Add custom domain support to callable functions

.changeset/poor-eagles-think.md

@@ -0,0 +1,5 @@
+---
+'@firebase/functions': minor
+---
+
+Allow setting a custom domain for callable Cloud Functions.

packages-exp/functions-exp/src/api.ts

@@ -35,20 +35,22 @@ import {
 /**
  * Returns a Functions instance for the given app.
  * @param app - The FirebaseApp to use.
- * @param region - The region the callable functions are located in.
+ * @param regionOrCustomDomain - one of:
+ *   a) The region the callable functions are located in (ex: us-central1)
+ *   b) A custom domain hosting the callable functions (ex: https://mydomain.com)
  * @public
  */
 export function getFunctions(
   app: FirebaseApp,
-  region: string = DEFAULT_REGION
+  regionOrCustomDomain: string = DEFAULT_REGION
 ): Functions {
   // Dependencies
   const functionsProvider: Provider<'functions'> = _getProvider(
     app,
     FUNCTIONS_TYPE
   );
   const functionsInstance = functionsProvider.getImmediate({
-    identifier: region
+    identifier: regionOrCustomDomain
   });
   return functionsInstance;
 }

packages-exp/functions-exp/src/config.ts

@@ -30,7 +30,7 @@ export const DEFAULT_REGION = 'us-central1';
 export function registerFunctions(fetchImpl: typeof fetch): void {
   const factory: InstanceFactory<'functions'> = (
     container: ComponentContainer,
-    region?: string
+    regionOrCustomDomain?: string
   ) => {
     // Dependencies
     const app = container.getProvider('app-exp').getImmediate();
@@ -42,7 +42,7 @@ export function registerFunctions(fetchImpl: typeof fetch): void {
       app,
       authProvider,
       messagingProvider,
-      region,
+      regionOrCustomDomain,
       fetchImpl
     );
   };

packages-exp/functions-exp/src/service.test.ts

@@ -64,5 +64,19 @@ describe('Firebase Functions > Service', () => {
         'http://localhost:5005/my-project/my-region/foo'
       );
     });
+
+    it('correctly sets custom domain', () => {
+      service = createTestService(app, 'https://mydomain.com');
+      assert.equal(service._url('foo'), 'https://mydomain.com/foo');
+    });
+
+    it('prefers emulator to custom domain', () => {
+      const service = createTestService(app, 'https://mydomain.com');
+      useFunctionsEmulator(service, 'http://localhost:5005');
+      assert.equal(
+        service._url('foo'),
+        'http://localhost:5005/my-project/us-central1/foo'
+      );
+    });
   });
 });

packages-exp/functions-exp/src/service.ts

@@ -75,6 +75,8 @@ export class FunctionsService implements _FirebaseService {
   emulatorOrigin: string | null = null;
   cancelAllRequests: Promise<void>;
   deleteService!: () => Promise<void>;
+  region: string;
+  customDomain: string | null;
 
   /**
    * Creates a new Functions service for the given app.
@@ -84,7 +86,7 @@ export class FunctionsService implements _FirebaseService {
     readonly app: FirebaseApp,
     authProvider: Provider<FirebaseAuthInternalName>,
     messagingProvider: Provider<FirebaseMessagingName>,
-    readonly region: string = DEFAULT_REGION,
+    regionOrCustomDomain: string = DEFAULT_REGION,
     readonly fetchImpl: typeof fetch
   ) {
     this.contextProvider = new ContextProvider(authProvider, messagingProvider);
@@ -94,6 +96,16 @@ export class FunctionsService implements _FirebaseService {
         return Promise.resolve(resolve());
       };
     });
+
+    // Resolve the region or custom domain overload by attempting to parse it.
+    try {
+      const url = new URL(regionOrCustomDomain);
+      this.customDomain = url.origin;
+      this.region = DEFAULT_REGION;
+    } catch (e) {
+      this.customDomain = null;
+      this.region = regionOrCustomDomain;
+    }
   }
 
   _delete(): Promise<void> {
@@ -107,12 +119,16 @@ export class FunctionsService implements _FirebaseService {
    */
   _url(name: string): string {
     const projectId = this.app.options.projectId;
-    const region = this.region;
     if (this.emulatorOrigin !== null) {
       const origin = this.emulatorOrigin;
-      return `${origin}/${projectId}/${region}/${name}`;
+      return `${origin}/${projectId}/${this.region}/${name}`;
     }
-    return `https://${region}-${projectId}.cloudfunctions.net/${name}`;
+
+    if (this.customDomain !== null) {
+      return `${this.customDomain}/${name}`;
+    }
+
+    return `https://${this.region}-${projectId}.cloudfunctions.net/${name}`;
   }
 }
 

packages-exp/functions-types-exp/index.d.ts

@@ -54,6 +54,12 @@ export interface Functions {
    * Default is `us-central-1`.
    */
   region: string;
+
+  /**
+   * A custom domain hosting the callable Cloud Functions.
+   * ex: https://mydomain.com
+   */
+  customDomain: string | null;
 }
 
 /**

packages/functions/index.ts

@@ -32,6 +32,6 @@ declare module '@firebase/app-types' {
     };
   }
   interface FirebaseApp {
-    functions?(region?: string): types.FirebaseFunctions;
+    functions?(regionOrCustomDomain?: string): types.FirebaseFunctions;
   }
 }

packages/functions/src/api/service.ts

@@ -86,17 +86,21 @@ export class Service implements FirebaseFunctions, FirebaseService {
   private emulatorOrigin: string | null = null;
   private cancelAllRequests: Promise<void>;
   private deleteService!: () => void;
+  private region: string;
+  private customDomain: string | null;
 
   /**
-   * Creates a new Functions service for the given app and (optional) region.
+   * Creates a new Functions service for the given app and (optional) region or custom domain.
    * @param app_ The FirebaseApp to use.
-   * @param region_ The region to call functions in.
+   * @param regionOrCustomDomain_ one of:
+   *   a) A region to call functions from, such as us-central1
+   *   b) A custom domain to use as a functions prefix, such as https://mydomain.com
    */
   constructor(
     private app_: FirebaseApp,
     authProvider: Provider<FirebaseAuthInternalName>,
     messagingProvider: Provider<FirebaseMessagingName>,
-    private region_: string = 'us-central1',
+    regionOrCustomDomain_: string = 'us-central1',
     readonly fetchImpl: typeof fetch
   ) {
     this.contextProvider = new ContextProvider(authProvider, messagingProvider);
@@ -106,6 +110,16 @@ export class Service implements FirebaseFunctions, FirebaseService {
         return resolve();
       };
     });
+
+    // Resolve the region or custom domain overload by attempting to parse it.
+    try {
+      const url = new URL(regionOrCustomDomain_);
+      this.customDomain = url.origin;
+      this.region = 'us-central1';
+    } catch (e) {
+      this.customDomain = null;
+      this.region = regionOrCustomDomain_;
+    }
   }
 
   get app(): FirebaseApp {
@@ -124,12 +138,16 @@ export class Service implements FirebaseFunctions, FirebaseService {
    */
   _url(name: string): string {
     const projectId = this.app_.options.projectId;
-    const region = this.region_;
     if (this.emulatorOrigin !== null) {
       const origin = this.emulatorOrigin;
-      return `${origin}/${projectId}/${region}/${name}`;
+      return `${origin}/${projectId}/${this.region}/${name}`;
     }
-    return `https://${region}-${projectId}.cloudfunctions.net/${name}`;
+
+    if (this.customDomain !== null) {
+      return `${this.customDomain}/${name}`;
+    }
+
+    return `https://${this.region}-${projectId}.cloudfunctions.net/${name}`;
   }
 
   /**

packages/functions/src/config.ts

@@ -37,14 +37,23 @@ export function registerFunctions(
     Functions: Service
   };
 
-  function factory(container: ComponentContainer, region?: string): Service {
+  function factory(
+    container: ComponentContainer,
+    regionOrCustomDomain?: string
+  ): Service {
     // Dependencies
     const app = container.getProvider('app').getImmediate();
     const authProvider = container.getProvider('auth-internal');
     const messagingProvider = container.getProvider('messaging');
 
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    return new Service(app, authProvider, messagingProvider, region, fetchImpl);
+    return new Service(
+      app,
+      authProvider,
+      messagingProvider,
+      regionOrCustomDomain,
+      fetchImpl
+    );
   }
   instance.INTERNAL.registerComponent(
     new Component(FUNCTIONS_TYPE, factory, ComponentType.PUBLIC)

packages/functions/test/service.test.ts

@@ -42,19 +42,33 @@ describe('Firebase Functions > Service', () => {
     });
   });
 
-  describe('custom region constructor', () => {
+  describe('custom region/domain constructor', () => {
     const app: any = {
       options: {
         projectId: 'my-project'
       }
     };
-    const service = createTestService(app, 'my-region');
 
-    it('has valid urls', () => {
+    it('can use custom region', () => {
+      const service = createTestService(app, 'my-region');
       assert.equal(
         service._url('foo'),
         'https://my-region-my-project.cloudfunctions.net/foo'
       );
     });
+
+    it('can use custom domain', () => {
+      const service = createTestService(app, 'https://mydomain.com');
+      assert.equal(service._url('foo'), 'https://mydomain.com/foo');
+    });
+
+    it('prefers emulator to custom domain', () => {
+      const service = createTestService(app, 'https://mydomain.com');
+      service.useFunctionsEmulator('http://localhost:5005');
+      assert.equal(
+        service._url('foo'),
+        'http://localhost:5005/my-project/us-central1/foo'
+      );
+    });
   });
 });

packages/functions/test/utils.ts

@@ -43,7 +43,7 @@ export function makeFakeApp(options: FirebaseOptions = {}): FirebaseApp {
 
 export function createTestService(
   app: FirebaseApp,
-  region?: string,
+  regionOrCustomDomain?: string,
   authProvider = new Provider<FirebaseAuthInternalName>(
     'auth-internal',
     new ComponentContainer('test')
@@ -59,7 +59,7 @@ export function createTestService(
     app,
     authProvider,
     messagingProvider,
-    region,
+    regionOrCustomDomain,
     fetchImpl
   );
   const useEmulator = !!process.env.FIREBASE_FUNCTIONS_EMULATOR_ORIGIN;