From d16d00558264a96e38c2ee03456b697dd21f18a9 Mon Sep 17 00:00:00 2001
From: Joe Reuter <johannes.reuter@elastic.co>
Date: Wed, 28 Oct 2020 10:11:37 +0100
Subject: [PATCH] Log reason for 404 in field existence check (#81315) (#81743)

---
 x-pack/plugins/lens/server/plugin.tsx         |  4 ++--
 .../lens/server/routes/existing_fields.ts     | 19 +++++++++++++------
 x-pack/plugins/lens/server/routes/index.ts    |  6 +++---
 3 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/x-pack/plugins/lens/server/plugin.tsx b/x-pack/plugins/lens/server/plugin.tsx
index b801d30f5ba9b..a8f9bef92349c 100644
--- a/x-pack/plugins/lens/server/plugin.tsx
+++ b/x-pack/plugins/lens/server/plugin.tsx
@@ -29,13 +29,13 @@ export class LensServerPlugin implements Plugin<{}, {}, {}, {}> {
   private readonly kibanaIndexConfig: Observable<{ kibana: { index: string } }>;
   private readonly telemetryLogger: Logger;
 
-  constructor(initializerContext: PluginInitializerContext) {
+  constructor(private initializerContext: PluginInitializerContext) {
     this.kibanaIndexConfig = initializerContext.config.legacy.globalConfig$;
     this.telemetryLogger = initializerContext.logger.get('usage');
   }
   setup(core: CoreSetup<PluginStartContract>, plugins: PluginSetupContract) {
     setupSavedObjects(core);
-    setupRoutes(core);
+    setupRoutes(core, this.initializerContext.logger.get());
     if (plugins.usageCollection && plugins.taskManager) {
       registerLensUsageCollector(
         plugins.usageCollection,
diff --git a/x-pack/plugins/lens/server/routes/existing_fields.ts b/x-pack/plugins/lens/server/routes/existing_fields.ts
index c925517b572da..d3b2314a199cb 100644
--- a/x-pack/plugins/lens/server/routes/existing_fields.ts
+++ b/x-pack/plugins/lens/server/routes/existing_fields.ts
@@ -7,10 +7,14 @@
 import Boom from 'boom';
 import { schema } from '@kbn/config-schema';
 import { ILegacyScopedClusterClient, SavedObject, RequestHandlerContext } from 'src/core/server';
-import { CoreSetup } from 'src/core/server';
+import { CoreSetup, Logger } from 'src/core/server';
 import { BASE_API_URL } from '../../common';
 import { IndexPatternAttributes, UI_SETTINGS } from '../../../../../src/plugins/data/server';
 
+export function isBoomError(error: { isBoom?: boolean }): error is Boom {
+  return error.isBoom === true;
+}
+
 /**
  * The number of docs to sample to determine field empty status.
  */
@@ -24,7 +28,7 @@ export interface Field {
   script?: string;
 }
 
-export async function existingFieldsRoute(setup: CoreSetup) {
+export async function existingFieldsRoute(setup: CoreSetup, logger: Logger) {
   const router = setup.http.createRouter();
 
   router.post(
@@ -52,14 +56,17 @@ export async function existingFieldsRoute(setup: CoreSetup) {
           }),
         });
       } catch (e) {
+        logger.info(
+          `Field existence check failed: ${isBoomError(e) ? e.output.payload.message : e.message}`
+        );
         if (e.status === 404) {
-          return res.notFound();
+          return res.notFound({ body: e.message });
         }
-        if (e.isBoom) {
+        if (isBoomError(e)) {
           if (e.output.statusCode === 404) {
-            return res.notFound();
+            return res.notFound({ body: e.output.payload.message });
           }
-          return res.internalError(e.output.message);
+          return res.internalError({ body: e.output.payload.message });
         } else {
           return res.internalError({
             body: Boom.internal(e.message || e.name),
diff --git a/x-pack/plugins/lens/server/routes/index.ts b/x-pack/plugins/lens/server/routes/index.ts
index 8bc04a56e16d5..01018d8cd7fe5 100644
--- a/x-pack/plugins/lens/server/routes/index.ts
+++ b/x-pack/plugins/lens/server/routes/index.ts
@@ -4,13 +4,13 @@
  * you may not use this file except in compliance with the Elastic License.
  */
 
-import { CoreSetup } from 'src/core/server';
+import { CoreSetup, Logger } from 'src/core/server';
 import { existingFieldsRoute } from './existing_fields';
 import { initFieldsRoute } from './field_stats';
 import { initLensUsageRoute } from './telemetry';
 
-export function setupRoutes(setup: CoreSetup) {
-  existingFieldsRoute(setup);
+export function setupRoutes(setup: CoreSetup, logger: Logger) {
+  existingFieldsRoute(setup, logger);
   initFieldsRoute(setup);
   initLensUsageRoute(setup);
 }