Add CORS support for functional style routes for WebFlux [SPR-15567]

[spring-projects-issues]

Sumanth Chinthagunta opened SPR-15567 and commented

We have annotations support for adding CORS to routes but I cannot find support for adding CORS for functional style routes when using WebFlux.
This capability is critical for consuming REST , SSE APIs from external SPA apps build with Angular or React.

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Affects: 5.0 RC1

Issue Links:

• CORS Options request forbidden with Webflux [SPR-15704] #20261 CORS Options request forbidden with Webflux

Referenced from: commits 1e04cdf

[spring-projects-issues]

Sébastien Deleuze commented

Indeed, that makes sense, maybe via a CORS WebFilter.

[spring-projects-issues]

Sébastien Deleuze commented

Fixed via the introduction of [CorsWebFilter](https://github.com/spring-projects/spring-framework/commit/1e04cdfa7e3ac74181efe57e0674abe4690c46a1).

[spring-projects-issues]

Sébastien Deleuze commented

I reopen this issue since a cors(CorsConfigurationSource source) method would also make sense in HandlerStrategies.Builder since as of this commit the functional router leverage @EnableWebFlux infrastracture.

Notice that it is already also possible to configure it via @EnableWebFlux + overriding WebFluxConfigurer#addCorsMappings but a dedicated way of configuring it without annotations or WebCorsFilter seems worth to provide.

[spring-projects-issues]

Sébastien Deleuze commented

After a deeper look I think what we have currently is in fact ok. WebFilter based approach should be used via HandlerStrategies.Builder for standelone WebFlux server use case, and @EnableWebFlux + overriding WebFluxConfigurer#addCorsMappings is fine for other use cases like Spring Boot apps.