HDDS-678. Format of Last-Modified header is invalid in HEAD Object call. Contributed by Elek Marton.

hadoop-ozone/s3gateway/src/main/java/org/apache/hadoop/ozone/s3/endpoint/ObjectEndpoint.java

@@ -34,6 +34,10 @@ import javax.ws.rs.core.Response.Status;
 import javax.ws.rs.core.StreamingOutput;
 import java.io.IOException;
 import java.io.InputStream;
+import java.time.Instant;
+import java.time.ZoneId;
+import java.time.ZonedDateTime;
+import java.time.format.DateTimeFormatter;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -180,8 +184,13 @@ public class ObjectEndpoint extends EndpointBase {
       }
     }
 
+    ZonedDateTime lastModificationTime =
+        Instant.ofEpochMilli(key.getModificationTime())
+            .atZone(ZoneId.of("GMT"));
+
     return Response.ok().status(HttpStatus.SC_OK)
-        .header("Last-Modified", key.getModificationTime())
+        .header("Last-Modified",
+            DateTimeFormatter.RFC_1123_DATE_TIME.format(lastModificationTime))
         .header("ETag", "" + key.getModificationTime())
         .header("Content-Length", key.getDataSize())
         .header("Content-Type", "binary/octet-stream")

hadoop-ozone/s3gateway/src/test/java/org/apache/hadoop/ozone/s3/endpoint/TestObjectHead.java

@@ -21,6 +21,7 @@ package org.apache.hadoop.ozone.s3.endpoint;
 
 import javax.ws.rs.core.Response;
 import java.io.IOException;
+import java.time.format.DateTimeFormatter;
 
 import org.apache.hadoop.hdds.client.ReplicationFactor;
 import org.apache.hadoop.hdds.client.ReplicationType;
@@ -80,6 +81,10 @@ public class TestObjectHead {
     Assert.assertEquals(200, response.getStatus());
     Assert.assertEquals(value.getBytes().length,
         Long.parseLong(response.getHeaderString("Content-Length")));
+
+    DateTimeFormatter.RFC_1123_DATE_TIME
+        .parse(response.getHeaderString("Last-Modified"));
+
   }
 
   @Test