Issue: Dropwizard 5 instrumentation does not collect HTTP metrics correctly

[thiagohora]

Describe the bug

After upgrading to Dropwizard 5, HTTP server metrics are not being collected or exposed correctly. The application starts without errors, but expected HTTP-related metrics (e.g., request counts, latency timers, request body size) are missing or incomplete.

Expected Behavior
Dropwizard’s built-in instrumentation should automatically register:

• request duration timers
• request/response size meters
• per-endpoint and per-status-code metrics (e.g., io.dropwizard.jetty.MutableServletContextHandler.requests.)

Metrics should appear under the configured metrics backend (Prometheus, console, JMX, etc.).

Actual Behavior

• No HTTP server metrics are reported.
• Request/response metrics are missing.

Steps to reproduce

• Create a minimal Dropwizard 5 application:
  • One simple resource, e.g. GET /ping returning "pong".
• Configure the server in config.yml with virtual threads disabled:

server:
  type: default
  enableVirtualThreads: false

• Start the application with the OpenTelemetry Java agent, for example:

java \
  -javaagent:/path/to/opentelemetry-javaagent.jar \
  -Dotel.service.name=dropwizard-test \
  -Dotel.exporter.otlp.endpoint=http://localhost:4317 \
  -jar target/app.jar server config.yml

• Send some traffic to the app:

curl http://localhost:8080/ping
# repeat many times or run a small load test

• Check the metrics/exported data in your backend (Prometheus / OTLP collector / logs):
  • You will see traces and some metrics, but expected HTTP server metrics are missing or not updated.
• Now change the configuration to:

server:
  type: default
  enableVirtualThreads: true

• Restart the app with the same OTEL agent configuration, send the same traffic, and check metrics again:
  • HTTP metrics appear to be collected correctly or at least more reliably than with enableVirtualThreads = false.

Expected behavior

Collect all metrics correctly

Actual behavior

The vast majority of the metrics are not collected.

Javaagent or library instrumentation version

2.21.0

Environment

JDK: 21.0.8 Correto
OS: amazon linux
DW 5.0.0

Additional context

No response

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[laurit]

Please provide a minimal sample application that reproduces your issue along with any necessary instructions.

[thiagohora]

Hi @laurit,

Here is sample app which reproduce the issue; https://github.com/thiagohora/sample-dw-app-otel