Populating Headers Using Configuration

The @Header annotation can be declared at the type level and is repeatable such that it is possible to drive the request headers sent via configuration using annotation metadata.

The following example serves to illustrate this:

Defining Headers via Configuration

@Client("/pets")
@Header(name="X-Pet-Client", value="${pet.client.id}")
public interface PetClient extends PetOperations {
    @Override
    @SingleResult
    Publisher<Pet> save(String name, int age);
    @Get("/{name}")
    @SingleResult
    Publisher<Pet> get(String name);
}

Defining Headers via Configuration

@Client("/pets")
@Header(name="X-Pet-Client", value='${pet.client.id}')
interface PetClient extends PetOperations {
    @Override
    @SingleResult
    Publisher<Pet> save(@NotBlank String name, @Min(1L) int age)
    @Get("/{name}")
    @SingleResult
    Publisher<Pet> get(String name)
}

Defining Headers via Configuration

@Client("/pets")
@Header(name = "X-Pet-Client", value = "\${pet.client.id}")
interface PetClient : PetOperations {
    @SingleResult
    override fun save(name: String, age: Int): Publisher<Pet>
    @Get("/{name}")
    @SingleResult
    operator fun get(name: String): Publisher<Pet>
}

The above example defines a @Header annotation on the PetClient interface that reads the pet.client.id property using property placeholder configuration.

Then set the following in application.yml to populate the value:

Configuring Headers in YAML

pet:
  client:
    id: foo

Alternatively you can supply a PET_CLIENT_ID environment variable and the value will be populated.