chore: endpoint request header follow up and docs (#115)

akka-javasdk/src/main/java/akka/javasdk/http/RequestContext.java

@@ -5,11 +5,15 @@
 package akka.javasdk.http;
 
 import akka.annotation.DoNotInherit;
+import akka.http.javadsl.model.HttpHeader;
 import akka.javasdk.Context;
 import akka.javasdk.JwtClaims;
 import akka.javasdk.Principals;
 import akka.javasdk.Tracing;
 
+import java.util.List;
+import java.util.Optional;
+
 /**
  * Not for user extension, can be injected as constructor parameter into HTTP endpoint components or
  * accessible from {@link AbstractHttpEndpoint#requestContext()} if the endpoint class extends
@@ -28,6 +32,15 @@ public interface RequestContext extends Context {
   /** @return The JWT claims, if any, associated with this request. */
   JwtClaims getJwtClaims();
 
+  /**
+   * @return A header with the given name (case ignored) if present in the current request,
+   *     Optional.empty() if not.
+   */
+  Optional<HttpHeader> requestHeader(String headerName);
+
+  /** @return A list with all the headers of the current request */
+  List<HttpHeader> allRequestHeaders();
+
   /** Access to tracing for custom app specific tracing. */
   Tracing tracing();
 }

akka-javasdk/src/main/scala/akka/javasdk/impl/SdkRunner.scala

@@ -8,7 +8,6 @@ import java.lang.reflect.Constructor
 import java.lang.reflect.InvocationTargetException
 import java.lang.reflect.Method
 import java.util.concurrent.CompletionStage
-
 import scala.annotation.nowarn
 import scala.concurrent.ExecutionContext
 import scala.concurrent.Future
@@ -18,10 +17,10 @@ import scala.jdk.FutureConverters._
 import scala.jdk.OptionConverters.RichOptional
 import scala.reflect.ClassTag
 import scala.util.control.NonFatal
-
 import akka.Done
 import akka.actor.typed.ActorSystem
 import akka.annotation.InternalApi
+import akka.http.javadsl.model.HttpHeader
 import akka.http.scaladsl.model.headers.RawHeader
 import akka.javasdk.BuildInfo
 import akka.javasdk.DependencyProvider
@@ -96,6 +95,10 @@ import org.slf4j.Logger
 import org.slf4j.LoggerFactory
 import org.slf4j.event.Level
 
+import java.util
+import java.util.Optional
+import scala.jdk.OptionConverters.RichOption
+
 /**
  * INTERNAL API
  */
@@ -667,6 +670,14 @@ private final class Sdk(
                 "There are no JWT claims defined but trying accessing the JWT claims. The class or the method needs to be annotated with @JWT.")
           }
 
+        override def requestHeader(headerName: String): Optional[HttpHeader] =
+          // Note: force cast to Java header model
+          context.requestHeaders.header(headerName).asInstanceOf[Option[HttpHeader]].toJava
+
+        override def allRequestHeaders(): util.List[HttpHeader] =
+          // Note: force cast to Java header model
+          context.requestHeaders.allHeaders.asInstanceOf[Seq[HttpHeader]].asJava
+
         override def tracing(): Tracing = new SpanTracingImpl(context.openTelemetrySpan, sdkTracerFactory)
       }
       val instance = wiredInstance(httpEndpointClass) {

docs/src/modules/java/pages/http-endpoints.adoc

@@ -244,3 +244,17 @@ include::example$doc-snippets/src/main/java/com/example/api/ExampleEndpoint.java
 <1> Accept the materializer and keep it in a field
 <2> Make sure to discard the request body when failing
 <3> Or collect the bytes into memory
+
+
+ === Accessing request headers ===
+
+ Accessing request headers is done through the link:_attachments/api/akka/javasdk/http/RequestContext.html[RequestContext] methods `requestHeader(String headerName)` and `allRequestHeaders()`.
+
+ By letting the endpoint extend link:_attachments/api/akka/javasdk/http/AbstractHttpEndpoint.html[AbstractHttpEndpoint] request context is available through the method `requestContext()`.
+
+ [source,java]
+ .{sample-base-url}/doc-snippets/src/main/java/com/example/api/ExampleEndpoint.java[ExampleEndpoint.java]
+ ----
+ include::example$doc-snippets/src/main/java/com/example/api/ExampleEndpoint.java[tag=header-access]
+ ----
+ <1> `requestHeader(headerName)` returns an `Optional` which is empty if the header was not present.