Smallrye open api interceptor - swagger

Question

I am developing a rest application.
Some endpoints require a custom header parameter, not related to authorisation. I created a custom annotation using jax-rs NameBinding. Here is an usage example:
#GET
#RequiresBankHeader
public int get(
#HeaderParam("bank")
#Parameter(ref = "#/components/parameters/banks")
String bank) {
return someService.getSomeInformation();
}
There is a provider that intercepts this call and do some routine using the information in the header parameter.
The problem is that I have to repeat '#HeaderParam("bank") #Parameter(ref = "#/components/parameters/banks") String bank' everywhere, just so it appears in Swagger, even though the service classes do not need it. I was able to at least reuse the parameter definition with ref = "#/components/parameters/banks", and declaring it in the OpenAPI.yml file, that Quarkus merges with generated code very nicely.
But I also want to create and interceptor to dynamically add this do the OpenApi definition whenever RequiresBankHeader annotation is present.
Is there a way to do it?

Answer 1

I dont think you can use interceptors to modify the generated Openapi schema output.
If all methods on a given endpoint require some parameter, you can specify it on class level like so:
#Path("/someendpoint")
public class MyEndpoint {
#HeaderParam("bank")
#Parameter(name = "bank")
String bank;
#GET
public Response getAll() {return Response.ok().build()}
#GET
#Path("{id}")
public Response someMethod(#PathParam("id") String id) {return Response.ok().build();}
}

Answer 2

As mentioned by Roberto Cortez, the MP OpenAPI spec provides a programmatic way to contribute metadata to the openapi.yml file.
It is not possible to detect an annotation in the JAX-RS endpoint definition, but it was good enough to automate what I needed. Since all methods that had the RequiresBankHeader return the same Schema, I was able to hack it like this:
public class OpenApiConfigurator implements OASFilter {
#Override
public Operation filterOperation(Operation operation) {
operation.getResponses().getAPIResponses().values().stream().
map(APIResponse::getContent).
filter(Objects::nonNull).
map(Content::getMediaTypes).
flatMap(mediaTypes -> mediaTypes.values().stream()).
map(MediaType::getSchema).
filter(Objects::nonNull).
map(Schema::getRef).
filter(Objects::nonNull).
filter(ref -> ref.contains("the common response schema")).
findAny().
ifPresent(schema -> {
ParameterImpl parameter = new ParameterImpl();
parameter.setRef("#/components/parameters/banks");
operation.addParameter(parameter);
});
return operation;
}
OpenApiConfigurator should be configure in the application properties, using mp.openapi.filter=com.yourcompany.OpenApiConfigurator