Quarkus Application Development

From the author

Write Quarkus application code: REST with Quarkus REST, validation, exception mappers, OpenAPI, configuration, CDI (ArC), Hibernate ORM with Panache, Mutiny and virtual threads, Reactive Messaging with Kafka, OIDC security, health, metrics, OpenTelemetry, fault tolerance, REST Client, scheduler and cache. Use when implementing or changing features in an existing Quarkus project.

— the description by jdubois

AutoGineer summary

Written by AutoGineer from the skill’s own files, not by the author

This skill provides a structured approach to developing application code within a Quarkus project. It covers the integration of essential extensions such as Hibernate ORM with Panache, REST services, security via OIDC, observability, and messaging with Kafka. The skill emphasizes adherence to Quarkus-specific patterns, such as build-time CDI resolution, proper configuration management, and the use of Dev Services for testing, while ensuring developers avoid common pitfalls like blocking the event loop or hard-coding secrets.

What it does

Guides the addition of Quarkus extensions using standard CLI commands.
Provides patterns for REST API development, including validation and exception handling.
Offers best practices for CDI bean management and configuration using @ConfigMapping.
Outlines implementation strategies for observability, resilience, and scheduling.
Ensures secure development by advising against hard-coded secrets and promoting OIDC integration.
Helps troubleshoot common Quarkus-specific issues like bean removal and event loop blocking.

When to use it

When implementing new features or modifying existing logic in a Quarkus application.
When integrating new infrastructure dependencies like Kafka or OIDC.
When configuring application properties or setting up observability and fault tolerance.
When debugging issues related to CDI, bean scopes, or blocking operations.

Advantages

Promotes consistent use of Quarkus-idiomatic code and Jakarta EE standards.
Reduces development time by providing verified patterns for common integration tasks.
Helps maintain application performance by highlighting event loop and blocking constraints.
Ensures project stability by leveraging build-time validation and proper configuration management.

Usage examples

“How do I add a REST endpoint that uses Hibernate Panache to fetch data from a database?”: The agent will guide you to add the quarkus-hibernate-orm-panache extension, define a PanacheEntity, and create a REST resource that injects the repository or uses the active record pattern.
“I need to add a scheduled task that runs every hour. How should I implement this?”: The agent will advise using the @Scheduled annotation on a bean method and suggest configuring the interval or cron expression via application properties.

Install

Download the skill as a ZIP:
https://autogineer.com/agent-skills/github/quarkus-application-development/download

Unzip it into the cross-client skills folder of your project:

mkdir -p .agents/skills && unzip quarkus-application-development.zip -d .agents/skills

Documentation by jdubois

Scope: application code inside an existing Quarkus project. Project creation is create-quarkus-project; Dev Services and tests are quarkus-dev-services-and-testing; native and container images are quarkus-native-and-container; core JPA mapping and query design can use the optional java-hibernate-jpa skill if installed (otherwise see the Hibernate ORM guide, https://quarkus.io/guides/hibernate-orm, and the Jakarta Persistence docs).

Agent rules

Detect first: read pom.xml/build.gradle for quarkus.platform.version, the Java release, and the extensions already present. Keep the version; use what the project already uses (for example quarkus-resteasy* stays if present).
Add extensions with quarkus extension add <name> or ./mvnw quarkus:add-extension -Dextensions=<name>; never guess artifact ids or versions by hand (the platform BOM manages them). List candidates with quarkus extension list --installable --search=<text>.
Ask the user before adding Kafka, OIDC/Keycloak or any new infrastructure dependency (they start containers in dev/test and change deployment needs).
Never use the Spring compatibility extensions (quarkus-spring-*) unless the project already does.
Verify with dev mode (./mvnw quarkus:dev, then /q/dev-ui) and ./mvnw verify; write a @QuarkusTest per feature. Do not claim something works without running it.
Use jakarta.* imports, records for DTOs, thin resources delegating to services.
Never hard-code secrets or add credentials to application.properties; see references/config-cdi.md.

Quick decisions

Need	Use	Details
JSON REST API	`quarkus-rest-jackson`, `quarkus-hibernate-validator`, `quarkus-smallrye-openapi`	`references/rest.md`
Typed config	`@ConfigMapping`; `@ConfigProperty` for single values	`references/config-cdi.md`
Beans	`@ApplicationScoped` (default), `@Singleton` only for plain stateless holders	`references/config-cdi.md`
Database	`quarkus-hibernate-orm-panache` + JDBC driver, repository pattern	`references/persistence.md`
Async / blocking	Imperative by default; `@RunOnVirtualThread` or `Uni` when needed	`references/reactive-messaging.md`
Messaging	`quarkus-messaging-kafka` (SmallRye Reactive Messaging)	`references/reactive-messaging.md`
AuthN/AuthZ	`quarkus-oidc`, `@RolesAllowed`	`references/security-oidc.md`
Ops	`quarkus-smallrye-health`, `quarkus-micrometer-registry-prometheus`, `quarkus-opentelemetry`, `quarkus-smallrye-fault-tolerance`	`references/observability-resilience.md`
Outbound HTTP, scheduling, caching	`quarkus-rest-client-jackson`, `quarkus-scheduler`, `quarkus-cache`	`references/observability-resilience.md`

Pitfalls that cost time

Quarkus resolves CDI at build time: an unused bean may be removed. Beans only looked up programmatically need @Unremovable.
Do not read or write public fields of a normal-scoped bean (@ApplicationScoped) from another bean or test: you hit the client proxy, not the instance (verified: a counter field read through the proxy returned 0). Use methods.
Do not block on the event loop (@NonBlocking methods, Uni/Multi return types running on I/O threads). Remove any existing @NonBlocking from the method (combining it with @Blocking or @RunOnVirtualThread fails the build), then add @Blocking or @RunOnVirtualThread (see references/reactive-messaging.md).
Changes to build-time properties need a rebuild; run-time properties can be overridden by env vars (QUARKUS_DATASOURCE_JDBC_URL).
Do not configure URLs for databases/brokers/Keycloak in %dev/%test: that disables Dev Services.
drop-and-create schema management is for dev/test only; use Flyway or Liquibase for production.

Verified on Quarkus 3.40.1 and 3.27.6 (Java 21 target, Maven) with a scaffolded app and mvn verify (15 tests: REST+validation+mapper, OpenAPI, config mapping, Panache on PostgreSQL Dev Services, Kafka Dev Service round trip, Keycloak Dev Service tokens, health, metrics, fault tolerance, cache, scheduler). Re-check names against the project's version.

Files

ATTRIBUTION.mdAdded by AutoGineer893 B
LICENSELicence file added by AutoGineer1.0 KiB
SKILL.md4.5 KiB
references/config-cdi.md5.5 KiB
references/observability-resilience.md4.5 KiB
references/persistence.md4.9 KiB
references/reactive-messaging.md4.2 KiB
references/rest.md2.8 KiB
references/security-oidc.md3.1 KiB

Requirements and compatibility

Written for: GitHub Copilot

Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta

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