better exception for invalid interval

server/src/main/java/io/druid/server/http/DatasourcesResource.java

@@ -166,6 +166,12 @@ public class DatasourcesResource
     return Response.ok().build();
   }
 
+  /* When this method is removed, a new method needs to be introduced corresponding to
+    the end point "DELETE /druid/coordinator/v1/datasources/{dataSourceName}" (with no query parameters).
+    Ultimately we want to have no method with kill parameter -
+    DELETE `{dataSourceName}` will be used to disable datasource and
+    DELETE `{dataSourceName}/intervals/{interval}` will be used to nuke segments
+  */
   @DELETE
   @Deprecated
   @Path("/{dataSourceName}")
@@ -179,15 +185,30 @@ public class DatasourcesResource
     if (indexingServiceClient == null) {
       return Response.ok(ImmutableMap.of("error", "no indexing service found")).build();
     }
+
     if (kill != null && Boolean.valueOf(kill)) {
       try {
         indexingServiceClient.killSegments(dataSourceName, new Interval(interval));
       }
+      catch (IllegalArgumentException e) {
+        return Response.status(Response.Status.BAD_REQUEST)
+                       .entity(
+                           ImmutableMap.of(
+                               "error",
+                               "Exception occurred. Probably the interval is invalid",
+                               "message",
+                               e.toString()
+                           )
+                       )
+                       .build();
+      }
       catch (Exception e) {
         return Response.serverError().entity(
             ImmutableMap.of(
                 "error",
-                "Exception occurred. Are you sure you have an indexing service?"
+                "Exception occurred. Are you sure you have an indexing service?",
+                "message",
+                e.toString()
             )
         )
                        .build();
@@ -220,7 +241,9 @@ public class DatasourcesResource
       return Response.serverError()
                      .entity(ImmutableMap.of(
                          "error",
-                         "Exception occurred. Are you sure you have an indexing service?"
+                         "Exception occurred. Are you sure you have an indexing service?",
+                         "message",
+                         e.toString()
                      ))
                      .build();
     }

server/src/test/java/io/druid/server/http/DatasourcesResourceTest.java

@@ -403,4 +403,17 @@ public class DatasourcesResourceTest
     EasyMock.verify(indexingServiceClient, server);
   }
 
+  @Test
+  public void testDeleteDataSource() {
+    IndexingServiceClient indexingServiceClient = EasyMock.createStrictMock(IndexingServiceClient.class);
+    EasyMock.replay(indexingServiceClient, server);
+    DatasourcesResource datasourcesResource = new DatasourcesResource(inventoryView, null, indexingServiceClient);
+    Response response = datasourcesResource.deleteDataSource("datasource", "true", "???");
+    Assert.assertEquals(400, response.getStatus());
+    Assert.assertNotNull(response.getEntity());
+    Assert.assertTrue(response.getEntity().toString().contains("java.lang.IllegalArgumentException"));
+
+    EasyMock.verify(indexingServiceClient, server);
+  }
+
 }