Hacky bridge to grab dropwizard metrics and stick them into a micrometer registry. Add as a spring-boot Bean

DropwizardToMicrometerBridge.java

package com.boohoo.esbdefused.metrics;

import java.util.Arrays;
import java.util.concurrent.TimeUnit;

import com.codahale.metrics.Counter;
import com.codahale.metrics.Gauge;
import com.codahale.metrics.Histogram;
import com.codahale.metrics.Meter;
import com.codahale.metrics.MetricRegistry;
import com.codahale.metrics.MetricRegistryListener;
import com.codahale.metrics.Sampling;
import com.codahale.metrics.Timer;

import io.micrometer.core.instrument.MeterRegistry;
import io.micrometer.core.instrument.Tags;

public class DropwizardToMicrometerBridge implements MetricRegistryListener {

	private final MeterRegistry meterRegistry;

	public DropwizardToMicrometerBridge(MeterRegistry meterRegistry, MetricRegistry metricRegistry) {
		this.meterRegistry = meterRegistry;
		metricRegistry.addListener(this);
	}

	@Override
	public void onGaugeAdded(String name, Gauge<?> gauge) {
		meterRegistry.gauge(name, gauge, DropwizardToMicrometerBridge::doubleValue);
	}

	@Override
	public void onGaugeRemoved(String name) {
		throw new RuntimeException("Method not implemented");
	}

	@Override
	public void onCounterAdded(String name, Counter counter) {
		meterRegistry.more().counter(name, Tags.empty(), counter, Counter::getCount);
	}

	@Override
	public void onCounterRemoved(String name) {
		throw new RuntimeException("Method not implemented");
	}

	@Override
	public void onHistogramAdded(String name, Histogram histogram) {
		meterRegistry.more().timer(name, Tags.empty(), histogram, Histogram::getCount, DropwizardToMicrometerBridge::totalTime, TimeUnit.MILLISECONDS);
	}

	@Override
	public void onHistogramRemoved(String name) {
		throw new RuntimeException("Method not implemented");
	}

	@Override
	public void onMeterAdded(String name, Meter meter) {
		meterRegistry.more().counter(name, Tags.empty(), meter, Meter::getCount);
	}

	@Override
	public void onMeterRemoved(String name) {
		throw new RuntimeException("Method not implemented");
	}

	@Override
	public void onTimerAdded(String name, Timer timer) {
		meterRegistry.more().timer(name, Tags.empty(), timer, Timer::getCount, DropwizardToMicrometerBridge::totalTime, TimeUnit.MILLISECONDS);
	}

	@Override
	public void onTimerRemoved(String name) {
		throw new RuntimeException("Method not implemented");
	}

	public static long totalTime(Sampling sampling) {
		return Arrays.stream(sampling.getSnapshot().getValues()).sum();
	}

	public static double doubleValue(Gauge<?> gauge) {
		if (gauge == null || gauge.getValue() == null) {
			return Double.NaN;
		}
		Object value = gauge.getValue();
		return Double.valueOf(value.toString());
	}

}

HdrReservoir throws an UnsupportedOperationException in totalTime so i had to modify it to:
Turns out HdrReservoir is something from the cassandra java driver so not applicable to all :)

    public static long totalTime(Sampling sampling) {
        if (sampling instanceof HdrReservoir) {
            return -1;
        } else {
            return Arrays.stream(sampling.getSnapshot().getValues()).sum();
        }
    }

Thank you so much for sharing this! 👍