tweak OpenTelemetry configuration

Author: jkt-signal

service/src/main/java/org/whispersystems/textsecuregcm/configuration/OpenTelemetryConfiguration.java

@@ -8,13 +8,17 @@
 import com.fasterxml.jackson.annotation.JsonAnyGetter;
 import com.fasterxml.jackson.annotation.JsonAnySetter;
 import com.fasterxml.jackson.annotation.JsonProperty;
+
+import io.micrometer.registry.otlp.HistogramFlavor;
 import io.micrometer.registry.otlp.OtlpConfig;
 import java.time.Duration;
 import java.util.Map;
 
 public record OpenTelemetryConfiguration(
   @JsonProperty boolean enabled,
   @JsonProperty Duration shutdownWaitDuration,
+  @JsonProperty int maxBucketCount,
+  @JsonProperty Map<String, Integer> maxBucketsPerMeter,
   @JsonAnyGetter @JsonAnySetter Map<String, String> otlpConfig
 ) implements OtlpConfig {
 
@@ -23,6 +27,19 @@ public String get(String key) {
     return otlpConfig.get(key.split("\\.", 2)[1]);
   }
 
+  @Override
+  public Map<String, Integer> maxBucketsPerMeter() {
+    if (maxBucketsPerMeter == null) {
+      return Map.of();
+    }
+    return maxBucketsPerMeter;
+  }
+
+  @Override
+  public HistogramFlavor histogramFlavor() {
+    return HistogramFlavor.BASE2_EXPONENTIAL_BUCKET_HISTOGRAM;
+  }
+
   public Duration shutdownWaitDuration() {
     if (shutdownWaitDuration == null) {
       return step().plus(step().dividedBy(2));

service/src/main/java/org/whispersystems/textsecuregcm/metrics/MetricsUtil.java

@@ -65,7 +65,7 @@ public static void configureRegistries(final WhisperServerConfiguration config,
 
     Duration shutdownWaitDuration = Duration.ZERO;
 
-    if (config.getDatadogConfiguration() != null && config.getDatadogConfiguration().enabled()) {
+    if (config.getDatadogConfiguration().enabled()) {
       final StatsdMeterRegistry dogstatsdMeterRegistry = new StatsdMeterRegistry(
           config.getDatadogConfiguration(), io.micrometer.core.instrument.Clock.SYSTEM);
 
@@ -81,7 +81,7 @@ public static void configureRegistries(final WhisperServerConfiguration config,
       shutdownWaitDuration = config.getDatadogConfiguration().getShutdownWaitDuration();
     }
 
-    if (config.getOpenTelemetryConfiguration() != null && config.getOpenTelemetryConfiguration().enabled()) {
+    if (config.getOpenTelemetryConfiguration().enabled()) {
       final OtlpMeterRegistry otlpMeterRegistry = new OtlpMeterRegistry(
         config.getOpenTelemetryConfiguration(), io.micrometer.core.instrument.Clock.SYSTEM);