Allow interception of http requests from browser http service (#36939)

* Allow interception of http requests from browser http service

* Update documentation and browser http types

* Remove async marker from fetch function

* Fix failing tests

* Attempting to fix kuery_autocomplete test

* Allow halting of http fetches from interception

* Re-use HttpInterceptHaltError

* Expose HttpInterceptor types and update docs

* Only mock calls to capabilities during browser testing

docs/development/core/public/kibana-plugin-public.httpinterceptor.md

@@ -0,0 +1,22 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index) &gt; [kibana-plugin-public](./kibana-plugin-public.md) &gt; [HttpInterceptor](./kibana-plugin-public.httpinterceptor.md)
+
+## HttpInterceptor interface
+
+
+<b>Signature:</b>
+
+```typescript
+export interface HttpInterceptor 
+```
+
+## Methods
+
+|  Method | Description |
+|  --- | --- |
+|  [request(request, controller)](./kibana-plugin-public.httpinterceptor.request.md) |  |
+|  [requestError(httpErrorRequest, controller)](./kibana-plugin-public.httpinterceptor.requesterror.md) |  |
+|  [response(httpResponse, controller)](./kibana-plugin-public.httpinterceptor.response.md) |  |
+|  [responseError(httpErrorResponse, controller)](./kibana-plugin-public.httpinterceptor.responseerror.md) |  |
+

docs/development/core/public/kibana-plugin-public.httpinterceptor.request.md

@@ -0,0 +1,23 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index) &gt; [kibana-plugin-public](./kibana-plugin-public.md) &gt; [HttpInterceptor](./kibana-plugin-public.httpinterceptor.md) &gt; [request](./kibana-plugin-public.httpinterceptor.request.md)
+
+## HttpInterceptor.request() method
+
+<b>Signature:</b>
+
+```typescript
+request?(request: Request, controller: HttpInterceptController): Promise<Request> | Request | void;
+```
+
+## Parameters
+
+|  Parameter | Type | Description |
+|  --- | --- | --- |
+|  request | <code>Request</code> |  |
+|  controller | <code>HttpInterceptController</code> |  |
+
+<b>Returns:</b>
+
+`Promise<Request> | Request | void`
+

docs/development/core/public/kibana-plugin-public.httpinterceptor.requesterror.md

@@ -0,0 +1,23 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index) &gt; [kibana-plugin-public](./kibana-plugin-public.md) &gt; [HttpInterceptor](./kibana-plugin-public.httpinterceptor.md) &gt; [requestError](./kibana-plugin-public.httpinterceptor.requesterror.md)
+
+## HttpInterceptor.requestError() method
+
+<b>Signature:</b>
+
+```typescript
+requestError?(httpErrorRequest: HttpErrorRequest, controller: HttpInterceptController): Promise<Request> | Request | void;
+```
+
+## Parameters
+
+|  Parameter | Type | Description |
+|  --- | --- | --- |
+|  httpErrorRequest | <code>HttpErrorRequest</code> |  |
+|  controller | <code>HttpInterceptController</code> |  |
+
+<b>Returns:</b>
+
+`Promise<Request> | Request | void`
+

docs/development/core/public/kibana-plugin-public.httpinterceptor.response.md

@@ -0,0 +1,23 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index) &gt; [kibana-plugin-public](./kibana-plugin-public.md) &gt; [HttpInterceptor](./kibana-plugin-public.httpinterceptor.md) &gt; [response](./kibana-plugin-public.httpinterceptor.response.md)
+
+## HttpInterceptor.response() method
+
+<b>Signature:</b>
+
+```typescript
+response?(httpResponse: HttpResponse, controller: HttpInterceptController): Promise<HttpResponse> | HttpResponse | void;
+```
+
+## Parameters
+
+|  Parameter | Type | Description |
+|  --- | --- | --- |
+|  httpResponse | <code>HttpResponse</code> |  |
+|  controller | <code>HttpInterceptController</code> |  |
+
+<b>Returns:</b>
+
+`Promise<HttpResponse> | HttpResponse | void`
+

docs/development/core/public/kibana-plugin-public.httpinterceptor.responseerror.md

@@ -0,0 +1,23 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index) &gt; [kibana-plugin-public](./kibana-plugin-public.md) &gt; [HttpInterceptor](./kibana-plugin-public.httpinterceptor.md) &gt; [responseError](./kibana-plugin-public.httpinterceptor.responseerror.md)
+
+## HttpInterceptor.responseError() method
+
+<b>Signature:</b>
+
+```typescript
+responseError?(httpErrorResponse: HttpErrorResponse, controller: HttpInterceptController): Promise<HttpResponse> | HttpResponse | void;
+```
+
+## Parameters
+
+|  Parameter | Type | Description |
+|  --- | --- | --- |
+|  httpErrorResponse | <code>HttpErrorResponse</code> |  |
+|  controller | <code>HttpInterceptController</code> |  |
+
+<b>Returns:</b>
+
+`Promise<HttpResponse> | HttpResponse | void`
+

docs/development/core/public/kibana-plugin-public.httpservicebase.intercept.md

@@ -0,0 +1,22 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index) &gt; [kibana-plugin-public](./kibana-plugin-public.md) &gt; [HttpServiceBase](./kibana-plugin-public.httpservicebase.md) &gt; [intercept](./kibana-plugin-public.httpservicebase.intercept.md)
+
+## HttpServiceBase.intercept() method
+
+<b>Signature:</b>
+
+```typescript
+intercept(interceptor: HttpInterceptor): () => void;
+```
+
+## Parameters
+
+|  Parameter | Type | Description |
+|  --- | --- | --- |
+|  interceptor | <code>HttpInterceptor</code> |  |
+
+<b>Returns:</b>
+
+`() => void`
+

docs/development/core/public/kibana-plugin-public.httpservicebase.md

@@ -31,7 +31,9 @@ export interface HttpServiceBase
 |  [addLoadingCount(count$)](./kibana-plugin-public.httpservicebase.addloadingcount.md) |  |
 |  [getBasePath()](./kibana-plugin-public.httpservicebase.getbasepath.md) |  |
 |  [getLoadingCount$()](./kibana-plugin-public.httpservicebase.getloadingcount$.md) |  |
+|  [intercept(interceptor)](./kibana-plugin-public.httpservicebase.intercept.md) |  |
 |  [prependBasePath(path)](./kibana-plugin-public.httpservicebase.prependbasepath.md) |  |
+|  [removeAllInterceptors()](./kibana-plugin-public.httpservicebase.removeallinterceptors.md) |  |
 |  [removeBasePath(path)](./kibana-plugin-public.httpservicebase.removebasepath.md) |  |
 |  [stop()](./kibana-plugin-public.httpservicebase.stop.md) |  |
 

docs/development/core/public/kibana-plugin-public.httpservicebase.removeallinterceptors.md

@@ -0,0 +1,15 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index) &gt; [kibana-plugin-public](./kibana-plugin-public.md) &gt; [HttpServiceBase](./kibana-plugin-public.httpservicebase.md) &gt; [removeAllInterceptors](./kibana-plugin-public.httpservicebase.removeallinterceptors.md)
+
+## HttpServiceBase.removeAllInterceptors() method
+
+<b>Signature:</b>
+
+```typescript
+removeAllInterceptors(): void;
+```
+<b>Returns:</b>
+
+`void`
+

docs/development/core/public/kibana-plugin-public.md

@@ -33,6 +33,7 @@ The plugin integrates with the core system via lifecycle events: `setup`<!-- -->
 |  [ErrorToastOptions](./kibana-plugin-public.errortoastoptions.md) |  |
 |  [FatalErrorInfo](./kibana-plugin-public.fatalerrorinfo.md) | Represents the <code>message</code> and <code>stack</code> of a fatal Error |
 |  [FatalErrorsSetup](./kibana-plugin-public.fatalerrorssetup.md) | FatalErrors stop the Kibana Public Core and displays a fatal error screen with details about the Kibana build and the error. |
+|  [HttpInterceptor](./kibana-plugin-public.httpinterceptor.md) |  |
 |  [HttpServiceBase](./kibana-plugin-public.httpservicebase.md) |  |
 |  [I18nSetup](./kibana-plugin-public.i18nsetup.md) | I18nSetup.Context is required by any localizable React component from @<!-- -->kbn/i18n and @<!-- -->elastic/eui packages and is supposed to be used as the topmost component for any i18n-compatible React tree. |
 |  [LegacyNavLink](./kibana-plugin-public.legacynavlink.md) |  |

src/core/public/http/http_intercept_controller.ts

@@ -0,0 +1,30 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+export class HttpInterceptController {
+  private _halted = false;
+
+  get halted() {
+    return this._halted;
+  }
+
+  halt() {
+    this._halted = true;
+  }
+}

src/core/public/http/http_intercept_halt_error.ts

@@ -0,0 +1,30 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+export class HttpInterceptHaltError extends Error {
+  constructor() {
+    super('HTTP Intercept Halt');
+
+    // captureStackTrace is only available in the V8 engine, so any browser using
+    // a different JS engine won't have access to this method.
+    if (Error.captureStackTrace) {
+      Error.captureStackTrace(this, HttpInterceptHaltError);
+    }
+  }
+}

src/core/public/http/http_service.mock.ts

@@ -35,6 +35,8 @@ const createServiceMock = () => ({
   addLoadingCount: jest.fn(),
   getLoadingCount$: jest.fn(),
   stop: jest.fn(),
+  intercept: jest.fn(),
+  removeAllInterceptors: jest.fn(),
 });
 
 const createSetupContractMock = (): jest.Mocked<HttpSetup> => createServiceMock();

src/core/public/http/http_service.test.ts

@@ -126,7 +126,7 @@ describe('http requests', () => {
     await http.fetch('/my/path', { headers: { 'Content-Type': 'CustomContentType' } });
 
     expect(fetchMock.lastOptions()!.headers).toMatchObject({
-      'Content-Type': 'CustomContentType',
+      'content-type': 'CustomContentType',
     });
   });
 
@@ -148,9 +148,9 @@ describe('http requests', () => {
     });
 
     expect(fetchMock.lastOptions()!.headers).toEqual({
-      'Content-Type': 'application/json',
+      'content-type': 'application/json',
       'kbn-version': 'kibanaVersion',
-      myHeader: 'foo',
+      myheader: 'foo',
     });
   });
 
@@ -188,11 +188,13 @@ describe('http requests', () => {
     fetchMock.get('*', {});
     await http.fetch('/my/path');
 
-    expect(fetchMock.lastOptions()!).toMatchObject({
+    const lastCall = fetchMock.lastCall();
+
+    expect(lastCall!.request.credentials).toBe('same-origin');
+    expect(lastCall![1]).toMatchObject({
       method: 'GET',
-      credentials: 'same-origin',
       headers: {
-        'Content-Type': 'application/json',
+        'content-type': 'application/json',
         'kbn-version': 'kibanaVersion',
       },
     });
@@ -313,6 +315,258 @@ describe('http requests', () => {
   });
 });
 
+describe('interception', () => {
+  const { http } = setup();
+
+  beforeEach(() => {
+    fetchMock.get('*', { foo: 'bar' });
+  });
+
+  afterEach(() => {
+    fetchMock.restore();
+    http.removeAllInterceptors();
+  });
+
+  it('should make request and receive response', async () => {
+    http.intercept({});
+
+    const body = await http.fetch('/my/path');
+
+    expect(fetchMock.called()).toBe(true);
+    expect(body).toEqual({ foo: 'bar' });
+  });
+
+  it('should be able to manipulate request instance', async () => {
+    http.intercept({
+      request(request) {
+        request.headers.set('Content-Type', 'CustomContentType');
+      },
+    });
+    http.intercept({
+      request(request) {
+        return new Request('/my/route', request);
+      },
+    });
+
+    const body = await http.fetch('/my/path');
+
+    expect(fetchMock.called()).toBe(true);
+    expect(body).toEqual({ foo: 'bar' });
+    expect(fetchMock.lastOptions()!.headers).toMatchObject({
+      'content-type': 'CustomContentType',
+    });
+    expect(fetchMock.lastUrl()).toBe('/my/route');
+  });
+
+  it('should call interceptors in correct order', async () => {
+    const order: string[] = [];
+
+    http.intercept({
+      request() {
+        order.push('Request 1');
+      },
+      response() {
+        order.push('Response 1');
+      },
+    });
+    http.intercept({
+      request() {
+        order.push('Request 2');
+      },
+      response() {
+        order.push('Response 2');
+      },
+    });
+    http.intercept({
+      request() {
+        order.push('Request 3');
+      },
+      response() {
+        order.push('Response 3');
+      },
+    });
+
+    const body = await http.fetch('/my/path');
+
+    expect(fetchMock.called()).toBe(true);
+    expect(body).toEqual({ foo: 'bar' });
+    expect(order).toEqual([
+      'Request 3',
+      'Request 2',
+      'Request 1',
+      'Response 1',
+      'Response 2',
+      'Response 3',
+    ]);
+  });
+
+  it('should skip remaining interceptors when controller halts during request', async () => {
+    const order: string[] = [];
+
+    http.intercept({
+      request() {
+        order.push('Request 1');
+      },
+      response() {
+        order.push('Response 1');
+      },
+    });
+    http.intercept({
+      request(request, controller) {
+        controller.halt();
+        order.push('Request 2');
+      },
+      response() {
+        order.push('Response 2');
+      },
+    });
+    http.intercept({
+      request() {
+        order.push('Request 3');
+      },
+      response() {
+        order.push('Response 3');
+      },
+    });
+
+    await expect(http.fetch('/my/wat')).rejects.toThrow(/HTTP Intercept Halt/);
+    expect(fetchMock.called()).toBe(false);
+    expect(order).toEqual(['Request 3', 'Request 2']);
+  });
+
+  it('should skip remaining interceptors when controller halts during response', async () => {
+    const order: string[] = [];
+
+    http.intercept({
+      request() {
+        order.push('Request 1');
+      },
+      response(response, controller) {
+        controller.halt();
+        order.push('Response 1');
+      },
+    });
+    http.intercept({
+      request() {
+        order.push('Request 2');
+      },
+      response() {
+        order.push('Response 2');
+      },
+    });
+    http.intercept({
+      request() {
+        order.push('Request 3');
+      },
+      response() {
+        order.push('Response 3');
+      },
+    });
+
+    await expect(http.fetch('/my/wat')).rejects.toThrow(/HTTP Intercept Halt/);
+    expect(fetchMock.called()).toBe(true);
+    expect(order).toEqual(['Request 3', 'Request 2', 'Request 1', 'Response 1']);
+  });
+
+  it('should not fetch if exception occurs during request interception', async () => {
+    const order: string[] = [];
+
+    http.intercept({
+      request() {
+        order.push('Request 1');
+      },
+      requestError() {
+        order.push('RequestError 1');
+      },
+      response() {
+        order.push('Response 1');
+      },
+      responseError() {
+        order.push('ResponseError 1');
+      },
+    });
+    http.intercept({
+      request() {
+        order.push('Request 2');
+        throw new Error('Interception Error');
+      },
+      response() {
+        order.push('Response 2');
+      },
+      responseError() {
+        order.push('ResponseError 2');
+      },
+    });
+    http.intercept({
+      request() {
+        order.push('Request 3');
+      },
+      response() {
+        order.push('Response 3');
+      },
+      responseError() {
+        order.push('ResponseError 3');
+      },
+    });
+
+    await expect(http.fetch('/my/wat')).rejects.toThrow(/Interception Error/);
+    expect(fetchMock.called()).toBe(false);
+    expect(order).toEqual([
+      'Request 3',
+      'Request 2',
+      'RequestError 1',
+      'ResponseError 1',
+      'ResponseError 2',
+      'ResponseError 3',
+    ]);
+  });
+
+  it('should succeed if request throws but caught by interceptor', async () => {
+    const order: string[] = [];
+
+    http.intercept({
+      request() {
+        order.push('Request 1');
+      },
+      requestError({ request }) {
+        order.push('RequestError 1');
+        return new Request('/my/route', request);
+      },
+      response() {
+        order.push('Response 1');
+      },
+    });
+    http.intercept({
+      request() {
+        order.push('Request 2');
+        throw new Error('Interception Error');
+      },
+      response() {
+        order.push('Response 2');
+      },
+    });
+    http.intercept({
+      request() {
+        order.push('Request 3');
+      },
+      response() {
+        order.push('Response 3');
+      },
+    });
+
+    await expect(http.fetch('/my/route')).resolves.toEqual({ foo: 'bar' });
+    expect(fetchMock.called()).toBe(true);
+    expect(order).toEqual([
+      'Request 3',
+      'Request 2',
+      'RequestError 1',
+      'Response 1',
+      'Response 2',
+      'Response 3',
+    ]);
+  });
+});
+
 describe('addLoadingCount()', () => {
   it('subscribes to passed in sources, unsubscribes on stop', () => {
     const { httpService, http } = setup();

src/core/public/http/http_setup.ts

@@ -32,8 +32,10 @@ import { format } from 'url';
 import { InjectedMetadataSetup } from '../injected_metadata';
 import { FatalErrorsSetup } from '../fatal_errors';
 import { modifyUrl } from '../utils';
-import { HttpBody, HttpFetchOptions, HttpServiceBase } from './types';
+import { HttpFetchOptions, HttpServiceBase, HttpInterceptor, HttpResponse } from './types';
+import { HttpInterceptController } from './http_intercept_controller';
 import { HttpFetchError } from './http_fetch_error';
+import { HttpInterceptHaltError } from './http_intercept_halt_error';
 
 const JSON_CONTENT = /^(application\/(json|x-javascript)|text\/(x-)?javascript|x-json)(;.*)?$/;
 const NDJSON_CONTENT = /^(application\/ndjson)(;.*)?$/;
@@ -44,9 +46,20 @@ export const setup = (
 ): HttpServiceBase => {
   const loadingCount$ = new BehaviorSubject(0);
   const stop$ = new Subject();
+  const interceptors = new Set<HttpInterceptor>();
   const kibanaVersion = injectedMetadata.getKibanaVersion();
   const basePath = injectedMetadata.getBasePath() || '';
 
+  function intercept(interceptor: HttpInterceptor) {
+    interceptors.add(interceptor);
+
+    return () => interceptors.delete(interceptor);
+  }
+
+  function removeAllInterceptors() {
+    interceptors.clear();
+  }
+
   function prependBasePath(path: string): string {
     return modifyUrl(path, parts => {
       if (!parts.hostname && parts.pathname && parts.pathname.startsWith('/')) {
@@ -55,7 +68,7 @@ export const setup = (
     });
   }
 
-  async function fetch(path: string, options?: HttpFetchOptions): Promise<HttpBody> {
+  function createRequest(path: string, options?: HttpFetchOptions) {
     const { query, prependBasePath: shouldPrependBasePath, ...fetchOptions } = merge(
       {
         method: 'GET',
@@ -82,11 +95,116 @@ export const setup = (
       delete fetchOptions.headers['Content-Type'];
     }
 
+    return new Request(url, fetchOptions);
+  }
+
+  // Request/response interceptors are called in opposite orders.
+  // Request hooks start from the newest interceptor and end with the oldest.
+  function interceptRequest(
+    request: Request,
+    controller: HttpInterceptController
+  ): Promise<Request> {
+    let next = request;
+
+    return [...interceptors].reduceRight(
+      (promise, interceptor) =>
+        promise.then(
+          async (current: Request) => {
+            if (controller.halted) {
+              throw new HttpInterceptHaltError();
+            }
+
+            if (!interceptor.request) {
+              return current;
+            }
+
+            next = (await interceptor.request(current, controller)) || current;
+
+            return next;
+          },
+          async error => {
+            if (error instanceof HttpInterceptHaltError) {
+              throw error;
+            } else if (controller.halted) {
+              throw new HttpInterceptHaltError();
+            }
+
+            if (!interceptor.requestError) {
+              throw error;
+            }
+
+            const nextRequest = await interceptor.requestError(
+              { error, request: next },
+              controller
+            );
+
+            if (!nextRequest) {
+              throw error;
+            }
+
+            next = nextRequest;
+            return next;
+          }
+        ),
+      Promise.resolve(request)
+    );
+  }
+
+  // Response hooks start from the oldest interceptor and end with the newest.
+  async function interceptResponse(
+    responsePromise: Promise<HttpResponse>,
+    controller: HttpInterceptController
+  ) {
+    let current: HttpResponse;
+
+    const finalHttpResponse = await [...interceptors].reduce(
+      (promise, interceptor) =>
+        promise.then(
+          async httpResponse => {
+            if (controller.halted) {
+              throw new HttpInterceptHaltError();
+            }
+
+            if (!interceptor.response) {
+              return httpResponse;
+            }
+
+            current = (await interceptor.response(httpResponse, controller)) || httpResponse;
+
+            return current;
+          },
+          async error => {
+            if (error instanceof HttpInterceptHaltError) {
+              throw error;
+            } else if (controller.halted) {
+              throw new HttpInterceptHaltError();
+            }
+
+            if (!interceptor.responseError) {
+              throw error;
+            }
+
+            const next = await interceptor.responseError({ ...current, error }, controller);
+
+            if (!next) {
+              throw error;
+            }
+
+            return next;
+          }
+        ),
+      responsePromise
+    );
+
+    return finalHttpResponse.body;
+  }
+
+  async function fetcher(request: Request): Promise<HttpResponse> {
     let response;
     let body = null;
 
     try {
-      response = await window.fetch(url, fetchOptions as RequestInit);
+      response = await window.fetch(request);
     } catch (err) {
       throw new HttpFetchError(err.message);
     }
@@ -115,7 +233,17 @@ export const setup = (
       throw new HttpFetchError(response.statusText, response, body);
     }
 
-    return body;
+    return { response, body, request };
+  }
+
+  function fetch(path: string, options: HttpFetchOptions = {}) {
+    const controller = new HttpInterceptController();
+    const initialRequest = createRequest(path, options);
+
+    return interceptResponse(
+      interceptRequest(initialRequest, controller).then(fetcher),
+      controller
+    );
   }
 
   function shorthand(method: string) {
@@ -189,6 +317,8 @@ export const setup = (
     getBasePath,
     prependBasePath,
     removeBasePath,
+    intercept,
+    removeAllInterceptors,
     fetch,
     delete: shorthand('DELETE'),
     get: shorthand('GET'),

src/core/public/http/index.ts

@@ -19,4 +19,6 @@
 
 export { HttpService } from './http_service';
 export { HttpFetchError } from './http_fetch_error';
-export { HttpServiceBase, HttpSetup, HttpStart } from './types';
+export { HttpInterceptHaltError } from './http_intercept_halt_error';
+export { HttpInterceptController } from './http_intercept_controller';
+export * from './types';

src/core/public/http/types.ts

@@ -20,6 +20,8 @@
 import { Observable } from 'rxjs';
 import { InjectedMetadataSetup } from '../injected_metadata';
 import { FatalErrorsSetup } from '../fatal_errors';
+import { HttpInterceptController } from './http_intercept_controller';
+import { HttpFetchError } from './http_fetch_error';
 
 /** @public */
 export interface HttpServiceBase {
@@ -27,6 +29,8 @@ export interface HttpServiceBase {
   getBasePath(): string;
   prependBasePath(path: string): string;
   removeBasePath(path: string): string;
+  intercept(interceptor: HttpInterceptor): () => void;
+  removeAllInterceptors(): void;
   fetch: HttpHandler;
   delete: HttpHandler;
   get: HttpHandler;
@@ -80,4 +84,38 @@ export interface HttpFetchOptions extends HttpRequestInit {
 /** @public */
 export type HttpHandler = (path: string, options?: HttpFetchOptions) => Promise<HttpBody>;
 /** @public */
-export type HttpBody = BodyInit | null;
+export type HttpBody = BodyInit | null | any;
+/** @public */
+export interface HttpResponse {
+  request: Request;
+  response?: Response;
+  body?: HttpBody;
+}
+/** @public */
+export interface HttpErrorResponse extends HttpResponse {
+  error: Error | HttpFetchError;
+}
+/** @public */
+export interface HttpErrorRequest {
+  request?: Request;
+  error: Error;
+}
+/** @public */
+export interface HttpInterceptor {
+  request?(
+    request: Request,
+    controller: HttpInterceptController
+  ): Promise<Request> | Request | void;
+  requestError?(
+    httpErrorRequest: HttpErrorRequest,
+    controller: HttpInterceptController
+  ): Promise<Request> | Request | void;
+  response?(
+    httpResponse: HttpResponse,
+    controller: HttpInterceptController
+  ): Promise<HttpResponse> | HttpResponse | void;
+  responseError?(
+    httpErrorResponse: HttpErrorResponse,
+    controller: HttpInterceptController
+  ): Promise<HttpResponse> | HttpResponse | void;
+}

src/core/public/index.ts

@@ -45,7 +45,7 @@ import {
   ChromeStart,
 } from './chrome';
 import { FatalErrorsSetup, FatalErrorInfo } from './fatal_errors';
-import { HttpServiceBase, HttpSetup, HttpStart } from './http';
+import { HttpServiceBase, HttpSetup, HttpStart, HttpInterceptor } from './http';
 import { I18nSetup, I18nStart } from './i18n';
 import { InjectedMetadataSetup, InjectedMetadataStart, LegacyNavLink } from './injected_metadata';
 import {
@@ -129,6 +129,7 @@ export {
   HttpServiceBase,
   HttpSetup,
   HttpStart,
+  HttpInterceptor,
   ErrorToastOptions,
   FatalErrorsSetup,
   FatalErrorInfo,

src/core/public/public.api.md

@@ -174,6 +174,26 @@ export interface FatalErrorsSetup {
     get$: () => Rx.Observable<FatalErrorInfo>;
 }
 
+// @public (undocumented)
+export interface HttpInterceptor {
+    // Warning: (ae-forgotten-export) The symbol "HttpInterceptController" needs to be exported by the entry point index.d.ts
+    // 
+    // (undocumented)
+    request?(request: Request, controller: HttpInterceptController): Promise<Request> | Request | void;
+    // Warning: (ae-forgotten-export) The symbol "HttpErrorRequest" needs to be exported by the entry point index.d.ts
+    // 
+    // (undocumented)
+    requestError?(httpErrorRequest: HttpErrorRequest, controller: HttpInterceptController): Promise<Request> | Request | void;
+    // Warning: (ae-forgotten-export) The symbol "HttpResponse" needs to be exported by the entry point index.d.ts
+    // 
+    // (undocumented)
+    response?(httpResponse: HttpResponse, controller: HttpInterceptController): Promise<HttpResponse> | HttpResponse | void;
+    // Warning: (ae-forgotten-export) The symbol "HttpErrorResponse" needs to be exported by the entry point index.d.ts
+    // 
+    // (undocumented)
+    responseError?(httpErrorResponse: HttpErrorResponse, controller: HttpInterceptController): Promise<HttpResponse> | HttpResponse | void;
+}
+
 // @public (undocumented)
 export interface HttpServiceBase {
     // (undocumented)
@@ -193,6 +213,8 @@ export interface HttpServiceBase {
     // (undocumented)
     head: HttpHandler;
     // (undocumented)
+    intercept(interceptor: HttpInterceptor): () => void;
+    // (undocumented)
     options: HttpHandler;
     // (undocumented)
     patch: HttpHandler;
@@ -203,6 +225,8 @@ export interface HttpServiceBase {
     // (undocumented)
     put: HttpHandler;
     // (undocumented)
+    removeAllInterceptors(): void;
+    // (undocumented)
     removeBasePath(path: string): string;
     // (undocumented)
     stop(): void;

src/core/public/ui_settings/__snapshots__/ui_settings_api.test.ts.snap

@@ -5,11 +5,9 @@ Array [
   Array [
     "/foo/bar/api/kibana/settings",
     Object {
-      "body": "{\\"changes\\":{\\"foo\\":\\"bar\\"}}",
-      "credentials": "same-origin",
       "headers": Object {
-        "Content-Type": "application/json",
         "accept": "application/json",
+        "content-type": "application/json",
         "kbn-version": "kibanaVersion",
       },
       "method": "POST",
@@ -18,11 +16,9 @@ Array [
   Array [
     "/foo/bar/api/kibana/settings",
     Object {
-      "body": "{\\"changes\\":{\\"bar\\":\\"box\\"}}",
-      "credentials": "same-origin",
       "headers": Object {
-        "Content-Type": "application/json",
         "accept": "application/json",
+        "content-type": "application/json",
         "kbn-version": "kibanaVersion",
       },
       "method": "POST",
@@ -36,11 +32,9 @@ Array [
   Array [
     "/foo/bar/api/kibana/settings",
     Object {
-      "body": "{\\"changes\\":{\\"foo\\":\\"a\\"}}",
-      "credentials": "same-origin",
       "headers": Object {
-        "Content-Type": "application/json",
         "accept": "application/json",
+        "content-type": "application/json",
         "kbn-version": "kibanaVersion",
       },
       "method": "POST",
@@ -49,11 +43,9 @@ Array [
   Array [
     "/foo/bar/api/kibana/settings",
     Object {
-      "body": "{\\"changes\\":{\\"foo\\":\\"d\\"}}",
-      "credentials": "same-origin",
       "headers": Object {
-        "Content-Type": "application/json",
         "accept": "application/json",
+        "content-type": "application/json",
         "kbn-version": "kibanaVersion",
       },
       "method": "POST",
@@ -67,11 +59,9 @@ Array [
   Array [
     "/foo/bar/api/kibana/settings",
     Object {
-      "body": "{\\"changes\\":{\\"foo\\":\\"bar\\"}}",
-      "credentials": "same-origin",
       "headers": Object {
-        "Content-Type": "application/json",
         "accept": "application/json",
+        "content-type": "application/json",
         "kbn-version": "kibanaVersion",
       },
       "method": "POST",
@@ -80,29 +70,9 @@ Array [
   Array [
     "/foo/bar/api/kibana/settings",
     Object {
-      "body": "{\\"changes\\":{\\"box\\":\\"bar\\"}}",
-      "credentials": "same-origin",
       "headers": Object {
-        "Content-Type": "application/json",
-        "accept": "application/json",
-        "kbn-version": "kibanaVersion",
-      },
-      "method": "POST",
-    },
-  ],
-]
-`;
-
-exports[`#batchSet buffers changes while first request is in progress, sends buffered changes after first request completes: initial, only one request 1`] = `
-Array [
-  Array [
-    "/foo/bar/api/kibana/settings",
-    Object {
-      "body": "{\\"changes\\":{\\"foo\\":\\"bar\\"}}",
-      "credentials": "same-origin",
-      "headers": Object {
-        "Content-Type": "application/json",
         "accept": "application/json",
+        "content-type": "application/json",
         "kbn-version": "kibanaVersion",
       },
       "method": "POST",
@@ -134,16 +104,14 @@ exports[`#batchSet rejects on 404 response 1`] = `"Request failed with status co
 
 exports[`#batchSet rejects on 500 1`] = `"Request failed with status code: 500"`;
 
-exports[`#batchSet sends a single change immediately: synchronous fetch 1`] = `
+exports[`#batchSet sends a single change immediately: single change 1`] = `
 Array [
   Array [
     "/foo/bar/api/kibana/settings",
     Object {
-      "body": "{\\"changes\\":{\\"foo\\":\\"bar\\"}}",
-      "credentials": "same-origin",
       "headers": Object {
-        "Content-Type": "application/json",
         "accept": "application/json",
+        "content-type": "application/json",
         "kbn-version": "kibanaVersion",
       },
       "method": "POST",

src/core/public/ui_settings/__snapshots__/ui_settings_service.test.ts.snap

@@ -26,11 +26,13 @@ exports[`#setup constructs UiSettingsClient and UiSettingsApi: UiSettingsApi arg
         "getBasePath": [MockFunction],
         "getLoadingCount$": [MockFunction],
         "head": [MockFunction],
+        "intercept": [MockFunction],
         "options": [MockFunction],
         "patch": [MockFunction],
         "post": [MockFunction],
         "prependBasePath": [MockFunction],
         "put": [MockFunction],
+        "removeAllInterceptors": [MockFunction],
         "removeBasePath": [MockFunction],
         "stop": [MockFunction],
       },

src/core/public/ui_settings/ui_settings_api.test.ts

@@ -57,14 +57,14 @@ afterEach(() => {
 });
 
 describe('#batchSet', () => {
-  it('sends a single change immediately', () => {
+  it('sends a single change immediately', async () => {
     fetchMock.mock('*', {
       body: { settings: {} },
     });
 
     const { uiSettingsApi } = setup();
-    uiSettingsApi.batchSet('foo', 'bar');
-    expect(fetchMock.calls()).toMatchSnapshot('synchronous fetch');
+    await uiSettingsApi.batchSet('foo', 'bar');
+    expect(fetchMock.calls()).toMatchSnapshot('single change');
   });
 
   it('buffers changes while first request is in progress, sends buffered changes after first request completes', async () => {
@@ -77,7 +77,7 @@ describe('#batchSet', () => {
     uiSettingsApi.batchSet('foo', 'bar');
     const finalPromise = uiSettingsApi.batchSet('box', 'bar');
 
-    expect(fetchMock.calls()).toMatchSnapshot('initial, only one request');
+    expect(uiSettingsApi.hasPendingChanges()).toBe(true);
     await finalPromise;
     expect(fetchMock.calls()).toMatchSnapshot('final, includes both requests');
   });

src/core/public/ui_settings/ui_settings_api.ts

@@ -93,6 +93,13 @@ export class UiSettingsApi {
     this.loadingCount$.complete();
   }
 
+  /**
+   * Report back if there are pending changes waiting to be sent.
+   */
+  public hasPendingChanges() {
+    return !!(this.pendingChanges && this.sendInProgress);
+  }
+
   /**
    * If there are changes that need to be sent to the server and there is not already a
    * request in progress, this method will start a request sending those changes. Once

src/legacy/core_plugins/tests_bundle/tests_entry_template.js

@@ -35,7 +35,7 @@ import 'custom-event-polyfill';
 import 'whatwg-fetch';
 import 'abortcontroller-polyfill';
 import 'childnode-remove-polyfill';
-import sinon from 'sinon';
+import fetchMock from 'fetch-mock/es5/client';
 
 import { CoreSystem } from '__kibanaCore__';
 
@@ -59,22 +59,12 @@ const uiCapabilities = {
   },
 };
 
-// Stub fetch for CoreSystem calls.
-const fetchStub = sinon.stub(window, 'fetch');
-fetchStub.callsFake((url, options) => {
-  if (url !== '/api/capabilities') {
-    console.warn('Stubbed window.fetch does not support this request.');
-    return Promise.resolve(new window.Response('Resource not found', { status: 404 }));
-  }
-
-  return Promise.resolve(
-    new window.Response(
-      JSON.stringify({ capabilities: uiCapabilities })),
-      {
-        status: 200,
-        headers: { 'Content-Type': 'application/json' }
-      }
-    );
+// Mock fetch for CoreSystem calls.
+fetchMock.config.fallbackToNetwork = true;
+fetchMock.post(/\\/api\\/capabilities/, {
+  status: 200,
+  body: JSON.stringify({ capabilities: uiCapabilities }),
+  headers: { 'Content-Type': 'application/json' },
 });
 
 // render the core system in a child of the body as the default children of the body

src/legacy/ui/public/kfetch/kfetch.test.ts

@@ -46,7 +46,7 @@ describe('kfetch', () => {
     fetchMock.get('*', {});
     await kfetch({ pathname: '/my/path', headers: { 'Content-Type': 'CustomContentType' } });
     expect(fetchMock.lastOptions()!.headers).toMatchObject({
-      'Content-Type': 'CustomContentType',
+      'content-type': 'CustomContentType',
     });
   });
 
@@ -64,9 +64,9 @@ describe('kfetch', () => {
     });
 
     expect(fetchMock.lastOptions()!.headers).toEqual({
-      'Content-Type': 'application/json',
+      'content-type': 'application/json',
       'kbn-version': 'kibanaVersion',
-      myHeader: 'foo',
+      myheader: 'foo',
     });
   });
 
@@ -92,11 +92,11 @@ describe('kfetch', () => {
     fetchMock.get('*', {});
     await kfetch({ pathname: '/my/path' });
 
+    expect(fetchMock.lastCall()!.request.credentials).toBe('same-origin');
     expect(fetchMock.lastOptions()!).toMatchObject({
       method: 'GET',
-      credentials: 'same-origin',
       headers: {
-        'Content-Type': 'application/json',
+        'content-type': 'application/json',
         'kbn-version': 'kibanaVersion',
       },
     });
@@ -359,7 +359,7 @@ describe('kfetch', () => {
       addInterceptor({
         request: config => ({
           ...config,
-          addedByRequestInterceptor: true,
+          pathname: '/my/intercepted-route',
         }),
         response: res => ({
           ...res,
@@ -371,8 +371,8 @@ describe('kfetch', () => {
     });
 
     it('should modify request', () => {
+      expect(fetchMock.lastUrl()).toContain('/my/intercepted-route');
       expect(fetchMock.lastOptions()!).toMatchObject({
-        addedByRequestInterceptor: true,
         method: 'GET',
       });
     });
@@ -393,7 +393,7 @@ describe('kfetch', () => {
         request: config =>
           Promise.resolve({
             ...config,
-            addedByRequestInterceptor: true,
+            pathname: '/my/intercepted-route',
           }),
         response: res =>
           Promise.resolve({
@@ -406,8 +406,8 @@ describe('kfetch', () => {
     });
 
     it('should modify request', () => {
+      expect(fetchMock.lastUrl()).toContain('/my/intercepted-route');
       expect(fetchMock.lastOptions()!).toMatchObject({
-        addedByRequestInterceptor: true,
         method: 'GET',
       });
     });

x-pack/plugins/kuery_autocomplete/public/autocomplete_providers/__tests__/value.js

@@ -72,13 +72,13 @@ describe('Kuery value suggestions', function () {
     const suggestions = await getSuggestions({ fieldName, prefix, suffix });
 
     const lastCall = fetchMock.lastCall(fetchUrlMatcher, 'POST');
-    expect(lastCall[0]).to.eql('/api/kibana/suggestions/values/logstash-*');
+
+    expect(lastCall.request._bodyInit, '{"query":"","field":"machine.os.raw","boolFilter":[]}');
+    expect(lastCall[0]).to.match(/\/api\/kibana\/suggestions\/values\/logstash-\*/);
     expect(lastCall[1]).to.eql({
       method: 'POST',
-      body: '{"query":"","field":"machine.os.raw","boolFilter":[]}',
-      credentials: 'same-origin',
       headers: {
-        'Content-Type': 'application/json',
+        'content-type': 'application/json',
         'kbn-version': '1.2.3',
       },
     });