# Dropwizard — Production-Ready Java REST Framework

> An opinionated Java framework that bundles Jetty, Jersey, Jackson, and Metrics into a single package for building RESTful web services.

## Install

Save the content below to `.claude/skills/` or append to your `CLAUDE.md`:

# Dropwizard — Production-Ready Java REST Framework

## Quick Use
```bash
mvn archetype:generate 
  -DarchetypeGroupId=io.dropwizard.archetypes 
  -DarchetypeArtifactId=java-simple 
  -DarchetypeVersion=4.0.0
cd my-app
mvn package
java -jar target/my-app-1.0.0.jar server config.yml
```

## Introduction
Dropwizard is a Java framework for developing ops-friendly, high-performance RESTful web services. Instead of assembling components yourself, Dropwizard packages battle-tested libraries — Jetty for HTTP, Jersey for REST, Jackson for JSON, and Metrics for monitoring — into a cohesive stack with sensible defaults.

## What Dropwizard Does
- Runs as a self-contained fat JAR with an embedded Jetty server
- Exposes RESTful endpoints using JAX-RS (Jersey) annotations
- Serializes and deserializes JSON with Jackson, including validation via Hibernate Validator
- Collects operational metrics (timers, counters, health checks) out of the box
- Manages database connections through JDBI or Hibernate bundles

## Architecture Overview
A Dropwizard application is a standard Java `main()` method that initializes the framework, reads a YAML configuration file, and starts an embedded Jetty server. The application registers resource classes (JAX-RS endpoints), health checks, and managed lifecycle objects. Two separate Jetty connectors serve application traffic and an admin interface (metrics, health checks, thread dumps) on different ports. Configuration is type-safe: YAML keys map to Java objects validated at startup.

## Self-Hosting & Configuration
- Requires JDK 11+ and Maven or Gradle for building
- Application settings are defined in a YAML file passed as a command-line argument
- Environment variables can override YAML values using the `SubstitutingSourceProvider`
- Build a fat JAR with `mvn package` and run directly with `java -jar`
- Deploy as a systemd service, Docker container, or on any JVM-hosting platform

## Key Features
- Admin port exposes health checks, thread dumps, and Prometheus-compatible metrics
- Configuration validation catches misconfigurations at startup, not at runtime
- Views bundle supports server-rendered HTML with Mustache or Freemarker templates
- Authentication filters for Basic, OAuth2, and custom auth schemes
- Lifecycle management for background tasks, scheduled jobs, and graceful shutdown

## Comparison with Similar Tools
- **Spring Boot** — Larger ecosystem with auto-configuration; Dropwizard is more explicit and produces smaller binaries
- **Quarkus** — GraalVM native compilation for fast startup; Dropwizard uses traditional JVM with proven library choices
- **Micronaut** — Compile-time DI and low memory; Dropwizard relies on runtime reflection but has a simpler mental model
- **Vert.x** — Reactive and polyglot; Dropwizard is blocking by design with thread-per-request simplicity

## FAQ
**Q: Is Dropwizard still actively maintained?**
A: Yes. Dropwizard 4.x is the current major version with ongoing development and releases.

**Q: How does Dropwizard handle dependency injection?**
A: Dropwizard uses HK2 (bundled with Jersey) for DI. Community bundles add Guice or Dagger support.

**Q: Can Dropwizard serve a single-page application?**
A: Yes. The assets bundle serves static files from the classpath, and you can configure a fallback to `index.html` for client-side routing.

**Q: What is the admin port used for?**
A: The admin connector (default port 8081) serves operational endpoints: health checks, metrics, CPU profiles, and log-level management — separate from application traffic.

## Sources
- https://github.com/dropwizard/dropwizard
- https://www.dropwizard.io

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Source: https://tokrepo.com/en/workflows/dropwizard-production-ready-java-rest-framework-5a8cdf92
Author: AI Open Source