What is the role of the Quarkus Arc container?

ArC is Quarkus's own CDI-compliant dependency injection container, purpose-built to resolve as much of the bean discovery and wiring process as possible during build-time augmentation instead of through runtime classpath scanning like a traditional CDI implementation.

Its role spans the whole DI lifecycle: during the build, ArC's build steps discover CDI beans (via @Inject, scopes, producers, and qualifiers), validate the dependency graph for missing or ambiguous dependencies, and generate the bytecode needed to create and wire bean instances efficiently; at runtime, that pre-generated code creates bean instances on demand according to their configured scope, with no further reflective scanning required.

Because ArC targets full compatibility with the CDI specification while remaining native-image friendly, developers get the familiar CDI programming model — the same annotations, the same scoping rules — without needing to learn a Quarkus-specific dependency injection API, while still getting the startup and native-image benefits that a fully dynamic, general-purpose CDI implementation couldn't offer.