Merge pull request #12484 from backstage/mob/backend-system

Alpha Backend Framework 🚀
2022-07-08 16:20:09 +02:00
parent 1f5bb6cdbf 79849709d5
commit 125ad5ef66
67 changed files with 2215 additions and 2 deletions
@@ -0,0 +1 @@
+module.exports = require('@backstage/cli/config/eslint-factory')(__dirname);
@@ -0,0 +1,19 @@
+# @backstage/backend-app-api
+
+**This package is HIGHLY EXPERIMENTAL, do not use this for production**
+
+This package provides the core API used by Backstage backend apps.
+
+## Installation
+
+Add the library to your backend app package:
+
+```bash
+# From your Backstage root directory
+yarn add --cwd packages/backend @backstage/backend-app-api
+```
+
+## Documentation
+
+- [Backstage Readme](https://github.com/backstage/backstage/blob/master/README.md)
+- [Backstage Documentation](https://github.com/backstage/backstage/blob/master/docs/README.md)
@@ -0,0 +1,25 @@
+## API Report File for "@backstage/backend-app-api"
+
+> Do not edit this file. It is a report generated by [API Extractor](https://api-extractor.com/).
+
+```ts
+import { AnyServiceFactory } from '@backstage/backend-plugin-api';
+import { BackendRegistrable } from '@backstage/backend-plugin-api';
+
+// @public (undocumented)
+export interface Backend {
+  // (undocumented)
+  add(extension: BackendRegistrable): void;
+  // (undocumented)
+  start(): Promise<void>;
+}
+
+// @public (undocumented)
+export function createBackend(options?: CreateBackendOptions): Backend;
+
+// @public (undocumented)
+export interface CreateBackendOptions {
+  // (undocumented)
+  apis: AnyServiceFactory[];
+}
+```
@@ -0,0 +1,52 @@
+{
+  "name": "@backstage/backend-app-api",
+  "description": "Core API used by Backstage backend apps",
+  "version": "0.0.0",
+  "main": "src/index.ts",
+  "types": "src/index.ts",
+  "private": false,
+  "publishConfig": {
+    "access": "public",
+    "main": "dist/index.cjs.js",
+    "types": "dist/index.d.ts",
+    "alphaTypes": "dist/index.alpha.d.ts"
+  },
+  "backstage": {
+    "role": "node-library"
+  },
+  "homepage": "https://backstage.io",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/backstage/backstage",
+    "directory": "packages/backend-app-api"
+  },
+  "keywords": [
+    "backstage"
+  ],
+  "license": "Apache-2.0",
+  "scripts": {
+    "build": "backstage-cli package build --experimental-type-build",
+    "lint": "backstage-cli package lint",
+    "test": "backstage-cli package test",
+    "prepack": "backstage-cli package prepack",
+    "postpack": "backstage-cli package postpack",
+    "clean": "backstage-cli package clean",
+    "start": "backstage-cli package start"
+  },
+  "dependencies": {
+    "@backstage/backend-plugin-api": "^0.0.0",
+    "@backstage/backend-common": "^0.14.1-next.2",
+    "@backstage/backend-tasks": "^0.3.3-next.2",
+    "@backstage/plugin-permission-node": "^0.6.3-next.1",
+    "express": "^4.17.1",
+    "express-promise-router": "^4.1.0",
+    "winston": "^3.2.1"
+  },
+  "devDependencies": {
+    "@backstage/cli": "^0.18.0-next.2"
+  },
+  "files": [
+    "dist",
+    "alpha"
+  ]
+}
@@ -0,0 +1,23 @@
+/*
+ * 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.
+ */
+
+/**
+ * Core API used by Backstage backend apps.
+ *
+ * @packageDocumentation
+ */
+
+export * from './wiring';
@@ -0,0 +1,37 @@
+/*
+ * Copyright 2022 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 { CacheManager } from '@backstage/backend-common';
+import {
+  configServiceRef,
+  createServiceFactory,
+  cacheServiceRef,
+} from '@backstage/backend-plugin-api';
+
+// TODO: Work out some naming and implementation patterns for these
+export const cacheFactory = createServiceFactory({
+  service: cacheServiceRef,
+  deps: {
+    configFactory: configServiceRef,
+  },
+  factory: async ({ configFactory }) => {
+    const config = await configFactory('root');
+    const cacheManager = CacheManager.fromConfig(config);
+    return async (pluginId: string) => {
+      return cacheManager.forPlugin(pluginId);
+    };
+  },
+});
@@ -0,0 +1,40 @@
+/*
+ * Copyright 2022 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 { loadBackendConfig } from '@backstage/backend-common';
+import {
+  configServiceRef,
+  createServiceFactory,
+  loggerToWinstonLogger,
+  loggerServiceRef,
+} from '@backstage/backend-plugin-api';
+
+export const configFactory = createServiceFactory({
+  service: configServiceRef,
+  deps: {
+    loggerFactory: loggerServiceRef,
+  },
+  factory: async ({ loggerFactory }) => {
+    const logger = await loggerFactory('root');
+    const config = await loadBackendConfig({
+      argv: process.argv,
+      logger: loggerToWinstonLogger(logger),
+    });
+    return async () => {
+      return config;
+    };
+  },
+});
@@ -0,0 +1,36 @@
+/*
+ * Copyright 2022 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 { DatabaseManager } from '@backstage/backend-common';
+import {
+  configServiceRef,
+  createServiceFactory,
+  databaseServiceRef,
+} from '@backstage/backend-plugin-api';
+
+export const databaseFactory = createServiceFactory({
+  service: databaseServiceRef,
+  deps: {
+    configFactory: configServiceRef,
+  },
+  factory: async ({ configFactory }) => {
+    const config = await configFactory('root');
+    const databaseManager = DatabaseManager.fromConfig(config);
+    return async (pluginId: string) => {
+      return databaseManager.forPlugin(pluginId);
+    };
+  },
+});
@@ -0,0 +1,36 @@
+/*
+ * Copyright 2022 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 { SingleHostDiscovery } from '@backstage/backend-common';
+import {
+  configServiceRef,
+  createServiceFactory,
+  discoveryServiceRef,
+} from '@backstage/backend-plugin-api';
+
+export const discoveryFactory = createServiceFactory({
+  service: discoveryServiceRef,
+  deps: {
+    configFactory: configServiceRef,
+  },
+  factory: async ({ configFactory }) => {
+    const config = await configFactory('root');
+    const discovery = SingleHostDiscovery.fromConfig(config);
+    return async () => {
+      return discovery;
+    };
+  },
+});
@@ -0,0 +1,49 @@
+/*
+ * Copyright 2022 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 {
+  createServiceFactory,
+  httpRouterServiceRef,
+  configServiceRef,
+} from '@backstage/backend-plugin-api';
+import Router from 'express-promise-router';
+import { Handler } from 'express';
+import { createServiceBuilder } from '@backstage/backend-common';
+
+export const httpRouterFactory = createServiceFactory({
+  service: httpRouterServiceRef,
+  deps: {
+    configFactory: configServiceRef,
+  },
+  factory: async ({ configFactory }) => {
+    const rootRouter = Router();
+
+    const service = createServiceBuilder(module)
+      .loadConfig(await configFactory('root'))
+      .addRouter('', rootRouter);
+
+    await service.start();
+
+    return async (pluginId?: string) => {
+      const path = pluginId ? `/api/${pluginId}` : '';
+      return {
+        use(handler: Handler) {
+          rootRouter.use(path, handler);
+        },
+      };
+    };
+  },
+});
@@ -0,0 +1,39 @@
+/*
+ * Copyright 2022 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 { cacheFactory } from './cacheService';
+import { configFactory } from './configService';
+import { databaseFactory } from './databaseService';
+import { discoveryFactory } from './discoveryService';
+import { loggerFactory } from './loggerService';
+import { permissionsFactory } from './permissionsService';
+import { schedulerFactory } from './schedulerService';
+import { tokenManagerFactory } from './tokenManagerService';
+import { urlReaderFactory } from './urlReaderService';
+import { httpRouterFactory } from './httpRouterService';
+
+export const defaultServiceFactories = [
+  cacheFactory,
+  configFactory,
+  databaseFactory,
+  discoveryFactory,
+  loggerFactory,
+  permissionsFactory,
+  schedulerFactory,
+  tokenManagerFactory,
+  urlReaderFactory,
+  httpRouterFactory,
+];
@@ -0,0 +1,50 @@
+/*
+ * Copyright 2022 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 { createRootLogger } from '@backstage/backend-common';
+import {
+  createServiceFactory,
+  Logger,
+  loggerServiceRef,
+} from '@backstage/backend-plugin-api';
+import { Logger as WinstonLogger } from 'winston';
+
+class BackstageLogger implements Logger {
+  static fromWinston(logger: WinstonLogger): BackstageLogger {
+    return new BackstageLogger(logger);
+  }
+
+  private constructor(private readonly winston: WinstonLogger) {}
+
+  info(message: string, ...meta: any[]): void {
+    this.winston.info(message, ...meta);
+  }
+
+  child(fields: { [name: string]: string }): Logger {
+    return new BackstageLogger(this.winston.child(fields));
+  }
+}
+
+export const loggerFactory = createServiceFactory({
+  service: loggerServiceRef,
+  deps: {},
+  factory: async () => {
+    const root = BackstageLogger.fromWinston(createRootLogger());
+    return async (pluginId: string) => {
+      return root.child({ pluginId });
+    };
+  },
+});
@@ -0,0 +1,45 @@
+/*
+ * Copyright 2022 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 {
+  configServiceRef,
+  createServiceFactory,
+  discoveryServiceRef,
+  permissionsServiceRef,
+  tokenManagerServiceRef,
+} from '@backstage/backend-plugin-api';
+import { ServerPermissionClient } from '@backstage/plugin-permission-node';
+
+export const permissionsFactory = createServiceFactory({
+  service: permissionsServiceRef,
+  deps: {
+    configFactory: configServiceRef,
+    discoveryFactory: discoveryServiceRef,
+    tokenManagerFactory: tokenManagerServiceRef,
+  },
+  factory: async ({ configFactory, discoveryFactory, tokenManagerFactory }) => {
+    const config = await configFactory('root');
+    const discovery = await discoveryFactory('root');
+    const tokenManager = await tokenManagerFactory('root');
+    const permissions = ServerPermissionClient.fromConfig(config, {
+      discovery,
+      tokenManager,
+    });
+    return async (_pluginId: string) => {
+      return permissions;
+    };
+  },
+});
@@ -0,0 +1,36 @@
+/*
+ * Copyright 2022 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 {
+  configServiceRef,
+  createServiceFactory,
+  schedulerServiceRef,
+} from '@backstage/backend-plugin-api';
+import { TaskScheduler } from '@backstage/backend-tasks';
+
+export const schedulerFactory = createServiceFactory({
+  service: schedulerServiceRef,
+  deps: {
+    configFactory: configServiceRef,
+  },
+  factory: async ({ configFactory }) => {
+    const config = await configFactory('root');
+    const taskScheduler = TaskScheduler.fromConfig(config);
+    return async (pluginId: string) => {
+      return taskScheduler.forPlugin(pluginId);
+    };
+  },
+});
@@ -0,0 +1,60 @@
+/*
+ * Copyright 2022 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 {
+  configServiceRef,
+  loggerServiceRef,
+  createServiceFactory,
+  tokenManagerServiceRef,
+  loggerToWinstonLogger,
+} from '@backstage/backend-plugin-api';
+import { ServerTokenManager } from '@backstage/backend-common';
+
+export const tokenManagerFactory = createServiceFactory({
+  service: tokenManagerServiceRef,
+  deps: {
+    configFactory: configServiceRef,
+    loggerFactory: loggerServiceRef,
+  },
+  factory: async ({ configFactory, loggerFactory }) => {
+    const logger = await loggerFactory('root');
+    const config = await configFactory('root');
+    return async (_pluginId: string) => {
+      // doesn't the logger want to be inferred from the plugin tho here?
+      // maybe ... also why do we recreate it every time otherwise
+      // we should memoize on a per plugin right? so I think it's should be fine to re-use the plugin one
+      // we shouldn't recreate on a per plugin basis.
+      // hm - on the other hand, is this really ever called more than once?
+      // not this function right. should only be called when the plugin requests this serviceRef
+      // yeah so no need to worry about memo probably
+      // but we still want to scope the logger to the ServrTokenmanagfer>?
+      // mm sure maybe
+      // maybe in this case it doesn't provide so much value b
+      // oh hang on - isn't it up to THE MANAGER to make a child internally if it wants to do that
+      // so that it becomes a property intrinsic to that class, no matter how it's constructed
+      // or is that too much responsibility for it - making the constructor complex so to speak, making it harder to tweak that behavior
+      // this is not ultra efficient :)
+
+      // I think the naming here is wrong to be gonest
+      // this isn't like the cache manager or the database manager
+      // the manager name is confusuion i think
+      // aye perhaps
+      return ServerTokenManager.fromConfig(config, {
+        logger: loggerToWinstonLogger(logger),
+      });
+    };
+  },
+});
@@ -0,0 +1,41 @@
+/*
+ * Copyright 2022 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 { UrlReaders } from '@backstage/backend-common';
+import {
+  configServiceRef,
+  createServiceFactory,
+  loggerServiceRef,
+  loggerToWinstonLogger,
+  urlReaderServiceRef,
+} from '@backstage/backend-plugin-api';
+
+export const urlReaderFactory = createServiceFactory({
+  service: urlReaderServiceRef,
+  deps: {
+    configFactory: configServiceRef,
+    loggerFactory: loggerServiceRef,
+  },
+  factory: async ({ configFactory, loggerFactory }) => {
+    return async (pluginId: string) => {
+      const logger = await loggerFactory(pluginId);
+      return UrlReaders.default({
+        logger: loggerToWinstonLogger(logger),
+        config: await configFactory(pluginId),
+      });
+    };
+  },
+});
@@ -0,0 +1,155 @@
+/*
+ * Copyright 2022 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 {
+  BackendRegistrable,
+  ExtensionPoint,
+  ServiceRef,
+} from '@backstage/backend-plugin-api';
+import { BackendRegisterInit, ServiceHolder } from './types';
+
+type ServiceOrExtensionPoint = ExtensionPoint<unknown> | ServiceRef<unknown>;
+
+export class BackendInitializer {
+  #started = false;
+  #extensions = new Map<BackendRegistrable, unknown>();
+  #registerInits = new Array<BackendRegisterInit>();
+  #extensionPoints = new Map<ServiceOrExtensionPoint, unknown>();
+  #serviceHolder: ServiceHolder;
+
+  constructor(serviceHolder: ServiceHolder) {
+    this.#serviceHolder = serviceHolder;
+  }
+
+  async #getInitDeps(
+    deps: { [name: string]: ServiceOrExtensionPoint },
+    pluginId: string,
+  ) {
+    return Object.fromEntries(
+      await Promise.all(
+        Object.entries(deps).map(async ([name, ref]) => [
+          name,
+          this.#extensionPoints.get(ref) ||
+            (await this.#serviceHolder.get(ref as ServiceRef<unknown>)!(
+              pluginId,
+            )),
+        ]),
+      ),
+    );
+  }
+
+  add<TOptions>(extension: BackendRegistrable, options?: TOptions) {
+    if (this.#started) {
+      throw new Error(
+        'extension can not be added after the backend has started',
+      );
+    }
+    this.#extensions.set(extension, options);
+  }
+
+  async start(): Promise<void> {
+    console.log(`Starting backend`);
+    if (this.#started) {
+      throw new Error('Backend has already started');
+    }
+    this.#started = true;
+
+    for (const [extension] of this.#extensions) {
+      const provides = new Set<ServiceRef<unknown>>();
+
+      let registerInit: BackendRegisterInit | undefined = undefined;
+
+      console.log('Registering', extension.id);
+      extension.register({
+        registerExtensionPoint: (extensionPointRef, impl) => {
+          if (registerInit) {
+            throw new Error('registerExtensionPoint called after registerInit');
+          }
+          if (this.#extensionPoints.has(extensionPointRef)) {
+            throw new Error(`API ${extensionPointRef.id} already registered`);
+          }
+          this.#extensionPoints.set(extensionPointRef, impl);
+          provides.add(extensionPointRef);
+        },
+        registerInit: registerOptions => {
+          if (registerInit) {
+            throw new Error('registerInit must only be called once');
+          }
+          registerInit = {
+            id: extension.id,
+            provides,
+            consumes: new Set(Object.values(registerOptions.deps)),
+            deps: registerOptions.deps,
+            init: registerOptions.init as BackendRegisterInit['init'],
+          };
+        },
+      });
+
+      if (!registerInit) {
+        throw new Error(
+          `registerInit was not called by register in ${extension.id}`,
+        );
+      }
+
+      this.#registerInits.push(registerInit);
+    }
+
+    this.validateSetup();
+
+    const orderedRegisterResults = this.#resolveInitOrder(this.#registerInits);
+
+    for (const registerInit of orderedRegisterResults) {
+      const deps = await this.#getInitDeps(registerInit.deps, registerInit.id);
+      await registerInit.init(deps);
+    }
+  }
+
+  private validateSetup() {}
+
+  #resolveInitOrder(registerInits: Array<BackendRegisterInit>) {
+    let registerInitsToOrder = registerInits.slice();
+    const orderedRegisterInits = new Array<BackendRegisterInit>();
+
+    // TODO: Validate duplicates
+
+    while (registerInitsToOrder.length > 0) {
+      const toRemove = new Set<unknown>();
+
+      for (const registerInit of registerInitsToOrder) {
+        const unInitializedDependents = [];
+
+        for (const serviceRef of registerInit.provides) {
+          if (
+            registerInitsToOrder.some(
+              init => init !== registerInit && init.consumes.has(serviceRef),
+            )
+          ) {
+            unInitializedDependents.push(serviceRef);
+          }
+        }
+
+        if (unInitializedDependents.length === 0) {
+          console.log(`DEBUG: pushed ${registerInit.id} to results`);
+          orderedRegisterInits.push(registerInit);
+          toRemove.add(registerInit);
+        }
+      }
+
+      registerInitsToOrder = registerInitsToOrder.filter(r => !toRemove.has(r));
+    }
+    return orderedRegisterInits;
+  }
+}
@@ -0,0 +1,45 @@
+/*
+ * Copyright 2022 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 {
+  AnyServiceFactory,
+  BackendRegistrable,
+} from '@backstage/backend-plugin-api';
+import { BackendInitializer } from './BackendInitializer';
+import { ServiceRegistry } from './ServiceRegistry';
+import { Backend } from './types';
+
+export class BackstageBackend implements Backend {
+  #services: ServiceRegistry;
+  #initializer: BackendInitializer;
+
+  constructor(apiFactories: AnyServiceFactory[]) {
+    this.#services = new ServiceRegistry(apiFactories);
+    this.#initializer = new BackendInitializer(this.#services);
+  }
+
+  add(extension: BackendRegistrable): void {
+    this.#initializer.add(extension);
+  }
+
+  async start(): Promise<void> {
+    await this.#initializer.start();
+  }
+
+  // async stop(): Promise<void> {
+  //   await this.#initializer.stop();
+  // }
+}
@@ -0,0 +1,63 @@
+/*
+ * Copyright 2022 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 {
+  AnyServiceFactory,
+  FactoryFunc,
+  ServiceRef,
+} from '@backstage/backend-plugin-api';
+
+export class ServiceRegistry {
+  readonly #implementations: Map<string, Map<string, unknown>>;
+  readonly #factories: Map<string, AnyServiceFactory>;
+
+  constructor(factories: AnyServiceFactory[]) {
+    this.#factories = new Map(factories.map(f => [f.service.id, f]));
+    this.#implementations = new Map();
+  }
+
+  get<T>(ref: ServiceRef<T>): FactoryFunc<T> | undefined {
+    const factory = this.#factories.get(ref.id);
+    if (!factory) {
+      return undefined;
+    }
+
+    return async (pluginId: string): Promise<T> => {
+      let implementations = this.#implementations.get(ref.id);
+      if (implementations) {
+        if (implementations.has(pluginId)) {
+          return implementations.get(pluginId) as T;
+        }
+      } else {
+        implementations = new Map();
+        this.#implementations.set(ref.id, implementations);
+      }
+
+      const factoryDeps = Object.fromEntries(
+        Object.entries(factory.deps).map(([name, serviceRef]) => [
+          name,
+          this.get(serviceRef)!, // TODO: throw
+        ]),
+      );
+
+      const factoryFunc = await factory.factory(factoryDeps);
+      const implementation = await factoryFunc(pluginId);
+
+      implementations.set(pluginId, implementation);
+
+      return implementation as T;
+    };
+  }
+}
@@ -0,0 +1,18 @@
+/*
+ * Copyright 2022 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 type { Backend, CreateBackendOptions } from './types';
+export { createBackend } from './types';
@@ -0,0 +1,62 @@
+/*
+ * Copyright 2022 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 {
+  AnyServiceFactory,
+  BackendRegistrable,
+  FactoryFunc,
+  ServiceRef,
+} from '@backstage/backend-plugin-api';
+import { defaultServiceFactories } from '../services/implementations';
+import { BackstageBackend } from './BackstageBackend';
+
+/**
+ * @public
+ */
+export interface Backend {
+  add(extension: BackendRegistrable): void;
+  start(): Promise<void>;
+}
+
+export interface BackendRegisterInit {
+  id: string;
+  consumes: Set<ServiceRef<unknown>>;
+  provides: Set<ServiceRef<unknown>>;
+  deps: { [name: string]: ServiceRef<unknown> };
+  init: (deps: { [name: string]: unknown }) => Promise<void>;
+}
+
+/**
+ * @public
+ */
+export interface CreateBackendOptions {
+  apis: AnyServiceFactory[];
+}
+
+export type ServiceHolder = {
+  get<T>(api: ServiceRef<T>): FactoryFunc<T> | undefined;
+};
+
+/**
+ * @public
+ */
+export function createBackend(options?: CreateBackendOptions): Backend {
+  // TODO: merge with provided APIs
+  return new BackstageBackend([
+    ...defaultServiceFactories,
+    ...(options?.apis ?? []),
+  ]);
+}
@@ -0,0 +1 @@
+module.exports = require('@backstage/cli/config/eslint-factory')(__dirname);
@@ -0,0 +1,5 @@
+# example-backend-next
+
+This is an example backend for the new **EXPERIMENTAL** Backstage backend system.
+
+Do not use this in your own projects.
@@ -0,0 +1,38 @@
+{
+  "name": "example-backend-next",
+  "version": "0.0.0",
+  "main": "dist/index.cjs.js",
+  "types": "src/index.ts",
+  "license": "Apache-2.0",
+  "private": true,
+  "backstage": {
+    "role": "backend"
+  },
+  "homepage": "https://backstage.io",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/backstage/backstage",
+    "directory": "packages/backend-next"
+  },
+  "keywords": [
+    "backstage"
+  ],
+  "scripts": {
+    "start": "backstage-cli package start",
+    "build": "backstage-cli package build",
+    "lint": "backstage-cli package lint",
+    "test": "backstage-cli package test",
+    "clean": "backstage-cli package clean"
+  },
+  "dependencies": {
+    "@backstage/backend-app-api": "^0.0.0",
+    "@backstage/plugin-catalog-backend": "^1.2.1-next.2",
+    "@backstage/plugin-scaffolder-backend": "^1.4.0-next.2"
+  },
+  "devDependencies": {
+    "@backstage/cli": "^0.18.0-next.2"
+  },
+  "files": [
+    "dist"
+  ]
+}
@@ -0,0 +1,27 @@
+/*
+ * Copyright 2022 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 { createBackend } from '@backstage/backend-app-api';
+import { catalogPlugin } from '@backstage/plugin-catalog-backend';
+import { scaffolderCatalogModule } from '@backstage/plugin-scaffolder-backend';
+
+const backend = createBackend({
+  apis: [],
+});
+
+backend.add(catalogPlugin({}));
+backend.add(scaffolderCatalogModule({}));
+backend.start();
@@ -0,0 +1 @@
+module.exports = require('@backstage/cli/config/eslint-factory')(__dirname);
@@ -0,0 +1,19 @@
+# @backstage/backend-plugin-api
+
+**This package is HIGHLY EXPERIMENTAL, do not use this for production**
+
+This package provides the core API used by Backstage backend plugins.
+
+## Installation
+
+Add the library to your backend plugin package:
+
+```bash
+# From your Backstage root directory
+yarn add --cwd plugin/<plugin>-backend @backstage/backend-plugin-api
+```
+
+## Documentation
+
+- [Backstage Readme](https://github.com/backstage/backstage/blob/master/README.md)
+- [Backstage Documentation](https://github.com/backstage/backstage/blob/master/docs/README.md)
@@ -0,0 +1,197 @@
+## API Report File for "@backstage/backend-plugin-api"
+
+> Do not edit this file. It is a report generated by [API Extractor](https://api-extractor.com/).
+
+```ts
+import { Config } from '@backstage/config';
+import { Handler } from 'express';
+import { Logger as Logger_2 } from 'winston';
+import { PermissionAuthorizer } from '@backstage/plugin-permission-common';
+import { PermissionEvaluator } from '@backstage/plugin-permission-common';
+import { PluginCacheManager } from '@backstage/backend-common';
+import { PluginDatabaseManager } from '@backstage/backend-common';
+import { PluginEndpointDiscovery } from '@backstage/backend-common';
+import { PluginTaskScheduler } from '@backstage/backend-tasks';
+import { TokenManager } from '@backstage/backend-common';
+import { TransportStreamOptions } from 'winston-transport';
+import { UrlReader } from '@backstage/backend-common';
+
+// @public (undocumented)
+export type AnyServiceFactory = ServiceFactory<
+  unknown,
+  unknown,
+  {
+    [key in string]: unknown;
+  }
+>;
+
+// @public (undocumented)
+export interface BackendInitRegistry {
+  // (undocumented)
+  registerExtensionPoint<TExtensionPoint>(
+    ref: ServiceRef<TExtensionPoint>,
+    impl: TExtensionPoint,
+  ): void;
+  // (undocumented)
+  registerInit<
+    Deps extends {
+      [name in string]: unknown;
+    },
+  >(options: {
+    deps: {
+      [name in keyof Deps]: ServiceRef<Deps[name]>;
+    };
+    init: (deps: Deps) => Promise<void>;
+  }): void;
+}
+
+// @public (undocumented)
+export interface BackendModuleConfig<TOptions> {
+  // (undocumented)
+  moduleId: string;
+  // (undocumented)
+  pluginId: string;
+  // (undocumented)
+  register(
+    reg: Omit<BackendInitRegistry, 'registerExtensionPoint'>,
+    options: TOptions,
+  ): void;
+}
+
+// @public (undocumented)
+export interface BackendPluginConfig<TOptions> {
+  // (undocumented)
+  id: string;
+  // (undocumented)
+  register(reg: BackendInitRegistry, options: TOptions): void;
+}
+
+// @public (undocumented)
+export interface BackendRegistrable {
+  // (undocumented)
+  id: string;
+  // (undocumented)
+  register(reg: BackendInitRegistry): void;
+}
+
+// @public (undocumented)
+export const cacheServiceRef: ServiceRef<PluginCacheManager>;
+
+// @public (undocumented)
+export const configServiceRef: ServiceRef<Config>;
+
+// @public (undocumented)
+export function createBackendModule<TOptions>(
+  config: BackendModuleConfig<TOptions>,
+): (option: TOptions) => BackendRegistrable;
+
+// @public (undocumented)
+export function createBackendPlugin<TOptions>(
+  config: BackendPluginConfig<TOptions>,
+): (option: TOptions) => BackendRegistrable;
+
+// @public (undocumented)
+export function createExtensionPoint<T>(options: {
+  id: string;
+}): ExtensionPoint<T>;
+
+// @public (undocumented)
+export function createServiceFactory<
+  Api,
+  Impl extends Api,
+  Deps extends {
+    [name in string]: unknown;
+  },
+>(factory: ServiceFactory<Api, Impl, Deps>): ServiceFactory<Api, Api, {}>;
+
+// @public (undocumented)
+export function createServiceRef<T>(options: { id: string }): ServiceRef<T>;
+
+// @public (undocumented)
+export const databaseServiceRef: ServiceRef<PluginDatabaseManager>;
+
+// @public (undocumented)
+export type DepsToDepFactories<T> = {
+  [key in keyof T]: (pluginId: string) => Promise<T[key]>;
+};
+
+// @public (undocumented)
+export const discoveryServiceRef: ServiceRef<PluginEndpointDiscovery>;
+
+// @public
+export type ExtensionPoint<T> = {
+  id: string;
+  T: T;
+  toString(): string;
+  $$ref: 'extension-point';
+};
+
+// @public (undocumented)
+export type FactoryFunc<Impl> = (pluginId: string) => Promise<Impl>;
+
+// @public (undocumented)
+export interface HttpRouterService {
+  // (undocumented)
+  use(handler: Handler): void;
+}
+
+// @public (undocumented)
+export const httpRouterServiceRef: ServiceRef<HttpRouterService>;
+
+// @public (undocumented)
+export interface Logger {
+  // (undocumented)
+  child(fields: { [name: string]: string }): Logger;
+  // (undocumented)
+  info(message: string): void;
+}
+
+// @public (undocumented)
+export const loggerServiceRef: ServiceRef<Logger>;
+
+// @public (undocumented)
+export function loggerToWinstonLogger(
+  logger: Logger,
+  opts?: TransportStreamOptions,
+): Logger_2;
+
+// @public (undocumented)
+export const permissionsServiceRef: ServiceRef<
+  PermissionAuthorizer | PermissionEvaluator
+>;
+
+// @public (undocumented)
+export const schedulerServiceRef: ServiceRef<PluginTaskScheduler>;
+
+// @public (undocumented)
+export type ServiceFactory<
+  TApi,
+  TImpl extends TApi,
+  TDeps extends {
+    [name in string]: unknown;
+  },
+> = {
+  service: ServiceRef<TApi>;
+  deps: TypesToServiceRef<TDeps>;
+  factory(deps: DepsToDepFactories<TDeps>): Promise<FactoryFunc<TImpl>>;
+};
+
+// @public
+export type ServiceRef<T> = {
+  id: string;
+  T: T;
+  toString(): string;
+  $$ref: 'service';
+};
+
+// @public (undocumented)
+export const tokenManagerServiceRef: ServiceRef<TokenManager>;
+
+// @public (undocumented)
+export type TypesToServiceRef<T> = {
+  [key in keyof T]: ServiceRef<T[key]>;
+};
+
+// @public (undocumented)
+export const urlReaderServiceRef: ServiceRef<UrlReader>;
+```
@@ -0,0 +1,53 @@
+{
+  "name": "@backstage/backend-plugin-api",
+  "description": "Core API used by Backstage backend plugins",
+  "version": "0.0.0",
+  "main": "src/index.ts",
+  "types": "src/index.ts",
+  "private": false,
+  "publishConfig": {
+    "access": "public",
+    "main": "dist/index.cjs.js",
+    "types": "dist/index.d.ts",
+    "alphaTypes": "dist/index.alpha.d.ts"
+  },
+  "backstage": {
+    "role": "node-library"
+  },
+  "homepage": "https://backstage.io",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/backstage/backstage",
+    "directory": "packages/backend-plugin-api"
+  },
+  "keywords": [
+    "backstage"
+  ],
+  "license": "Apache-2.0",
+  "scripts": {
+    "build": "backstage-cli package build --experimental-type-build",
+    "lint": "backstage-cli package lint",
+    "test": "backstage-cli package test",
+    "prepack": "backstage-cli package prepack",
+    "postpack": "backstage-cli package postpack",
+    "clean": "backstage-cli package clean",
+    "start": "backstage-cli package start"
+  },
+  "dependencies": {
+    "@backstage/config": "^1.0.1",
+    "@backstage/backend-common": "^0.14.1-next.2",
+    "@backstage/plugin-permission-common": "^0.6.3-next.0",
+    "@backstage/backend-tasks": "^0.3.3-next.2",
+    "@types/express": "^4.17.6",
+    "express": "^4.17.1",
+    "winston": "^3.2.1",
+    "winston-transport": "^4.5.0"
+  },
+  "devDependencies": {
+    "@backstage/cli": "^0.18.0-next.2"
+  },
+  "files": [
+    "dist",
+    "alpha"
+  ]
+}
@@ -0,0 +1,24 @@
+/*
+ * 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.
+ */
+
+/**
+ * Core API used by Backstage backend plugins.
+ *
+ * @packageDocumentation
+ */
+
+export * from './services';
+export * from './wiring';
@@ -0,0 +1,25 @@
+/*
+ * Copyright 2022 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 { createServiceRef } from '../system/types';
+import { PluginCacheManager } from '@backstage/backend-common';
+
+/**
+ * @public
+ */
+export const cacheServiceRef = createServiceRef<PluginCacheManager>({
+  id: 'core.cache',
+});
@@ -0,0 +1,25 @@
+/*
+ * Copyright 2022 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 { createServiceRef } from '../system/types';
+
+/**
+ * @public
+ */
+export const configServiceRef = createServiceRef<Config>({
+  id: 'core.config',
+});
@@ -0,0 +1,25 @@
+/*
+ * Copyright 2022 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 { PluginDatabaseManager } from '@backstage/backend-common';
+import { createServiceRef } from '../system/types';
+
+/**
+ * @public
+ */
+export const databaseServiceRef = createServiceRef<PluginDatabaseManager>({
+  id: 'core.database',
+});
@@ -0,0 +1,25 @@
+/*
+ * Copyright 2022 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 { createServiceRef } from '../system/types';
+import { PluginEndpointDiscovery } from '@backstage/backend-common';
+
+/**
+ * @public
+ */
+export const discoveryServiceRef = createServiceRef<PluginEndpointDiscovery>({
+  id: 'core.discovery',
+});
@@ -0,0 +1,32 @@
+/*
+ * Copyright 2022 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 { createServiceRef } from '../system/types';
+import { Handler } from 'express';
+
+/**
+ * @public
+ */
+export interface HttpRouterService {
+  use(handler: Handler): void;
+}
+
+/**
+ * @public
+ */
+export const httpRouterServiceRef = createServiceRef<HttpRouterService>({
+  id: 'core.httpRouter',
+});
@@ -0,0 +1,28 @@
+/*
+ * Copyright 2022 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 { configServiceRef } from './configServiceRef';
+export { httpRouterServiceRef } from './httpRouterServiceRef';
+export type { HttpRouterService } from './httpRouterServiceRef';
+export { loggerServiceRef } from './loggerServiceRef';
+export type { Logger } from './loggerServiceRef';
+export { urlReaderServiceRef } from './urlReaderServiceRef';
+export { cacheServiceRef } from './cacheServiceRef';
+export { databaseServiceRef } from './databaseServiceRef';
+export { discoveryServiceRef } from './discoveryServiceRef';
+export { tokenManagerServiceRef } from './tokenManagerServiceRef';
+export { permissionsServiceRef } from './permissionsServiceRef';
+export { schedulerServiceRef } from './schedulerServiceRef';
@@ -0,0 +1,32 @@
+/*
+ * Copyright 2022 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 { createServiceRef } from '../system/types';
+
+/**
+ * @public
+ */
+export interface Logger {
+  info(message: string): void;
+  child(fields: { [name: string]: string }): Logger;
+}
+
+/**
+ * @public
+ */
+export const loggerServiceRef = createServiceRef<Logger>({
+  id: 'core.logger',
+});
@@ -0,0 +1,30 @@
+/*
+ * Copyright 2022 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 { createServiceRef } from '../system/types';
+import {
+  PermissionAuthorizer,
+  PermissionEvaluator,
+} from '@backstage/plugin-permission-common';
+
+/**
+ * @public
+ */
+export const permissionsServiceRef = createServiceRef<
+  PermissionEvaluator | PermissionAuthorizer
+>({
+  id: 'core.permissions',
+});
@@ -0,0 +1,25 @@
+/*
+ * Copyright 2022 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 { createServiceRef } from '../system/types';
+import { PluginTaskScheduler } from '@backstage/backend-tasks';
+
+/**
+ * @public
+ */
+export const schedulerServiceRef = createServiceRef<PluginTaskScheduler>({
+  id: 'core.scheduler',
+});
@@ -0,0 +1,25 @@
+/*
+ * Copyright 2022 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 { createServiceRef } from '../system/types';
+import { TokenManager } from '@backstage/backend-common';
+
+/**
+ * @public
+ */
+export const tokenManagerServiceRef = createServiceRef<TokenManager>({
+  id: 'core.tokenManager',
+});
@@ -0,0 +1,25 @@
+/*
+ * Copyright 2022 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 { createServiceRef } from '../system/types';
+import { UrlReader } from '@backstage/backend-common';
+
+/**
+ * @public
+ */
+export const urlReaderServiceRef = createServiceRef<UrlReader>({
+  id: 'core.urlReader',
+});
@@ -0,0 +1,17 @@
+/*
+ * Copyright 2022 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 { loggerToWinstonLogger } from './loggerToWinstonLogger';
@@ -0,0 +1,44 @@
+/*
+ * Copyright 2022 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 { Logger as BackstageLogger } from '../definitions';
+import { Logger as WinstonLogger, createLogger } from 'winston';
+import Transport, { TransportStreamOptions } from 'winston-transport';
+
+class BackstageLoggerTransport extends Transport {
+  constructor(
+    private readonly backstageLogger: BackstageLogger,
+    opts?: TransportStreamOptions,
+  ) {
+    super(opts);
+  }
+
+  log(info: { message: string }, callback: VoidFunction) {
+    // TODO: add support for levels and fields
+    this.backstageLogger.info(info.message);
+    callback();
+  }
+}
+
+/** @public */
+export function loggerToWinstonLogger(
+  logger: BackstageLogger,
+  opts?: TransportStreamOptions,
+): WinstonLogger {
+  return createLogger({
+    transports: [new BackstageLoggerTransport(logger, opts)],
+  });
+}
@@ -0,0 +1,19 @@
+/*
+ * Copyright 2022 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 * from './definitions';
+export * from './helpers';
+export * from './system';
@@ -0,0 +1,25 @@
+/*
+ * Copyright 2022 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 type {
+  ServiceRef,
+  TypesToServiceRef,
+  DepsToDepFactories,
+  FactoryFunc,
+  ServiceFactory,
+  AnyServiceFactory,
+} from './types';
+export { createServiceRef, createServiceFactory } from './types';
@@ -0,0 +1,90 @@
+/*
+ * Copyright 2022 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.
+ */
+
+/**
+ * TODO
+ *
+ * @public
+ */
+export type ServiceRef<T> = {
+  id: string;
+
+  /**
+   * Utility for getting the type of the service, using `typeof serviceRef.T`.
+   * Attempting to actually read this value will result in an exception.
+   */
+  T: T;
+
+  toString(): string;
+
+  $$ref: 'service';
+};
+
+/** @public */
+export type TypesToServiceRef<T> = { [key in keyof T]: ServiceRef<T[key]> };
+
+/** @public */
+export type DepsToDepFactories<T> = {
+  [key in keyof T]: (pluginId: string) => Promise<T[key]>;
+};
+
+/** @public */
+export type FactoryFunc<Impl> = (pluginId: string) => Promise<Impl>;
+
+/** @public */
+export type ServiceFactory<
+  TApi,
+  TImpl extends TApi,
+  TDeps extends { [name in string]: unknown },
+> = {
+  service: ServiceRef<TApi>;
+  deps: TypesToServiceRef<TDeps>;
+  factory(deps: DepsToDepFactories<TDeps>): Promise<FactoryFunc<TImpl>>;
+};
+
+/** @public */
+export type AnyServiceFactory = ServiceFactory<
+  unknown,
+  unknown,
+  { [key in string]: unknown }
+>;
+
+/**
+ * @public
+ */
+export function createServiceRef<T>(options: { id: string }): ServiceRef<T> {
+  return {
+    id: options.id,
+    get T(): T {
+      throw new Error(`tried to read ServiceRef.T of ${this}`);
+    },
+    toString() {
+      return `serviceRef{${options.id}}`;
+    },
+    $$ref: 'service', // TODO: declare
+  };
+}
+
+/**
+ * @public
+ */
+export function createServiceFactory<
+  Api,
+  Impl extends Api,
+  Deps extends { [name in string]: unknown },
+>(factory: ServiceFactory<Api, Impl, Deps>): ServiceFactory<Api, Api, {}> {
+  return factory;
+}
@@ -0,0 +1,18 @@
+/*
+ * Copyright 2022 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 type { BackendRegistrable } from './types';
+export * from './types';
@@ -0,0 +1,113 @@
+/*
+ * Copyright 2022 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 { ServiceRef } from '../services/system/types';
+
+/**
+ * TODO
+ *
+ * @public
+ */
+export type ExtensionPoint<T> = {
+  id: string;
+
+  /**
+   * Utility for getting the type of the extension point, using `typeof extensionPoint.T`.
+   * Attempting to actually read this value will result in an exception.
+   */
+  T: T;
+
+  toString(): string;
+
+  $$ref: 'extension-point';
+};
+
+/** @public */
+export function createExtensionPoint<T>(options: {
+  id: string;
+}): ExtensionPoint<T> {
+  return {
+    id: options.id,
+    get T(): T {
+      throw new Error(`tried to read ExtensionPoint.T of ${this}`);
+    },
+    toString() {
+      return `extensionPoint{${options.id}}`;
+    },
+    $$ref: 'extension-point', // TODO: declare
+  };
+}
+
+/** @public */
+export interface BackendInitRegistry {
+  registerExtensionPoint<TExtensionPoint>(
+    ref: ServiceRef<TExtensionPoint>,
+    impl: TExtensionPoint,
+  ): void;
+  registerInit<Deps extends { [name in string]: unknown }>(options: {
+    deps: { [name in keyof Deps]: ServiceRef<Deps[name]> };
+    init: (deps: Deps) => Promise<void>;
+  }): void;
+}
+
+/** @public */
+export interface BackendRegistrable {
+  id: string;
+  register(reg: BackendInitRegistry): void;
+}
+
+/** @public */
+export interface BackendPluginConfig<TOptions> {
+  id: string;
+  register(reg: BackendInitRegistry, options: TOptions): void;
+}
+
+// TODO: Make option optional in the returned factory if they are indeed optional
+/** @public */
+export function createBackendPlugin<TOptions>(
+  config: BackendPluginConfig<TOptions>,
+): (option: TOptions) => BackendRegistrable {
+  return options => ({
+    id: config.id,
+    register(register) {
+      return config.register(register, options);
+    },
+  });
+}
+
+/** @public */
+export interface BackendModuleConfig<TOptions> {
+  pluginId: string;
+  moduleId: string;
+  register(
+    reg: Omit<BackendInitRegistry, 'registerExtensionPoint'>,
+    options: TOptions,
+  ): void;
+}
+
+// TODO: Make option optional in the returned factory if they are indeed optional
+/** @public */
+export function createBackendModule<TOptions>(
+  config: BackendModuleConfig<TOptions>,
+): (option: TOptions) => BackendRegistrable {
+  return options => ({
+    id: `${config.pluginId}.${config.moduleId}`,
+    register(register) {
+      // TODO: Hide registerExtensionPoint
+      return config.register(register, options);
+    },
+  });
+}
				`@@ -0,0 +1 @@`
				`module.exports = require('@backstage/cli/config/eslint-factory')(__dirname);`