Chapter 3. Red Hat build of Keycloak JavaScript adapter Red Hat build of Keycloak comes with a client-side JavaScript library called keycloak-js that can be used to secure web applications. The adapter also comes with built-in support for Cordova applications. The adapter uses OpenID Connect protocol under the covers. You can take a look at the Secure applications and services with OpenID Connect chapter for the more generic information about OpenID Connect endpoints and capabilities. 3.1. Installation We recommend that you install the keycloak-js package from NPM: npm install keycloak-js 3.2. Red Hat build of Keycloak server configuration One important thing to consider about using client-side applications is that the client has to be a public client as there is no secure way to store client credentials in a client-side application. This consideration makes it very important to make sure the redirect URIs you have configured for the client are correct and as specific as possible. To use the adapter, create a client for your application in the Red Hat build of Keycloak Admin Console. Make the client public by toggling Client authentication to Off on the Capability config page. You also need to configure Valid Redirect URIs and Web Origins . Be as specific as possible as failing to do so may result in a security vulnerability. 3.3. Using the adapter The following example shows how to initialize the adapter. Make sure that you replace the options passed to the Keycloak constructor with those of the client you have configured. import Keycloak from 'keycloak-js'; const keycloak = new Keycloak({ url: "http://keycloak-server", realm: "my-realm", clientId: "my-app" }); try { const authenticated = await keycloak.init(); if (authenticated) { console.log('User is authenticated'); } else { console.log('User is not authenticated'); } } catch (error) { console.error('Failed to initialize adapter:', error); } To authenticate, you call the login function. Two options exist to make the adapter automatically authenticate. You can pass login-required or check-sso to the init() function. login-required authenticates the client if the user is logged in to Red Hat build of Keycloak or displays the login page if the user is not logged in. check-sso only authenticates the client if the user is already logged in. If the user is not logged in, the browser is redirected back to the application and remains unauthenticated. You can configure a silent check-sso option. With this feature enabled, your browser will not perform a full redirect to the Red Hat build of Keycloak server and back to your application, but this action will be performed in a hidden iframe. Therefore, your application resources are only loaded and parsed once by the browser, namely when the application is initialized and not again after the redirect back from Red Hat build of Keycloak to your application. This approach is particularly useful in case of SPAs (Single Page Applications). To enable the silent check-sso , you provide a silentCheckSsoRedirectUri attribute in the init method. Make sure this URI is a valid endpoint in the application; it must be configured as a valid redirect for the client in the Red Hat build of Keycloak Admin Console: await keycloak.init({ onLoad: 'check-sso', silentCheckSsoRedirectUri: `USD{location.origin}/silent-check-sso.html` }); The page at the silent check-sso redirect uri is loaded in the iframe after successfully checking your authentication state and retrieving the tokens from the Red Hat build of Keycloak server. It has no other task than sending the received tokens to the main application and should only look like this: <!doctype html> <html> <body> <script> parent.postMessage(location.href, location.origin); </script> </body> </html> Remember that this page must be served by your application at the specified location in silentCheckSsoRedirectUri and is not part of the adapter. Warning Silent check-sso functionality is limited in some modern browsers. Please see the Modern Browsers with Tracking Protection Section . To enable login-required set onLoad to login-required and pass to the init method: await keycloak.init({ onLoad: 'login-required' }); After the user is authenticated the application can make requests to RESTful services secured by Red Hat build of Keycloak by including the bearer token in the Authorization header. For example: async function fetchUsers() { const response = await fetch('/api/users', { headers: { accept: 'application/json', authorization: `Bearer USD{keycloak.token}` } }); return response.json(); } One thing to keep in mind is that the access token by default has a short life expiration so you may need to refresh the access token prior to sending the request. You refresh this token by calling the updateToken() method. This method returns a Promise, which makes it easy to invoke the service only if the token was successfully refreshed and displays an error to the user if it was not refreshed. For example: try { await keycloak.updateToken(30); } catch (error) { console.error('Failed to refresh token:', error); } const users = await fetchUsers(); Note Both access and refresh token are stored in memory and are not persisted in any kind of storage. Therefore, these tokens should never be persisted to prevent hijacking attacks. 3.4. Session Status iframe By default, the adapter creates a hidden iframe that is used to detect if a Single-Sign Out has occurred. This iframe does not require any network traffic. Instead the status is retrieved by looking at a special status cookie. This feature can be disabled by setting checkLoginIframe: false in the options passed to the init() method. You should not rely on looking at this cookie directly. Its format can change and it's also associated with the URL of the Red Hat build of Keycloak server, not your application. Warning Session Status iframe functionality is limited in some modern browsers. Please see Modern Browsers with Tracking Protection Section . 3.5. Implicit and hybrid flow By default, the adapter uses the Authorization Code flow. With this flow, the Red Hat build of Keycloak server returns an authorization code, not an authentication token, to the application. The JavaScript adapter exchanges the code for an access token and a refresh token after the browser is redirected back to the application. Red Hat build of Keycloak also supports the Implicit flow where an access token is sent immediately after successful authentication with Red Hat build of Keycloak. This flow may have better performance than the standard flow because no additional request exists to exchange the code for tokens, but it has implications when the access token expires. However, sending the access token in the URL fragment can be a security vulnerability. For example the token could be leaked through web server logs and or browser history. To enable implicit flow, you enable the Implicit Flow Enabled flag for the client in the Red Hat build of Keycloak Admin Console. You also pass the parameter flow with the value implicit to init method: await keycloak.init({ flow: 'implicit' }) Note that only an access token is provided and no refresh token exists. This situation means that once the access token has expired, the application has to redirect to Red Hat build of Keycloak again to obtain a new access token. Red Hat build of Keycloak also supports the Hybrid flow. This flow requires the client to have both the Standard Flow and Implicit Flow enabled in the Admin Console. The Red Hat build of Keycloak server then sends both the code and tokens to your application. The access token can be used immediately while the code can be exchanged for access and refresh tokens. Similar to the implicit flow, the hybrid flow is good for performance because the access token is available immediately. But, the token is still sent in the URL, and the security vulnerability mentioned earlier may still apply. One advantage in the Hybrid flow is that the refresh token is made available to the application. For the Hybrid flow, you need to pass the parameter flow with value hybrid to the init method: await keycloak.init({ flow: 'hybrid' }); 3.6. Hybrid Apps with Cordova Red Hat build of Keycloak supports hybrid mobile apps developed with Apache Cordova . The adapter has two modes for this: cordova and cordova-native : The default is cordova , which the adapter automatically selects if no adapter type has been explicitly configured and window.cordova is present. When logging in, it opens an InApp Browser that lets the user interact with Red Hat build of Keycloak and afterwards returns to the app by redirecting to http://localhost . Because of this behavior, you whitelist this URL as a valid redirect-uri in the client configuration section of the Admin Console. While this mode is easy to set up, it also has some disadvantages: The InApp-Browser is a browser embedded in the app and is not the phone's default browser. Therefore it will have different settings and stored credentials will not be available. The InApp-Browser might also be slower, especially when rendering more complex themes. There are security concerns to consider, before using this mode, such as that it is possible for the app to gain access to the credentials of the user, as it has full control of the browser rendering the login page, so do not allow its use in apps you do not trust. The alternative mode is`cordova-native`, which takes a different approach. It opens the login page using the system's browser. After the user has authenticated, the browser redirects back into the application using a special URL. From there, the Red Hat build of Keycloak adapter can finish the login by reading the code or token from the URL. You can activate the native mode by passing the adapter type cordova-native to the init() method: await keycloak.init({ adapter: 'cordova-native' }); This adapter requires two additional plugins: cordova-plugin-browsertab : allows the app to open webpages in the system's browser cordova-plugin-deeplinks : allow the browser to redirect back to your app by special URLs The technical details for linking to an app differ on each platform and special setup is needed. Please refer to the Android and iOS sections of the deeplinks plugin documentation for further instructions. Different kinds of links exist for opening apps: custom schemes, such as myapp://login or android-app://com.example.myapp/https/example.com/login . Universal Links (iOS) / Deep Links (Android) . While the former are easier to set up and tend to work more reliably, the latter offer extra security because they are unique and only the owner of a domain can register them. Custom-URLs are deprecated on iOS. For best reliability, we recommend that you use universal links combined with a fallback site that uses a custom-url link. Furthermore, we recommend the following steps to improve compatibility with the adapter: Universal Links on iOS seem to work more reliably with response-mode set to query To prevent Android from opening a new instance of your app on redirect add the following snippet to config.xml : <preference name="AndroidLaunchMode" value="singleTask" /> 3.7. Custom Adapters In some situations, you may need to run the adapter in environments that are not supported by default, such as Capacitor. To use the JavasScript client in these environments, you can pass a custom adapter. For example, a third-party library could provide such an adapter to make it possible to reliably run the adapter: import Keycloak from 'keycloak-js'; import KeycloakCapacitorAdapter from 'keycloak-capacitor-adapter'; const keycloak = new Keycloak({ url: "http://keycloak-server", realm: "my-realm", clientId: "my-app" }); await keycloak.init({ adapter: KeycloakCapacitorAdapter, }); This specific package does not exist, but it gives a pretty good example of how such an adapter could be passed into the client. It's also possible to make your own adapter, to do so you will have to implement the methods described in the KeycloakAdapter interface. For example the following TypeScript code ensures that all the methods are properly implemented: import Keycloak, { KeycloakAdapter } from 'keycloak-js'; // Implement the 'KeycloakAdapter' interface so that all required methods are guaranteed to be present. const MyCustomAdapter: KeycloakAdapter = { async login(options) { // Write your own implementation here. } // The other methods go here... }; const keycloak = new Keycloak({ url: "http://keycloak-server", realm: "my-realm", clientId: "my-app" }); await keycloak.init({ adapter: MyCustomAdapter, }); Naturally you can also do this without TypeScript by omitting the type information, but ensuring implementing the interface properly will then be left entirely up to you. 3.8. Modern Browsers with Tracking Protection In the latest versions of some browsers, various cookies policies are applied to prevent tracking of the users by third parties, such as SameSite in Chrome or completely blocked third-party cookies. Those policies are likely to become more restrictive and adopted by other browsers over time. Eventually cookies in third-party contexts may become completely unsupported and blocked by the browsers. As a result, the affected adapter features might ultimately be deprecated. The adapter relies on third-party cookies for Session Status iframe, silent check-sso and partially also for regular (non-silent) check-sso . Those features have limited functionality or are completely disabled based on how restrictive the browser is regarding cookies. The adapter tries to detect this setting and reacts accordingly. 3.8.1. Browsers with "SameSite=Lax by Default" Policy All features are supported if SSL / TLS connection is configured on the Red Hat build of Keycloak side as well as on the application side. For example, Chrome is affected starting with version 84. 3.8.2. Browsers with Blocked Third-Party Cookies Session Status iframe is not supported and is automatically disabled if such browser behavior is detected by the adapter. This means the adapter cannot use a session cookie for Single Sign-Out detection and must rely purely on tokens. As a result, when a user logs out in another window, the application using the adapter will not be logged out until the application tries to refresh the Access Token. Therefore, consider setting the Access Token Lifespan to a relatively short time, so that the logout is detected as soon as possible. For more details, see Session and Token Timeouts . Silent check-sso is not supported and falls back to regular (non-silent) check-sso by default. This behavior can be changed by setting silentCheckSsoFallback: false in the options passed to the init method. In this case, check-sso will be completely disabled if restrictive browser behavior is detected. Regular check-sso is affected as well. Since Session Status iframe is unsupported, an additional redirect to Red Hat build of Keycloak has to be made when the adapter is initialized to check the user's login status. This check is different from the standard behavior when the iframe is used to tell whether the user is logged in, and the redirect is performed only when the user is logged out. An affected browser is for example Safari starting with version 13.1. 3.9. API Reference 3.9.1. Constructor // Recommended way to initialize the adapter. new Keycloak({ url: "http://keycloak-server", realm: "my-realm", clientId: "my-app" }); // Alternatively a string to the path of the `keycloak.json` file. // Has some performance implications, as it will load the keycloak.json file from the server. // This version might also change in the future and is therefore not recommended. new Keycloak("http://keycloak-server/keycloak.json"); 3.9.2. Properties authenticated Is true if the user is authenticated, false otherwise. token The base64 encoded token that can be sent in the Authorization header in requests to services. tokenParsed The parsed token as a JavaScript object. subject The user id. idToken The base64 encoded ID token. idTokenParsed The parsed id token as a JavaScript object. realmAccess The realm roles associated with the token. resourceAccess The resource roles associated with the token. refreshToken The base64 encoded refresh token that can be used to retrieve a new token. refreshTokenParsed The parsed refresh token as a JavaScript object. timeSkew The estimated time difference between the browser time and the Red Hat build of Keycloak server in seconds. This value is just an estimation, but is accurate enough when determining if a token is expired or not. responseMode Response mode passed in init (default value is fragment). flow Flow passed in init. adapter Allows you to override the way that redirects and other browser-related functions will be handled by the library. Available options: "default" - the library uses the browser api for redirects (this is the default) "cordova" - the library will try to use the InAppBrowser cordova plugin to load keycloak login/registration pages (this is used automatically when the library is working in a cordova ecosystem) "cordova-native" - the library tries to open the login and registration page using the phone's system browser using the BrowserTabs cordova plugin. This requires extra setup for redirecting back to the app (see Section 3.6, "Hybrid Apps with Cordova" ). "custom" - allows you to implement a custom adapter (only for advanced use cases) responseType Response type sent to Red Hat build of Keycloak with login requests. This is determined based on the flow value used during initialization, but can be overridden by setting this value. 3.9.3. Methods init(options) Called to initialize the adapter. Options is an Object, where: useNonce - Adds a cryptographic nonce to verify that the authentication response matches the request (default is true ). onLoad - Specifies an action to do on load. Supported values are login-required or check-sso . silentCheckSsoRedirectUri - Set the redirect uri for silent authentication check if onLoad is set to 'check-sso'. silentCheckSsoFallback - Enables fall back to regular check-sso when silent check-sso is not supported by the browser (default is true ). token - Set an initial value for the token. refreshToken - Set an initial value for the refresh token. idToken - Set an initial value for the id token (only together with token or refreshToken). scope - Set the default scope parameter to the Red Hat build of Keycloak login endpoint. Use a space-delimited list of scopes. Those typically reference Client scopes defined on a particular client. Note that the scope openid will always be added to the list of scopes by the adapter. For example, if you enter the scope options address phone , then the request to Red Hat build of Keycloak will contain the scope parameter scope=openid address phone . Note that the default scope specified here is overwritten if the login() options specify scope explicitly. timeSkew - Set an initial value for skew between local time and Red Hat build of Keycloak server in seconds (only together with token or refreshToken). checkLoginIframe - Set to enable/disable monitoring login state (default is true ). checkLoginIframeInterval - Set the interval to check login state (default is 5 seconds). responseMode - Set the OpenID Connect response mode send to Red Hat build of Keycloak server at login request. Valid values are query or fragment . Default value is fragment , which means that after successful authentication will Red Hat build of Keycloak redirect to JavaScript application with OpenID Connect parameters added in URL fragment. This is generally safer and recommended over query . flow - Set the OpenID Connect flow. Valid values are standard , implicit or hybrid . enableLogging - Enables logging messages from Keycloak to the console (default is false ). pkceMethod - The method for Proof Key Code Exchange ( PKCE ) to use. Configuring this value enables the PKCE mechanism. Available options: "S256" - The SHA256 based PKCE method (default) false - PKCE is disabled. acrValues - Generates the acr_values parameter which refers to authentication context class reference and allows clients to declare the required assurance level requirements, e.g. authentication mechanisms. See Section 4. acr_values request values and level of assurance in OpenID Connect MODRNA Authentication Profile 1.0 . messageReceiveTimeout - Set a timeout in milliseconds for waiting for message responses from the Keycloak server. This is used, for example, when waiting for a message during 3rd party cookies check. The default value is 10000. locale - When onLoad is 'login-required', sets the 'ui_locales' query param in compliance with section 3.1.2.1 of the OIDC 1.0 specification . Returns a promise that resolves when initialization completes. login(options) Redirects to login form, returns a Promise. Options is an optional Object, where: redirectUri - Specifies the uri to redirect to after login. prompt - This parameter allows to slightly customize the login flow on the Red Hat build of Keycloak server side. For example, enforce displaying the login screen in case of value login . Or enforce displaying of consent screen for the value consent in case that client has Consent Required . Finally it is possible use the value none to make sure that login screen is not displayed to the user, which is useful just to check SSO for the case when user was already authenticated before (This is related to the onLoad check with value check-sso described above). maxAge - Used just if user is already authenticated. Specifies maximum time since the authentication of user happened. If user is already authenticated for longer time than maxAge , the SSO is ignored and he will need to re-authenticate again. loginHint - Used to pre-fill the username/email field on the login form. scope - Override the scope configured in init with a different value for this specific login. idpHint - Used to tell Red Hat build of Keycloak to skip showing the login page and automatically redirect to the specified identity provider instead. More info in the Identity Provider documentation . acr - Contains the information about acr claim, which will be sent inside claims parameter to the Red Hat build of Keycloak server. Typical usage is for step-up authentication. Example of use { values: ["silver", "gold"], essential: true } . See OpenID Connect specification and Step-up authentication documentation for more details. acrValues - Generates the acr_values parameter which refers to authentication context class reference and allows clients to declare the required assurance level requirements, e.g. authentication mechanisms. See Section 4. acr_values request values and level of assurance in OpenID Connect MODRNA Authentication Profile 1.0 . action - If the value is register , the user is redirected to the registration page. See Registration requested by client section for more details. If the value is UPDATE_PASSWORD or another supported required action, the user will be redirected to the reset password page or the other required action page. However, if the user is not authenticated, the user will be sent to the login page and redirected after authentication. See Application Initiated Action section for more details. locale - Sets the 'ui_locales' query param in compliance with section 3.1.2.1 of the OIDC 1.0 specification . cordovaOptions - Specifies the arguments that are passed to the Cordova in-app-browser (if applicable). Options hidden and location are not affected by these arguments. All available options are defined at https://cordova.apache.org/docs/en/latest/reference/cordova-plugin-inappbrowser/ . Example of use: { zoom: "no", hardwareback: "yes" } ; createLoginUrl(options) Returns a Promise containing the URL to login form. Options is an optional Object, which supports same options as the function login . logout(options) Redirects to logout. Options is an Object, where: redirectUri - Specifies the uri to redirect to after logout. createLogoutUrl(options) Returns the URL to log out the user. Options is an Object, where: redirectUri - Specifies the uri to redirect to after logout. register(options) Redirects to registration form. Shortcut for login with option action = 'register' Options are same as for the login method but 'action' is set to 'register' createRegisterUrl(options) Returns a Promise containing the url to registration page. Shortcut for createLoginUrl with option action = 'register' Options are same as for the createLoginUrl method but 'action' is set to 'register' accountManagement() Redirects to the Account Console. createAccountUrl(options) Returns the URL to the Account Console. Options is an Object, where: redirectUri - Specifies the uri to redirect to when redirecting back to the application. hasRealmRole(role) Returns true if the token has the given realm role. hasResourceRole(role, resource) Returns true if the token has the given role for the resource (resource is optional, if not specified clientId is used). loadUserProfile() Loads the users profile. Returns a promise that resolves with the profile. For example: try { const profile = await keycloak.loadUserProfile(); console.log('Retrieved user profile:', profile); } catch (error) { console.error('Failed to load user profile:', error); } isTokenExpired(minValidity) Returns true if the token has less than minValidity seconds left before it expires (minValidity is optional, if not specified 0 is used). updateToken(minValidity) If the token expires within minValidity seconds (minValidity is optional, if not specified 5 is used) the token is refreshed. If -1 is passed as the minValidity, the token will be forcibly refreshed. If the session status iframe is enabled, the session status is also checked. Returns a promise that resolves with a boolean indicating whether or not the token has been refreshed. For example: try { const refreshed = await keycloak.updateToken(5); console.log(refreshed ? 'Token was refreshed' : 'Token is still valid'); } catch (error) { console.error('Failed to refresh the token:', error); } clearToken() Clear authentication state, including tokens. This can be useful if application has detected the session was expired, for example if updating token fails. Invoking this results in onAuthLogout callback listener being invoked. 3.9.4. Callback Events The adapter supports setting callback listeners for certain events. Keep in mind that these have to be set before the call to the init() method. For example: keycloak.onAuthSuccess = () => console.log('Authenticated!'); The available events are: onReady(authenticated) - Called when the adapter is initialized. onAuthSuccess - Called when a user is successfully authenticated. onAuthError - Called if there was an error during authentication. onAuthRefreshSuccess - Called when the token is refreshed. onAuthRefreshError - Called if there was an error while trying to refresh the token. onAuthLogout - Called if the user is logged out (will only be called if the session status iframe is enabled, or in Cordova mode). onTokenExpired - Called when the access token is expired. If a refresh token is available the token can be refreshed with updateToken, or in cases where it is not (that is, with implicit flow) you can redirect to the login screen to obtain a new access token.

Commands:
npm install keycloak-js
import Keycloak from 'keycloak-js'; const keycloak = new Keycloak({ url: "http://keycloak-server", realm: "my-realm", clientId: "my-app" }); try { const authenticated = await keycloak.init(); if (authenticated) { console.log('User is authenticated'); } else { console.log('User is not authenticated'); } } catch (error) { console.error('Failed to initialize adapter:', error); }
await keycloak.init({ onLoad: 'check-sso', silentCheckSsoRedirectUri: `USD{location.origin}/silent-check-sso.html` });
<!doctype html> <html> <body> <script> parent.postMessage(location.href, location.origin); </script> </body> </html>
await keycloak.init({ onLoad: 'login-required' });
async function fetchUsers() { const response = await fetch('/api/users', { headers: { accept: 'application/json', authorization: `Bearer USD{keycloak.token}` } }); return response.json(); }
try { await keycloak.updateToken(30); } catch (error) { console.error('Failed to refresh token:', error); } const users = await fetchUsers();
await keycloak.init({ flow: 'implicit' })
await keycloak.init({ flow: 'hybrid' });
await keycloak.init({ adapter: 'cordova-native' });
<preference name="AndroidLaunchMode" value="singleTask" />
import Keycloak from 'keycloak-js'; import KeycloakCapacitorAdapter from 'keycloak-capacitor-adapter'; const keycloak = new Keycloak({ url: "http://keycloak-server", realm: "my-realm", clientId: "my-app" }); await keycloak.init({ adapter: KeycloakCapacitorAdapter, });
import Keycloak, { KeycloakAdapter } from 'keycloak-js'; // Implement the 'KeycloakAdapter' interface so that all required methods are guaranteed to be present. const MyCustomAdapter: KeycloakAdapter = { async login(options) { // Write your own implementation here. } // The other methods go here }; const keycloak = new Keycloak({ url: "http://keycloak-server", realm: "my-realm", clientId: "my-app" }); await keycloak.init({ adapter: MyCustomAdapter, });
// Recommended way to initialize the adapter. new Keycloak({ url: "http://keycloak-server", realm: "my-realm", clientId: "my-app" }); // Alternatively a string to the path of the `keycloak.json` file. // Has some performance implications, as it will load the keycloak.json file from the server. // This version might also change in the future and is therefore not recommended. new Keycloak("http://keycloak-server/keycloak.json");
try { const profile = await keycloak.loadUserProfile(); console.log('Retrieved user profile:', profile); } catch (error) { console.error('Failed to load user profile:', error); }
try { const refreshed = await keycloak.updateToken(5); console.log(refreshed ? 'Token was refreshed' : 'Token is still valid'); } catch (error) { console.error('Failed to refresh the token:', error); }
keycloak.onAuthSuccess = () => console.log('Authenticated!');