Token should retry after refresh failure to avoid eventual client disconnection from the editing session

packages/ckeditor5-cloud-services/src/cloudservicesconfig.ts

@@ -88,6 +88,9 @@ export interface CloudServicesConfig {
 	 * 	} )
 	 * ```
 	 *
+	 * If the request to the token endpoint fails, the editor will call the token request function every 5 seconds in attempt
+	 * to refresh the token.
+	 *
 	 * You can find more information about token endpoints in the
 	 * {@glink @cs guides/easy-image/quick-start#create-token-endpoint Cloud Services - Quick start}
 	 * and {@glink @cs developer-resources/security/token-endpoint Cloud Services - Token endpoint} documentation.

packages/ckeditor5-cloud-services/src/token/token.ts

@@ -9,15 +9,17 @@
 
 /* globals XMLHttpRequest, setTimeout, clearTimeout, atob */
 
-import { ObservableMixin, CKEditorError } from 'ckeditor5/src/utils.js';
+import { ObservableMixin, CKEditorError, logWarning } from 'ckeditor5/src/utils.js';
 import type { TokenUrl } from '../cloudservicesconfig.js';
 
 const DEFAULT_OPTIONS = { autoRefresh: true };
-const DEFAULT_TOKEN_REFRESH_TIMEOUT_TIME = 3600000;
+const DEFAULT_TOKEN_REFRESH_TIMEOUT_TIME = 3600000; // 1 hour
+const TOKEN_FAILED_REFRESH_TIMEOUT_TIME = 5000; // 5 seconds
 
 /**
- * Class representing the token used for communication with CKEditor Cloud Services.
- * Value of the token is retrieving from the specified URL and is refreshed every 1 hour by default.
+ * The class representing the token used for communication with CKEditor Cloud Services.
+ * The value of the token is retrieved from the specified URL and refreshed every 1 hour by default.
+ * If the token retrieval fails, the token will automatically retry in 5 seconds intervals.
  */
 export default class Token extends /* #__PURE__ */ ObservableMixin() {
 	/**
@@ -36,8 +38,14 @@ export default class Token extends /* #__PURE__ */ ObservableMixin() {
 	 */
 	private _refresh: () => Promise<string>;
 
+	/**
+	 * Cached token options.
+	 */
 	private _options: { initValue?: string; autoRefresh: boolean };
 
+	/**
+	 * `setTimeout()` id for a token refresh when {@link module:cloud-services/token/token~TokenOptions auto refresh} is enabled.
+	 */
 	private _tokenRefreshTimeout?: ReturnType<typeof setTimeout>;
 
 	/**
@@ -99,19 +107,55 @@ export default class Token extends /* #__PURE__ */ ObservableMixin() {
 	}
 
 	/**
-	 * Refresh token method. Useful in a method form as it can be override in tests.
+	 * Refresh token method. Useful in a method form as it can be overridden in tests.
+	 *
+	 * This method will be invoked periodically based on the token expiry date after first call to keep the token up-to-date
+	 * (requires {@link module:cloud-services/token/token~TokenOptions auto refresh option} to be set).
+	 *
+	 * If the token refresh fails, the method will retry in 5 seconds intervals until success or the token gets
+	 * {@link #destroy destroyed}.
 	 */
 	public refreshToken(): Promise<InitializedToken> {
+		const autoRefresh = this._options.autoRefresh;
+
 		return this._refresh()
 			.then( value => {
 				this._validateTokenValue( value );
 				this.set( 'value', value );
 
-				if ( this._options.autoRefresh ) {
+				if ( autoRefresh ) {
 					this._registerRefreshTokenTimeout();
 				}
 
 				return this as InitializedToken;
+			} )
+			.catch( err => {
+				/**
+				 * You will see this warning when the CKEditor {@link module:cloud-services/token/token~Token token} could not be refreshed.
+				 * This may be a result of a network error, a token endpoint (server) error, or an invalid
+				 * {@link module:cloud-services/cloudservicesconfig~CloudServicesConfig#tokenUrl token URL configuration}.
+				 *
+				 * If this warning repeats, please make sure that the configuration is correct and that the token
+				 * endpoint is up and running. {@link module:cloud-services/cloudservicesconfig~CloudServicesConfig#tokenUrl Learn more}
+				 * about token configuration.
+				 *
+				 * **Note:** If the token's {@link module:cloud-services/token/token~TokenOptions auto refresh option} is enabled,
+				 * attempts to refresh will be made until success or token's
+				 * {@link module:cloud-services/token/token~Token#destroy destruction}.
+				 *
+				 * @error token-refresh-failed
+				 * @param autoRefresh Whether the token will keep auto refreshing.
+				 */
+				logWarning( 'token-refresh-failed', { autoRefresh } );
+
+				// If the refresh failed, keep trying to refresh the token. Failing to do so will eventually
+				// lead to the disconnection from the RTC service and the editing session (and potential data loss
+				// if the user keeps editing).
+				if ( autoRefresh ) {
+					this._registerRefreshTokenTimeout( TOKEN_FAILED_REFRESH_TIMEOUT_TIME );
+				}
+
+				throw err;
 			} );
 	}
 
@@ -151,8 +195,8 @@ export default class Token extends /* #__PURE__ */ ObservableMixin() {
 	/**
 	 * Registers a refresh token timeout for the time taken from token.
 	 */
-	private _registerRefreshTokenTimeout() {
-		const tokenRefreshTimeoutTime = this._getTokenRefreshTimeoutTime();
+	private _registerRefreshTokenTimeout( timeoutTime?: number ) {
+		const tokenRefreshTimeoutTime = timeoutTime || this._getTokenRefreshTimeoutTime();
 
 		clearTimeout( this._tokenRefreshTimeout );
 

packages/ckeditor5-cloud-services/tests/token/token.js

@@ -7,10 +7,13 @@
 
 import Token from '../../src/token/token.js';
 import CKEditorError from '@ckeditor/ckeditor5-utils/src/ckeditorerror.js';
+import testUtils from '@ckeditor/ckeditor5-core/tests/_utils/utils.js';
 
 describe( 'Token', () => {
 	let requests;
 
+	testUtils.createSinonSandbox();
+
 	beforeEach( () => {
 		requests = [];
 
@@ -241,6 +244,8 @@ describe( 'Token', () => {
 		} );
 
 		it( 'should throw an error if the returned token is wrapped in additional quotes', done => {
+			testUtils.sinon.stub( console, 'warn' );
+
 			const tokenValue = getTestTokenValue();
 			const token = new Token( 'http://token-endpoint', { autoRefresh: false } );
 
@@ -258,6 +263,8 @@ describe( 'Token', () => {
 		} );
 
 		it( 'should throw an error if the returned token is not a valid JWT token', done => {
+			testUtils.sinon.stub( console, 'warn' );
+
 			const token = new Token( 'http://token-endpoint', { autoRefresh: false } );
 
 			token.refreshToken()
@@ -335,6 +342,152 @@ describe( 'Token', () => {
 					expect( error ).to.equal( 'Custom error occurred' );
 				} );
 		} );
+
+		describe( 'refresh failure handling', () => {
+			let clock;
+
+			beforeEach( () => {
+				clock = sinon.useFakeTimers( {
+					toFake: [ 'setTimeout', 'clearTimeout' ]
+				} );
+
+				testUtils.sinon.stub( console, 'warn' );
+			} );
+
+			afterEach( () => {
+				clock.restore();
+			} );
+
+			it( 'should log a warning in the console', () => {
+				const tokenInitValue = getTestTokenValue();
+				const token = new Token( 'http://token-endpoint', { initValue: tokenInitValue, autoRefresh: false } );
+				const promise = token.refreshToken();
+
+				requests[ 0 ].error();
+
+				return promise.then( () => {
+					throw new Error( 'Promise should fail' );
+				}, () => {
+					sinon.assert.calledWithMatch( console.warn, 'token-refresh-failed', { autoRefresh: false } );
+				} );
+			} );
+
+			it( 'should attempt to periodically refresh the token', async () => {
+				const tokenInitValue = getTestTokenValue();
+				const token = new Token( 'http://token-endpoint', { initValue: tokenInitValue, autoRefresh: true } );
+				const promise = token.refreshToken();
+
+				requests[ 0 ].error();
+
+				return promise
+					.then( async () => {
+						throw new Error( 'Promise should fail' );
+					} )
+					.catch( async err => {
+						expect( err ).to.match( /Network Error/ );
+
+						await clock.tickAsync( '05' );
+						expect( requests.length ).to.equal( 2 );
+
+						requests[ 1 ].error();
+
+						await clock.tickAsync( '05' );
+						expect( requests.length ).to.equal( 3 );
+
+						requests[ 2 ].error();
+
+						await clock.tickAsync( '05' );
+						expect( requests.length ).to.equal( 4 );
+					} );
+			} );
+
+			it( 'should restore the regular refresh interval after a successfull refresh', () => {
+				const tokenInitValue = getTestTokenValue();
+				const token = new Token( 'http://token-endpoint', { initValue: tokenInitValue, autoRefresh: true } );
+				const promise = token.refreshToken();
+
+				requests[ 0 ].error();
+
+				return promise
+					.then( async () => {
+						throw new Error( 'Promise should fail' );
+					} )
+					.catch( async err => {
+						expect( err ).to.match( /Network Error/ );
+
+						await clock.tickAsync( '05' );
+						expect( requests.length ).to.equal( 2 );
+
+						requests[ 1 ].respond( 200, '', getTestTokenValue( 20 ) );
+
+						await clock.tickAsync( '05' );
+						// Switched to 10s interval because refresh was successful.
+						expect( requests.length ).to.equal( 2 );
+
+						await clock.tickAsync( '05' );
+						expect( requests.length ).to.equal( 3 );
+
+						requests[ 2 ].respond( 200, '', getTestTokenValue( 20 ) );
+
+						await clock.tickAsync( '10' );
+						expect( requests.length ).to.equal( 4 );
+					} );
+			} );
+
+			it( 'should not auto-refresh after a failure if options.autoRefresh option is false', () => {
+				const tokenInitValue = getTestTokenValue();
+				const token = new Token( 'http://token-endpoint', { initValue: tokenInitValue, autoRefresh: false } );
+				const promise = token.refreshToken();
+
+				requests[ 0 ].error();
+
+				return promise
+					.then( async () => {
+						throw new Error( 'Promise should fail' );
+					} )
+					.catch( async err => {
+						expect( err ).to.match( /Network Error/ );
+
+						await clock.tickAsync( '05' );
+						expect( requests.length ).to.equal( 1 );
+
+						await clock.tickAsync( '10' );
+						expect( requests.length ).to.equal( 1 );
+					} );
+			} );
+
+			it( 'should clear any queued refresh upon manual refreshToken() call to avoid duplicated refreshes', () => {
+				const tokenInitValue = getTestTokenValue();
+				const token = new Token( 'http://token-endpoint', { initValue: tokenInitValue, autoRefresh: true } );
+				const promise = token.refreshToken();
+
+				requests[ 0 ].error();
+
+				return promise
+					.then( async () => {
+						throw new Error( 'Promise should fail' );
+					} )
+					.catch( async err => {
+						expect( err ).to.match( /Network Error/ );
+
+						await clock.tickAsync( '05' );
+						expect( requests.length ).to.equal( 2 );
+
+						token.refreshToken();
+						token.refreshToken();
+						token.refreshToken();
+
+						requests[ 1 ].error();
+						requests[ 2 ].error();
+						requests[ 3 ].error();
+						requests[ 4 ].error();
+
+						await clock.tickAsync( '05' );
+
+						expect( requests.length ).to.equal( 6 );
+					} );
+			} );
+		} );
 	} );
 
 	describe( 'static create()', () => {