cli: experimental support for using embedded-postgres as dev DB

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

packages/cli-module-build/package.json

@@ -65,6 +65,7 @@
     "cross-spawn": "^7.0.3",
     "css-loader": "^6.5.1",
     "ctrlc-windows": "^2.1.0",
+    "embedded-postgres": "^17.2.0-beta.15",
     "esbuild-loader": "^4.0.0",
     "eslint-rspack-plugin": "^4.2.1",
     "eslint-webpack-plugin": "^4.2.0",
@@ -77,6 +78,7 @@
     "node-stdlib-browser": "^1.3.1",
     "npm-packlist": "^5.0.0",
     "p-queue": "^6.6.2",
+    "portfinder": "^1.0.32",
     "postcss": "^8.1.0",
     "postcss-import": "^16.1.0",
     "process": "^0.11.10",

packages/cli-module-build/src/lib/runner/runBackend.ts

@@ -24,6 +24,7 @@ import { isAbsolute as isAbsolutePath } from 'node:path';
 import { targetPaths } from '@backstage/cli-common';
 
 import spawn from 'cross-spawn';
+import { startEmbeddedDb } from './startEmbeddedDb';
 
 const loaderArgs = [
   '--enable-source-maps',
@@ -57,6 +58,16 @@ export async function runBackend(options: RunBackendOptions) {
   const server = new IpcServer();
   ServerDataStore.bind(server);
 
+  const extraEnv: Record<string, string> = {};
+
+  if (process.env.EXPERIMENTAL_DEV_DB) {
+    const db = await startEmbeddedDb();
+    extraEnv.APP_CONFIG_backend_database = JSON.stringify({
+      client: 'pg',
+      connection: db.connection,
+    });
+  }
+
   let exiting = false;
   let firstStart = true;
   let child: ChildProcess | undefined;
@@ -134,6 +145,7 @@ export async function runBackend(options: RunBackendOptions) {
         cwd: options.targetDir,
         env: {
           ...process.env,
+          ...extraEnv,
           BACKSTAGE_CLI_LINKED_WORKSPACE: options.linkedWorkspace,
           BACKSTAGE_CLI_CHANNEL: '1',
           ESBK_TSCONFIG_PATH: targetPaths.resolveRoot('tsconfig.json'),

packages/cli-module-build/src/lib/runner/startEmbeddedDb.ts

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2024 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 os from 'node:os';
+import fs from 'fs-extra';
+import { resolve as resolvePath } from 'path';
+import { getPortPromise } from 'portfinder';
+
+export async function startEmbeddedDb() {
+  const { default: EmbeddedPostgres } = await import('embedded-postgres').catch(
+    error => {
+      throw new Error(
+        `Failed to load peer dependency 'embedded-postgres' for generating SQL reports. ` +
+          `It must be installed as an explicit dependency in your project. Caused by; ${error}`,
+      );
+    },
+  );
+
+  const host = 'localhost';
+  const user = 'postgres';
+  const password = 'password';
+  const port = await getPortPromise();
+  const tmpDir = await fs.mkdtemp(
+    resolvePath(os.tmpdir(), 'backstage-dev-db-'),
+  );
+  const pg = new EmbeddedPostgres({
+    databaseDir: tmpDir,
+    user,
+    password,
+    port,
+    persistent: false,
+    onError(_messageOrError) {},
+    onLog(_message) {},
+  });
+
+  // Create the cluster config files
+  await pg.initialise();
+
+  // Start the server
+  await pg.start();
+
+  return {
+    connection: {
+      host,
+      user,
+      password,
+      port,
+    },
+    async close() {
+      await pg.stop();
+      await fs.rmdir(tmpDir, { recursive: true, maxRetries: 3 });
+    },
+  };
+}

packages/cli-module-build/src/types.d.ts

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2024 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.
+ */
+
+// It's missing a types entry point, but has types in dist
+declare module 'embedded-postgres' {
+  export { default } from 'embedded-postgres/dist/index';
+}