MTDSA-32419: Return 504 GATEWAY_TIMEOUT for 499s and 504s from downstream (#205)

Author: omotrium

app/shared/models/errors/CommonMtdErrors.scala

@@ -58,6 +58,8 @@ object InternalError extends MtdError("INTERNAL_SERVER_ERROR", "An internal serv
 
 object BadRequestError extends MtdError("INVALID_REQUEST", "Invalid request", BAD_REQUEST)
 
+object GatewayTimeoutError extends MtdError("GATEWAY_TIMEOUT", "The request has timed out", GATEWAY_TIMEOUT)
+
 object BVRError extends MtdError("BUSINESS_ERROR", "Business validation error", BAD_REQUEST)
 
 object InvalidHttpMethodError extends MtdError("INVALID_HTTP_METHOD", "Invalid HTTP method", METHOD_NOT_ALLOWED)

app/shared/utils/ErrorHandler.scala

@@ -97,11 +97,15 @@ class ErrorHandler @Inject() (
       ex
     )
 
+    val NGINX_TIMEOUT                = 499
+    val timeoutStatusCodes: Set[Int] = Set(NGINX_TIMEOUT, GATEWAY_TIMEOUT)
+
     val (errorCode, eventType) = ex match {
-      case _: NotFoundException      => (NotFoundError, "ResourceNotFound")
-      case _: AuthorisationException => (ClientOrAgentNotAuthorisedError.withStatus401, "ClientError")
-      case _: JsValidationException  => (BadRequestError, "ServerValidationError")
-      case e: HttpException          => (BadRequestError, "ServerValidationError")
+      case _: NotFoundException                                                  => (NotFoundError, "ResourceNotFound")
+      case _: AuthorisationException                                             => (ClientOrAgentNotAuthorisedError.withStatus401, "ClientError")
+      case _: JsValidationException                                              => (BadRequestError, "ServerValidationError")
+      case e: HttpException                                                      => (BadRequestError, "ServerValidationError")
+      case e: UpstreamErrorResponse if timeoutStatusCodes.contains(e.statusCode) => (GatewayTimeoutError, "ServerTimeoutError")
       case e: UpstreamErrorResponse if UpstreamErrorResponse.Upstream4xxResponse.unapply(e).isDefined =>
         (BadRequestError, "ServerValidationError")
       case e: UpstreamErrorResponse if UpstreamErrorResponse.Upstream5xxResponse.unapply(e).isDefined =>

test/shared/utils/ErrorHandlerSpec.scala

@@ -156,6 +156,18 @@ class ErrorHandlerSpec extends UnitSpec with GuiceOneAppPerSuite {
         status(result) shouldBe INTERNAL_SERVER_ERROR
         contentAsJson(result) shouldBe InternalError.asJson
       }
+
+      "return GATEWAY_TIMEOUT with error body" when {
+        Seq(499, GATEWAY_TIMEOUT).foreach { statusCode =>
+          s"a $statusCode UpstreamErrorResponse is returned" in new Test {
+            val errorResponse: UpstreamErrorResponse = UpstreamErrorResponse("request timeout", statusCode, statusCode, Map.empty)
+            val result: Future[Result]               = handler.onServerError(requestHeader, errorResponse)
+
+            status(result) shouldBe GATEWAY_TIMEOUT
+            contentAsJson(result) shouldBe GatewayTimeoutError.asJson
+          }
+        }
+      }
     }
   }