auth-node: add proxy provider APIs

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

plugins/auth-node/src/index.ts

@@ -25,6 +25,7 @@ export * from './flow';
 export * from './identity';
 export * from './oauth';
 export * from './passport';
+export * from './proxy';
 export * from './sign-in';
 export type {
   AuthProviderConfig,

plugins/auth-node/src/proxy/createProxyAuthProviderFactory.ts

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2023 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import {
+  readDeclarativeSignInResolver,
+  SignInResolverFactory,
+} from '../sign-in';
+import {
+  AuthProviderFactory,
+  ProfileTransform,
+  SignInResolver,
+} from '../types';
+import { createProxyAuthRouteHandlers } from './createProxyRouteHandlers';
+import { ProxyAuthenticator } from './types';
+
+export function createProxyAuthProviderFactory<TResult>(options: {
+  authenticator: ProxyAuthenticator<unknown, TResult>;
+  profileTransform?: ProfileTransform<TResult>;
+  signInResolver?: SignInResolver<TResult>;
+  signInResolverFactories?: Record<
+    string,
+    SignInResolverFactory<TResult, unknown>
+  >;
+}): AuthProviderFactory {
+  return ctx => {
+    const signInResolver =
+      options.signInResolver ??
+      readDeclarativeSignInResolver({
+        config: ctx.config,
+        signInResolverFactories: options.signInResolverFactories ?? {},
+      });
+
+    if (!signInResolver) {
+      throw new Error(
+        `No sign-in resolver configured for proxy auth provider '${ctx.providerId}'`,
+      );
+    }
+
+    return createProxyAuthRouteHandlers<TResult>({
+      signInResolver,
+      config: ctx.config,
+      authenticator: options.authenticator,
+      resolverContext: ctx.resolverContext,
+      profileTransform: options.profileTransform,
+    });
+  };
+}

plugins/auth-node/src/proxy/createProxyRouteHandlers.ts

@@ -0,0 +1,79 @@
+/*
+ * Copyright 2020 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { Request, Response } from 'express';
+import { Config } from '@backstage/config';
+import {
+  AuthProviderRouteHandlers,
+  AuthResolverContext,
+  ClientAuthResponse,
+  ProfileTransform,
+  SignInResolver,
+} from '../types';
+import { ProxyAuthenticator } from './types';
+import { prepareBackstageIdentityResponse } from '../identity';
+
+/** @public */
+export interface ProxyAuthRouteHandlersOptions<TResult> {
+  authenticator: ProxyAuthenticator<any, TResult>;
+  config: Config;
+  resolverContext: AuthResolverContext;
+  signInResolver: SignInResolver<TResult>;
+  profileTransform?: ProfileTransform<TResult>;
+}
+
+/** @public */
+export function createProxyAuthRouteHandlers<TResult>(
+  options: ProxyAuthRouteHandlersOptions<TResult>,
+): AuthProviderRouteHandlers {
+  const { authenticator, config, resolverContext, signInResolver } = options;
+
+  const profileTransform =
+    options.profileTransform ?? authenticator.defaultProfileTransform;
+  const authenticatorCtx = authenticator.initialize({ config });
+
+  return {
+    async start(): Promise<void> {
+      throw new Error('Not implemented');
+    },
+
+    async frameHandler(): Promise<void> {
+      throw new Error('Not implemented');
+    },
+
+    async refresh(this: never, req: Request, res: Response): Promise<void> {
+      const { result } = await authenticator.authenticate(
+        { req },
+        authenticatorCtx,
+      );
+
+      const { profile } = await profileTransform(result, resolverContext);
+
+      const identity = await signInResolver(
+        { profile, result },
+        resolverContext,
+      );
+
+      const response: ClientAuthResponse<{}> = {
+        profile,
+        providerInfo: {},
+        backstageIdentity: prepareBackstageIdentityResponse(identity),
+      };
+
+      res.status(200).json(response);
+    },
+  };
+}

plugins/auth-node/src/proxy/index.ts

@@ -0,0 +1,22 @@
+/*
+ * Copyright 2023 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+export { createProxyAuthenticator, type ProxyAuthenticator } from './types';
+export { createProxyAuthProviderFactory } from './createProxyAuthProviderFactory';
+export {
+  createProxyAuthRouteHandlers,
+  type ProxyAuthRouteHandlersOptions,
+} from './createProxyRouteHandlers';

plugins/auth-node/src/proxy/types.ts

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2023 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { Config } from '@backstage/config';
+import { Request } from 'express';
+import { ProfileTransform } from '../types';
+
+export interface ProxyAuthenticator<TContext, TResult> {
+  defaultProfileTransform: ProfileTransform<TResult>;
+  initialize(ctx: { config: Config }): Promise<TContext>;
+  authenticate(
+    options: { req: Request },
+    ctx: TContext,
+  ): Promise<{ result: TResult }>;
+}
+
+export function createProxyAuthenticator<TContext, TResult>(
+  authenticator: ProxyAuthenticator<TContext, TResult>,
+): ProxyAuthenticator<TContext, TResult> {
+  return authenticator;
+}