() {
           return "hello";
       }
   
       @GET
       @Path("/cdi-trace")
       @Produces(MediaType.TEXT_PLAIN)
       public String cdiHello() {
           return tracedBean.getHello();
       }
   }

6. Navigate to the application root directory.

   Syntax

   $ cd <path_to_application_root>/<application_root>

   Example

   $ cd ~/applications/simple-tracing-example

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

   $ mvn clean package wildfly:deploy

8. Start the Jaeger console.

   $ docker run -d --name jaeger \
     -e COLLECTOR_ZIPKIN_HOST_PORT=:9411 \
     -p 5775:5775/udp \
     -p 6831:6831/udp \
     -p 6832:6832/udp \
     -p 5778:5778 \
     -p 16686:16686 \
     -p 14268:14268 \
     -p 14250:14250 \
     -p 9411:9411 \
     jaegertracing/all-in-one:1.29

9. In a browser, navigate to \localhost:8080/simple-tracing-example/hello/cdi-trace.
10. In a browser, open the Jaeger console at http://localhost:16686/search.
11. In the Jaeger console, select JBoss EAP XP and click Find Traces.
12. Click 3 Spans.

13. The Jaeger console displays the following traces:

    |GET /hello/cdi-trace 

    1

    
    -
     | prepare-hello 

    2

    
      -
       | process-hello 

    3

    1

    This is the span for the automatic implicit trace.

    2

    The custom span prepare-hello indicates that the method getHello() was called. It is the child of span for the automatic implicit trace.

    3

    The custom span process-hello indicates that the value hello was assigned to a new String object hello. It is the child of the prepare-hello span.