feat: add common sign-in resolver for simple email-to-email matching

- `providers.google.resolvers.emailMatchingUserEntityEmail()`
- `providers.microsoft.resolvers.emailMatchingUserEntityEmail()`
- `providers.okta.resolvers.emailMatchingUserEntityEmail()`

Signed-off-by: Patrick Jungermann <Patrick.Jungermann@gmail.com>

.changeset/strong-mangos-sell.md

@@ -2,7 +2,15 @@
 '@backstage/plugin-auth-backend': patch
 ---
 
-Add common signIn resolver to more providers.
+Add more common predefined sign-in resolvers to auth providers.
+
+Add the existing resolver to more providers (already available at `google`):
 
 - `providers.microsoft.resolvers.emailLocalPartMatchingUserEntityName()`
 - `providers.okta.resolvers.emailLocalPartMatchingUserEntityName()`
+
+Add a new resolver for simple email-to-email matching:
+
+- `providers.google.resolvers.emailMatchingUserEntityEmail()`
+- `providers.microsoft.resolvers.emailMatchingUserEntityEmail()`
+- `providers.okta.resolvers.emailMatchingUserEntityEmail()`

plugins/auth-backend/api-report.md

@@ -872,6 +872,7 @@ export const providers: Readonly<{
     ) => AuthProviderFactory;
     resolvers: Readonly<{
       emailLocalPartMatchingUserEntityName: () => SignInResolver<unknown>;
+      emailMatchingUserEntityEmail: () => SignInResolver<unknown>;
       emailMatchingUserEntityAnnotation(): SignInResolver<OAuthResult>;
     }>;
   }>;
@@ -890,6 +891,7 @@ export const providers: Readonly<{
     ) => AuthProviderFactory;
     resolvers: Readonly<{
       emailLocalPartMatchingUserEntityName: () => SignInResolver<unknown>;
+      emailMatchingUserEntityEmail: () => SignInResolver<unknown>;
       emailMatchingUserEntityAnnotation(): SignInResolver<OAuthResult>;
     }>;
   }>;
@@ -947,6 +949,7 @@ export const providers: Readonly<{
     ) => AuthProviderFactory;
     resolvers: Readonly<{
       emailLocalPartMatchingUserEntityName: () => SignInResolver<unknown>;
+      emailMatchingUserEntityEmail: () => SignInResolver<unknown>;
       emailMatchingUserEntityAnnotation(): SignInResolver<OAuthResult>;
     }>;
   }>;

plugins/auth-backend/src/providers/google/provider.ts

@@ -43,7 +43,10 @@ import {
   SignInResolver,
 } from '../types';
 import { createAuthProviderIntegration } from '../createAuthProviderIntegration';
-import { commonByEmailLocalPartResolver } from '../resolvers';
+import {
+  commonByEmailLocalPartResolver,
+  commonByEmailResolver,
+} from '../resolvers';
 
 type PrivateInfo = {
   refreshToken: string;
@@ -248,6 +251,10 @@ export const google = createAuthProviderIntegration({
      * Looks up the user by matching their email local part to the entity name.
      */
     emailLocalPartMatchingUserEntityName: () => commonByEmailLocalPartResolver,
+    /**
+     * Looks up the user by matching their email to the entity email.
+     */
+    emailMatchingUserEntityEmail: () => commonByEmailResolver,
     /**
      * Looks up the user by matching their email to the `google.com/email` annotation.
      */

plugins/auth-backend/src/providers/microsoft/provider.ts

@@ -43,7 +43,10 @@ import {
   AuthResolverContext,
 } from '../types';
 import { createAuthProviderIntegration } from '../createAuthProviderIntegration';
-import { commonByEmailLocalPartResolver } from '../resolvers';
+import {
+  commonByEmailLocalPartResolver,
+  commonByEmailResolver,
+} from '../resolvers';
 import { Logger } from 'winston';
 import fetch from 'node-fetch';
 
@@ -275,6 +278,10 @@ export const microsoft = createAuthProviderIntegration({
      * Looks up the user by matching their email local part to the entity name.
      */
     emailLocalPartMatchingUserEntityName: () => commonByEmailLocalPartResolver,
+    /**
+     * Looks up the user by matching their email to the entity email.
+     */
+    emailMatchingUserEntityEmail: () => commonByEmailResolver,
     /**
      * Looks up the user by matching their email to the `microsoft.com/email` annotation.
      */

plugins/auth-backend/src/providers/okta/provider.ts

@@ -43,7 +43,10 @@ import {
   AuthResolverContext,
 } from '../types';
 import { createAuthProviderIntegration } from '../createAuthProviderIntegration';
-import { commonByEmailLocalPartResolver } from '../resolvers';
+import {
+  commonByEmailLocalPartResolver,
+  commonByEmailResolver,
+} from '../resolvers';
 import { StateStore } from 'passport-oauth2';
 
 type PrivateInfo = {
@@ -279,6 +282,10 @@ export const okta = createAuthProviderIntegration({
      * Looks up the user by matching their email local part to the entity name.
      */
     emailLocalPartMatchingUserEntityName: () => commonByEmailLocalPartResolver,
+    /**
+     * Looks up the user by matching their email to the entity email.
+     */
+    emailMatchingUserEntityEmail: () => commonByEmailResolver,
     /**
      * Looks up the user by matching their email to the `okta.com/email` annotation.
      */

plugins/auth-backend/src/providers/resolvers.ts

@@ -35,3 +35,24 @@ export const commonByEmailLocalPartResolver: SignInResolver<unknown> = async (
     entityRef: { name: localPart },
   });
 };
+
+/**
+ * A common sign-in resolver that looks up the user using their email address
+ * as email of the entity.
+ */
+export const commonByEmailResolver: SignInResolver<unknown> = async (
+  info,
+  ctx,
+) => {
+  const { profile } = info;
+
+  if (!profile.email) {
+    throw new Error('Login failed, user profile does not contain an email');
+  }
+
+  return ctx.signInWithCatalogUser({
+    filter: {
+      'spec.profile.email': profile.email,
+    },
+  });
+};