Expose types to handle Database management

This implements several types to own and manage databases on a database
server. The current SimpleDatabase* classes preserve the present
behaviour; future implementations can segregate databases to be owned by
different roles.

packages/backend/src/index.ts

@@ -24,17 +24,17 @@
 
 import Router from 'express-promise-router';
 import {
-  ensureDatabaseExists,
-  createDatabaseClient,
   createServiceBuilder,
   loadBackendConfig,
   getRootLogger,
   useHotMemoize,
   notFoundHandler,
+  SingleDatabaseConfiguration,
+  SingleDatabaseManager,
   SingleHostDiscovery,
   UrlReaders,
 } from '@backstage/backend-common';
-import { ConfigReader, AppConfig } from '@backstage/config';
+import { ConfigReader } from '@backstage/config';
 import healthcheck from './plugins/healthcheck';
 import auth from './plugins/auth';
 import catalog from './plugins/catalog';
@@ -48,37 +48,29 @@ import graphql from './plugins/graphql';
 import app from './plugins/app';
 import { PluginEnvironment } from './types';
 
-function makeCreateEnv(loadedConfigs: AppConfig[]) {
-  const config = ConfigReader.fromConfigs(loadedConfigs);
+function makeCreateEnv(config: ConfigReader) {
   const root = getRootLogger();
   const reader = UrlReaders.default({ logger: root, config });
   const discovery = SingleHostDiscovery.fromConfig(config);
 
   root.info(`Created UrlReader ${reader}`);
 
+  const databaseConfig = new SingleDatabaseConfiguration(
+    config.getConfig('backend.database'),
+  );
+  const databaseManager = new SingleDatabaseManager(databaseConfig);
+
   return (plugin: string): PluginEnvironment => {
     const logger = root.child({ type: 'plugin', plugin });
-    const database = createDatabaseClient(
-      config.getConfig('backend.database'),
-      {
-        connection: {
-          database: `backstage_plugin_${plugin}`,
-        },
-      },
-    );
-    return { logger, database, config, reader, discovery };
+    const databaseFactory = databaseManager.getDatabaseFactory(plugin);
+    return { logger, database: databaseFactory, config, reader, discovery };
   };
 }
 
 async function main() {
   const configs = await loadBackendConfig();
   const configReader = ConfigReader.fromConfigs(configs);
-  const createEnv = makeCreateEnv(configs);
-  await ensureDatabaseExists(
-    configReader.getConfig('backend.database'),
-    'backstage_plugin_catalog',
-    'backstage_plugin_auth',
-  );
+  const createEnv = makeCreateEnv(configReader);
 
   const healthcheckEnv = useHotMemoize(module, () => createEnv('healthcheck'));
   const catalogEnv = useHotMemoize(module, () => createEnv('catalog'));

packages/backend/src/plugins/catalog.ts

@@ -34,7 +34,10 @@ export default async function createPlugin({
 }: PluginEnvironment) {
   const locationReader = new LocationReaders({ logger, reader, config });
 
-  const db = await DatabaseManager.createDatabase(database, { logger });
+  const db = await DatabaseManager.createDatabase(
+    await database.getDatabase(),
+    { logger },
+  );
   const entitiesCatalog = new DatabaseEntitiesCatalog(db);
   const locationsCatalog = new DatabaseLocationsCatalog(db);
   const higherOrderOperation = new HigherOrderOperations(

packages/backend/src/types.ts

@@ -14,14 +14,17 @@
  * limitations under the License.
  */
 
-import Knex from 'knex';
 import { Logger } from 'winston';
 import { Config } from '@backstage/config';
-import { PluginEndpointDiscovery, UrlReader } from '@backstage/backend-common';
+import {
+  PluginDatabaseFactory,
+  PluginEndpointDiscovery,
+  UrlReader
+} from '@backstage/backend-common';
 
 export type PluginEnvironment = {
   logger: Logger;
-  database: Knex;
+  database: PluginDatabaseFactory;
   config: Config;
   reader: UrlReader;
   discovery: PluginEndpointDiscovery;