From 3ee0f22aeaac42f569f7dfd091fa8fca074d50aa Mon Sep 17 00:00:00 2001
From: Sam <samstern@google.com>
Date: Tue, 22 Sep 2020 15:42:03 +0100
Subject: [PATCH 1/5] Add custom domain support to callable functions

---
 packages/functions/index.ts             |  2 +-
 packages/functions/src/api/service.ts   | 26 +++++++++++++++++++++----
 packages/functions/src/config.ts        |  4 ++--
 packages/functions/test/service.test.ts | 25 ++++++++++++++++++++++++
 packages/functions/test/utils.ts        |  4 ++--
 5 files changed, 52 insertions(+), 9 deletions(-)

diff --git a/packages/functions/index.ts b/packages/functions/index.ts
index 6a797b92029..1996574328d 100644
--- a/packages/functions/index.ts
+++ b/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;
   }
 }
diff --git a/packages/functions/src/api/service.ts b/packages/functions/src/api/service.ts
index 601f365344b..c59aacce0fd 100644
--- a/packages/functions/src/api/service.ts
+++ b/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 = 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 +110,15 @@ 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.region = regionOrCustomDomain_;
+    }
   }
 
   get app(): FirebaseApp {
@@ -124,11 +137,16 @@ export class Service implements FirebaseFunctions, FirebaseService {
    */
   _url(name: string): string {
     const projectId = this.app_.options.projectId;
-    const region = this.region_;
+    const region = this.region;
     if (this.emulatorOrigin !== null) {
       const origin = this.emulatorOrigin;
       return `${origin}/${projectId}/${region}/${name}`;
     }
+
+    if (this.customDomain !== null) {
+      return `${this.customDomain}/${name}`;
+    }
+
     return `https://${region}-${projectId}.cloudfunctions.net/${name}`;
   }
 
diff --git a/packages/functions/src/config.ts b/packages/functions/src/config.ts
index c1cfdef7dac..dd5f6ae88b6 100644
--- a/packages/functions/src/config.ts
+++ b/packages/functions/src/config.ts
@@ -37,14 +37,14 @@ 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)
diff --git a/packages/functions/test/service.test.ts b/packages/functions/test/service.test.ts
index 197d8c6f741..93224a3440f 100644
--- a/packages/functions/test/service.test.ts
+++ b/packages/functions/test/service.test.ts
@@ -40,6 +40,31 @@ describe('Firebase Functions > Service', () => {
         'http://localhost:5005/my-project/us-central1/foo'
       );
     });
+
+    it('can use custom region', () => {
+      const customRegionService = createTestService(app, 'us-west2');     
+      assert.equal(
+        customRegionService._url('foo'),
+        'https://us-west2-my-project.cloudfunctions.net/foo'
+      );
+    });
+
+    it('can use custom domain', () => {
+      const customDomainService = createTestService(app, 'https://mydomain.com');
+      assert.equal(
+        customDomainService._url('foo'),
+        'https://mydomain.com/foo'
+      );
+    });
+
+    it('prefers emulator to custom domain', () => {
+      const customDomainService = createTestService(app, 'https://mydomain.com');
+      customDomainService.useFunctionsEmulator('http://localhost:5005');
+      assert.equal(
+        customDomainService._url('foo'),
+        'http://localhost:5005/my-project/us-central1/foo'
+      );
+    });
   });
 
   describe('custom region constructor', () => {
diff --git a/packages/functions/test/utils.ts b/packages/functions/test/utils.ts
index 56c6f52201f..4ffdd8c868a 100644
--- a/packages/functions/test/utils.ts
+++ b/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;

From 75b9e4ef603d0fc99952d1eafd028ff9ce2dddce Mon Sep 17 00:00:00 2001
From: Sam <samstern@google.com>
Date: Thu, 24 Sep 2020 13:00:03 +0100
Subject: [PATCH 2/5] Implement functions-exp

---
 packages-exp/functions-exp/src/api.ts         |  8 ++--
 packages-exp/functions-exp/src/config.ts      |  4 +-
 .../functions-exp/src/service.test.ts         | 17 ++++++++
 packages-exp/functions-exp/src/service.ts     | 24 +++++++++--
 packages-exp/functions-types-exp/index.d.ts   |  6 +++
 packages/functions/src/api/service.ts         |  8 ++--
 packages/functions/test/service.test.ts       | 40 ++++++++-----------
 7 files changed, 70 insertions(+), 37 deletions(-)

diff --git a/packages-exp/functions-exp/src/api.ts b/packages-exp/functions-exp/src/api.ts
index 01d786f7737..3d7ff92f740 100644
--- a/packages-exp/functions-exp/src/api.ts
+++ b/packages-exp/functions-exp/src/api.ts
@@ -35,12 +35,14 @@ 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(
@@ -48,7 +50,7 @@ export function getFunctions(
     FUNCTIONS_TYPE
   );
   const functionsInstance = functionsProvider.getImmediate({
-    identifier: region
+    identifier: regionOrCustomDomain
   });
   return functionsInstance;
 }
diff --git a/packages-exp/functions-exp/src/config.ts b/packages-exp/functions-exp/src/config.ts
index 021235d6483..9279835b2c7 100644
--- a/packages-exp/functions-exp/src/config.ts
+++ b/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
     );
   };
diff --git a/packages-exp/functions-exp/src/service.test.ts b/packages-exp/functions-exp/src/service.test.ts
index 79a4580976a..42b8e9eeb67 100644
--- a/packages-exp/functions-exp/src/service.test.ts
+++ b/packages-exp/functions-exp/src/service.test.ts
@@ -64,5 +64,22 @@ 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'
+      );
+    });
   });
 });
diff --git a/packages-exp/functions-exp/src/service.ts b/packages-exp/functions-exp/src/service.ts
index f51b838a0e0..e5c8c059a9b 100644
--- a/packages-exp/functions-exp/src/service.ts
+++ b/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 = 'us-central1';
+    } catch (e) {
+      this.customDomain = null;
+      this.region = DEFAULT_REGION;
+    }
   }
 
   _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}`;
   }
 }
 
diff --git a/packages-exp/functions-types-exp/index.d.ts b/packages-exp/functions-types-exp/index.d.ts
index e528fef46b7..9b529870825 100644
--- a/packages-exp/functions-types-exp/index.d.ts
+++ b/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;
 }
 
 /**
diff --git a/packages/functions/src/api/service.ts b/packages/functions/src/api/service.ts
index c59aacce0fd..44b6a0cce30 100644
--- a/packages/functions/src/api/service.ts
+++ b/packages/functions/src/api/service.ts
@@ -87,7 +87,7 @@ export class Service implements FirebaseFunctions, FirebaseService {
   private cancelAllRequests: Promise<void>;
   private deleteService!: () => void;
   private region: string;
-  private customDomain: string | null = null;
+  private customDomain: string | null;
 
   /**
    * Creates a new Functions service for the given app and (optional) region or custom domain.
@@ -117,6 +117,7 @@ export class Service implements FirebaseFunctions, FirebaseService {
       this.customDomain = url.origin;
       this.region = 'us-central1';
     } catch (e) {
+      this.customDomain = null;
       this.region = regionOrCustomDomain_;
     }
   }
@@ -137,17 +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}`;
     }
 
     if (this.customDomain !== null) {
       return `${this.customDomain}/${name}`;
     }
 
-    return `https://${region}-${projectId}.cloudfunctions.net/${name}`;
+    return `https://${this.region}-${projectId}.cloudfunctions.net/${name}`;
   }
 
   /**
diff --git a/packages/functions/test/service.test.ts b/packages/functions/test/service.test.ts
index 93224a3440f..324edec6f16 100644
--- a/packages/functions/test/service.test.ts
+++ b/packages/functions/test/service.test.ts
@@ -40,45 +40,37 @@ describe('Firebase Functions > Service', () => {
         'http://localhost:5005/my-project/us-central1/foo'
       );
     });
+  });
+
+  describe('custom region/domain constructor', () => {
+    const app: any = {
+      options: {
+        projectId: 'my-project'
+      }
+    };
 
     it('can use custom region', () => {
-      const customRegionService = createTestService(app, 'us-west2');     
+      const service = createTestService(app, 'my-region');
       assert.equal(
-        customRegionService._url('foo'),
-        'https://us-west2-my-project.cloudfunctions.net/foo'
+        service._url('foo'),
+        'https://my-region-my-project.cloudfunctions.net/foo'
       );
     });
 
     it('can use custom domain', () => {
-      const customDomainService = createTestService(app, 'https://mydomain.com');
+      const service = createTestService(app, 'https://mydomain.com');
       assert.equal(
-        customDomainService._url('foo'),
+        service._url('foo'),
         'https://mydomain.com/foo'
       );
     });
 
     it('prefers emulator to custom domain', () => {
-      const customDomainService = createTestService(app, 'https://mydomain.com');
-      customDomainService.useFunctionsEmulator('http://localhost:5005');
-      assert.equal(
-        customDomainService._url('foo'),
-        'http://localhost:5005/my-project/us-central1/foo'
-      );
-    });
-  });
-
-  describe('custom region constructor', () => {
-    const app: any = {
-      options: {
-        projectId: 'my-project'
-      }
-    };
-    const service = createTestService(app, 'my-region');
-
-    it('has valid urls', () => {
+      const service = createTestService(app, 'https://mydomain.com');
+      service.useFunctionsEmulator('http://localhost:5005');
       assert.equal(
         service._url('foo'),
-        'https://my-region-my-project.cloudfunctions.net/foo'
+        'http://localhost:5005/my-project/us-central1/foo'
       );
     });
   });

From 4df34d973b27ac9fbb1e9c6ff09d9d9e206ac4e9 Mon Sep 17 00:00:00 2001
From: Sam <samstern@google.com>
Date: Thu, 24 Sep 2020 13:01:10 +0100
Subject: [PATCH 3/5] Prettier

---
 packages-exp/functions-exp/src/service.test.ts |  5 +----
 packages/functions/src/config.ts               | 13 +++++++++++--
 packages/functions/test/service.test.ts        |  5 +----
 3 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/packages-exp/functions-exp/src/service.test.ts b/packages-exp/functions-exp/src/service.test.ts
index 42b8e9eeb67..9f518d29284 100644
--- a/packages-exp/functions-exp/src/service.test.ts
+++ b/packages-exp/functions-exp/src/service.test.ts
@@ -67,10 +67,7 @@ describe('Firebase Functions > Service', () => {
 
     it('correctly sets custom domain', () => {
       service = createTestService(app, 'https://mydomain.com');
-      assert.equal(
-        service._url('foo'),
-        'https://mydomain.com/foo'
-      );
+      assert.equal(service._url('foo'), 'https://mydomain.com/foo');
     });
 
     it('prefers emulator to custom domain', () => {
diff --git a/packages/functions/src/config.ts b/packages/functions/src/config.ts
index dd5f6ae88b6..df833a072ba 100644
--- a/packages/functions/src/config.ts
+++ b/packages/functions/src/config.ts
@@ -37,14 +37,23 @@ export function registerFunctions(
     Functions: Service
   };
 
-  function factory(container: ComponentContainer, regionOrCustomDomain?: 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, regionOrCustomDomain, fetchImpl);
+    return new Service(
+      app,
+      authProvider,
+      messagingProvider,
+      regionOrCustomDomain,
+      fetchImpl
+    );
   }
   instance.INTERNAL.registerComponent(
     new Component(FUNCTIONS_TYPE, factory, ComponentType.PUBLIC)
diff --git a/packages/functions/test/service.test.ts b/packages/functions/test/service.test.ts
index 324edec6f16..d91d1b683b8 100644
--- a/packages/functions/test/service.test.ts
+++ b/packages/functions/test/service.test.ts
@@ -59,10 +59,7 @@ describe('Firebase Functions > Service', () => {
 
     it('can use custom domain', () => {
       const service = createTestService(app, 'https://mydomain.com');
-      assert.equal(
-        service._url('foo'),
-        'https://mydomain.com/foo'
-      );
+      assert.equal(service._url('foo'), 'https://mydomain.com/foo');
     });
 
     it('prefers emulator to custom domain', () => {

From f61ba5aa1f899c20ac5aabdcf9611d23ce93a058 Mon Sep 17 00:00:00 2001
From: Sam <samstern@google.com>
Date: Thu, 24 Sep 2020 13:02:09 +0100
Subject: [PATCH 4/5] Add changeset

---
 .changeset/poor-eagles-think.md | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 .changeset/poor-eagles-think.md

diff --git a/.changeset/poor-eagles-think.md b/.changeset/poor-eagles-think.md
new file mode 100644
index 00000000000..9035b59e803
--- /dev/null
+++ b/.changeset/poor-eagles-think.md
@@ -0,0 +1,5 @@
+---
+'@firebase/functions': minor
+---
+
+Allow setting a custom domain for callable Cloud Functions.

From 05e6e0aa4508e943949890a1f9d04fc1d7d4eee4 Mon Sep 17 00:00:00 2001
From: Sam <samstern@google.com>
Date: Fri, 25 Sep 2020 10:53:46 +0100
Subject: [PATCH 5/5] Code review

---
 packages-exp/functions-exp/src/service.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages-exp/functions-exp/src/service.ts b/packages-exp/functions-exp/src/service.ts
index e5c8c059a9b..30c557761a5 100644
--- a/packages-exp/functions-exp/src/service.ts
+++ b/packages-exp/functions-exp/src/service.ts
@@ -101,10 +101,10 @@ export class FunctionsService implements _FirebaseService {
     try {
       const url = new URL(regionOrCustomDomain);
       this.customDomain = url.origin;
-      this.region = 'us-central1';
+      this.region = DEFAULT_REGION;
     } catch (e) {
       this.customDomain = null;
-      this.region = DEFAULT_REGION;
+      this.region = regionOrCustomDomain;
     }
   }