Remove micrometer dependency and replace with OpenTelemetry metrics

Co-authored-by: trask <218610+trask@users.noreply.github.com>

Author: Copilot

reference-application/build.gradle.kts

@@ -22,9 +22,6 @@ dependencies {
     implementation("org.springframework.boot:spring-boot-starter-web")
     implementation("org.springframework.boot:spring-boot-starter-actuator")
 
-    // Micrometer for additional metrics
-    implementation("io.micrometer:micrometer-registry-prometheus")
-    
     // Java agent
     agent("io.opentelemetry.javaagent:opentelemetry-javaagent:2.20.1")
 

reference-application/src/main/java/io/opentelemetry/example/FibonacciController.java

@@ -1,9 +1,9 @@
 package io.opentelemetry.example;
 
-import io.micrometer.core.instrument.Counter;
-import io.micrometer.core.instrument.Timer;
 import io.opentelemetry.api.OpenTelemetry;
 import io.opentelemetry.api.common.Attributes;
+import io.opentelemetry.api.metrics.LongCounter;
+import io.opentelemetry.api.metrics.Meter;
 import io.opentelemetry.api.trace.Span;
 import io.opentelemetry.api.trace.SpanKind;
 import io.opentelemetry.api.trace.StatusCode;
@@ -23,19 +23,22 @@
 public class FibonacciController {
   private static final Logger logger = LoggerFactory.getLogger(FibonacciController.class);
 
-  @Autowired private Counter fibonacciCounter;
-
-  @Autowired private Timer fibonacciTimer;
-
   private final Tracer tracer;
+  private final LongCounter fibonacciCounter;
 
   public FibonacciController(@Autowired OpenTelemetry openTelemetry) {
     this.tracer = openTelemetry.getTracer("dice-server", "1.0.0");
+    Meter meter = openTelemetry.getMeter("dice-server");
+    this.fibonacciCounter =
+        meter
+            .counterBuilder("fibonacci_calculations_total")
+            .setDescription("Total number of fibonacci calculations")
+            .build();
   }
 
   @GetMapping("/fibonacci")
   public Map<String, Object> fibonacci(@RequestParam("n") int n) {
-    Timer.Sample sample = Timer.start();
+    long startTime = System.nanoTime();
 
     Span span =
         tracer
@@ -55,26 +58,28 @@ public Map<String, Object> fibonacci(@RequestParam("n") int n) {
 
       logger.info("Calculating fibonacci for n={}", n);
 
-      long startTime = System.nanoTime();
+      long computationStartTime = System.nanoTime();
       BigInteger result = calculateFibonacci(n);
-      long duration = System.nanoTime() - startTime;
+      long computationDuration = System.nanoTime() - computationStartTime;
 
-      fibonacciCounter.increment();
-      sample.stop(fibonacciTimer);
+      fibonacciCounter.add(1);
+      long totalDuration = System.nanoTime() - startTime;
 
       span.addEvent(
           "fibonacci-calculated",
           Attributes.builder()
               .put("fibonacci.result_length", result.toString().length())
-              .put("fibonacci.duration_ns", duration)
+              .put("fibonacci.computation_duration_ns", computationDuration)
+              .put("fibonacci.total_duration_ns", totalDuration)
               .build());
 
-      logger.info("Fibonacci({}) = {} (computed in {}ms)", n, result, duration / 1_000_000);
+      logger.info(
+          "Fibonacci({}) = {} (computed in {}ms)", n, result, computationDuration / 1_000_000);
 
       Map<String, Object> response = new HashMap<>();
       response.put("n", n);
       response.put("result", result.toString());
-      response.put("duration_ms", duration / 1_000_000);
+      response.put("duration_ms", computationDuration / 1_000_000);
 
       return response;
     } catch (Exception e) {

reference-application/src/main/java/io/opentelemetry/example/ReferenceApplication.java

@@ -1,8 +1,5 @@
 package io.opentelemetry.example;
 
-import io.micrometer.core.instrument.Counter;
-import io.micrometer.core.instrument.MeterRegistry;
-import io.micrometer.core.instrument.Timer;
 import io.opentelemetry.api.GlobalOpenTelemetry;
 import io.opentelemetry.api.OpenTelemetry;
 import org.springframework.boot.SpringApplication;
@@ -20,32 +17,4 @@ public static void main(String[] args) {
   public OpenTelemetry openTelemetry() {
     return GlobalOpenTelemetry.get();
   }
-
-  @Bean
-  public Counter diceRollCounter(MeterRegistry meterRegistry) {
-    return Counter.builder("dice_rolls_total")
-        .description("Total number of dice rolls")
-        .register(meterRegistry);
-  }
-
-  @Bean
-  public Timer diceRollTimer(MeterRegistry meterRegistry) {
-    return Timer.builder("dice_roll_duration")
-        .description("Time taken to roll dice")
-        .register(meterRegistry);
-  }
-
-  @Bean
-  public Counter fibonacciCounter(MeterRegistry meterRegistry) {
-    return Counter.builder("fibonacci_calculations_total")
-        .description("Total number of fibonacci calculations")
-        .register(meterRegistry);
-  }
-
-  @Bean
-  public Timer fibonacciTimer(MeterRegistry meterRegistry) {
-    return Timer.builder("fibonacci_duration")
-        .description("Time taken to calculate fibonacci")
-        .register(meterRegistry);
-  }
 }

reference-application/src/main/java/io/opentelemetry/example/RollController.java

@@ -1,11 +1,11 @@
 package io.opentelemetry.example;
 
-import io.micrometer.core.instrument.Counter;
-import io.micrometer.core.instrument.Timer;
 import io.opentelemetry.api.OpenTelemetry;
 import io.opentelemetry.api.baggage.Baggage;
 import io.opentelemetry.api.baggage.BaggageBuilder;
 import io.opentelemetry.api.common.Attributes;
+import io.opentelemetry.api.metrics.LongCounter;
+import io.opentelemetry.api.metrics.Meter;
 import io.opentelemetry.api.trace.Span;
 import io.opentelemetry.api.trace.SpanKind;
 import io.opentelemetry.api.trace.StatusCode;
@@ -28,22 +28,25 @@ public class RollController {
 
   @Autowired private OpenTelemetry openTelemetry;
 
-  @Autowired private Counter diceRollCounter;
-
-  @Autowired private Timer diceRollTimer;
-
   private final Tracer tracer;
+  private final LongCounter diceRollCounter;
 
   public RollController(@Autowired OpenTelemetry openTelemetry) {
     this.tracer = openTelemetry.getTracer("dice-server", "1.0.0");
+    Meter meter = openTelemetry.getMeter("dice-server");
+    this.diceRollCounter =
+        meter
+            .counterBuilder("dice_rolls_total")
+            .setDescription("Total number of dice rolls")
+            .build();
   }
 
   @GetMapping("/rolldice")
   public Map<String, Object> rollDice(
       @RequestParam("player") Optional<String> player,
       @RequestParam("rolls") Optional<Integer> rolls) {
 
-    Timer.Sample sample = Timer.start();
+    long startTime = System.nanoTime();
 
     Span span =
         tracer
@@ -72,8 +75,9 @@ public Map<String, Object> rollDice(
           results[i] = rollSingleDie();
         }
 
-        diceRollCounter.increment();
-        sample.stop(diceRollTimer);
+        // Record metrics using OpenTelemetry
+        diceRollCounter.add(1);
+        long duration = System.nanoTime() - startTime;
 
         String playerName = player.orElse("Anonymous player");
         if (numRolls == 1) {
@@ -91,6 +95,7 @@ public Map<String, Object> rollDice(
             Attributes.builder()
                 .put("dice.result", java.util.Arrays.toString(results))
                 .put("dice.sum", java.util.Arrays.stream(results).sum())
+                .put("dice.duration_ms", duration / 1_000_000)
                 .build());
 
         Map<String, Object> response = new HashMap<>();

reference-application/src/main/resources/application.yml

@@ -10,18 +10,12 @@ management:
   endpoints:
     web:
       exposure:
-        include: health,info,metrics,prometheus
+        include: health,info,metrics
   endpoint:
     health:
       show-details: always
     metrics:
       enabled: true
-    prometheus:
-      enabled: true
-  metrics:
-    export:
-      prometheus:
-        enabled: true
 
 # Logging configuration
 logging: