[SPARK-24660][SHS] Show correct error pages when downloading logs

core/src/main/scala/org/apache/spark/status/api/v1/ApiRootResource.scala

@@ -28,7 +28,7 @@ import org.glassfish.jersey.server.ServerProperties
 import org.glassfish.jersey.servlet.ServletContainer
 
 import org.apache.spark.SecurityManager
-import org.apache.spark.ui.SparkUI
+import org.apache.spark.ui.{SparkUI, UIUtils}
 
 /**
  * Main entry point for serving spark application metrics as json, using JAX-RS.
@@ -148,38 +148,18 @@ private[v1] trait BaseAppResource extends ApiRequestContext {
 }
 
 private[v1] class ForbiddenException(msg: String) extends WebApplicationException(
-  Response.status(Response.Status.FORBIDDEN).entity(msg).build())
+    UIUtils.buildErrorResponse(Response.Status.FORBIDDEN, msg))
 
 private[v1] class NotFoundException(msg: String) extends WebApplicationException(
-  new NoSuchElementException(msg),
-    Response
-      .status(Response.Status.NOT_FOUND)
-      .entity(ErrorWrapper(msg))
-      .build()
-)
+    UIUtils.buildErrorResponse(Response.Status.NOT_FOUND, msg))
 
 private[v1] class ServiceUnavailable(msg: String) extends WebApplicationException(
-  new ServiceUnavailableException(msg),
-  Response
-    .status(Response.Status.SERVICE_UNAVAILABLE)
-    .entity(ErrorWrapper(msg))
-    .build()
-)
+    UIUtils.buildErrorResponse(Response.Status.SERVICE_UNAVAILABLE, msg))
 
 private[v1] class BadParameterException(msg: String) extends WebApplicationException(
-  new IllegalArgumentException(msg),
-  Response
-    .status(Response.Status.BAD_REQUEST)
-    .entity(ErrorWrapper(msg))
-    .build()
-) {
+    UIUtils.buildErrorResponse(Response.Status.BAD_REQUEST, msg)) {
   def this(param: String, exp: String, actual: String) = {
     this(raw"""Bad value for parameter "$param".  Expected a $exp, got "$actual"""")
   }
 }
 
-/**
- * Signal to JacksonMessageWriter to not convert the message into json (which would result in an
- * extra set of quotes).
- */
-private[v1] case class ErrorWrapper(s: String)

core/src/main/scala/org/apache/spark/status/api/v1/JacksonMessageWriter.scala

@@ -68,10 +68,7 @@ private[v1] class JacksonMessageWriter extends MessageBodyWriter[Object]{
       mediaType: MediaType,
       multivaluedMap: MultivaluedMap[String, AnyRef],
       outputStream: OutputStream): Unit = {
-    t match {
-      case ErrorWrapper(err) => outputStream.write(err.getBytes(StandardCharsets.UTF_8))
-      case _ => mapper.writeValue(outputStream, t)
-    }
+    mapper.writeValue(outputStream, t)
   }
 
   override def getSize(

core/src/main/scala/org/apache/spark/status/api/v1/OneApplicationResource.scala

@@ -140,11 +140,8 @@ private[v1] class AbstractApplicationResource extends BaseAppResource {
         .header("Content-Type", MediaType.APPLICATION_OCTET_STREAM)
         .build()
     } catch {
-      case NonFatal(e) =>
-        Response.serverError()
-          .entity(s"Event logs are not available for app: $appId.")
-          .status(Response.Status.SERVICE_UNAVAILABLE)
-          .build()
+      case NonFatal(_) =>
+        throw new ServiceUnavailable(s"Event logs are not available for app: $appId.")
     }
   }
 

core/src/main/scala/org/apache/spark/ui/UIUtils.scala

@@ -21,6 +21,7 @@ import java.net.URLDecoder
 import java.text.SimpleDateFormat
 import java.util.{Date, Locale, TimeZone}
 import javax.servlet.http.HttpServletRequest
+import javax.ws.rs.core.{MediaType, Response}
 
 import scala.util.control.NonFatal
 import scala.xml._
@@ -566,4 +567,8 @@ private[spark] object UIUtils extends Logging {
         NEWLINE_AND_SINGLE_QUOTE_REGEX.replaceAllIn(requestParameter, ""))
     }
   }
+
+  def buildErrorResponse(status: Response.Status, msg: String): Response = {
+    Response.status(status).entity(msg).`type`(MediaType.TEXT_PLAIN).build()
+  }
 }