From ed4ee6fdfb5879e699e1d3bde3bc7f55ce81c857 Mon Sep 17 00:00:00 2001
From: Patrik Oldsberg <poldsberg@gmail.com>
Date: Wed, 15 Apr 2026 09:45:03 +0200
Subject: [PATCH] cli: fix config path resolution for embedded-postgres
 detection

Resolve config paths relative to the target package directory instead
of the workspace root in readDatabaseClient, matching the behavior of
the rest of the config loading system.

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
Made-with: Cursor
Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
Made-with: Cursor
---
 .../fix-embedded-postgres-config-paths.md     |  5 ++++
 .patches/pr-33914.txt                         |  1 +
 .../src/lib/runner/runBackend.test.ts         | 23 ++++++++++++++++++-
 .../src/lib/runner/runBackend.ts              |  9 ++++++--
 4 files changed, 35 insertions(+), 3 deletions(-)
 create mode 100644 .changeset/fix-embedded-postgres-config-paths.md
 create mode 100644 .patches/pr-33914.txt

diff --git a/.changeset/fix-embedded-postgres-config-paths.md b/.changeset/fix-embedded-postgres-config-paths.md
new file mode 100644
index 0000000000..7697636fb5
--- /dev/null
+++ b/.changeset/fix-embedded-postgres-config-paths.md
@@ -0,0 +1,5 @@
+---
+'@backstage/cli-module-build': patch
+---
+
+Fixed config path resolution for the embedded-postgres database client detection to resolve paths relative to the target package directory rather than the workspace root.
diff --git a/.patches/pr-33914.txt b/.patches/pr-33914.txt
new file mode 100644
index 0000000000..e9b94dde35
--- /dev/null
+++ b/.patches/pr-33914.txt
@@ -0,0 +1 @@
+Fix config path resolution for embedded-postgres detection in `repo start`
diff --git a/packages/cli-module-build/src/lib/runner/runBackend.test.ts b/packages/cli-module-build/src/lib/runner/runBackend.test.ts
index b6ac8fd54d..4f655b041c 100644
--- a/packages/cli-module-build/src/lib/runner/runBackend.test.ts
+++ b/packages/cli-module-build/src/lib/runner/runBackend.test.ts
@@ -50,10 +50,11 @@ jest.mock('ctrlc-windows', () => ({
 }));
 
 const mockToConfig = jest.fn();
+const mockConfigSourcesDefault = jest.fn().mockReturnValue({});
 
 jest.mock('@backstage/config-loader', () => ({
   ConfigSources: {
-    default: () => ({}),
+    default: (...args: any[]) => mockConfigSourcesDefault(...args),
     toConfig: (...args: any[]) => mockToConfig(...args),
   },
 }));
@@ -216,6 +217,26 @@ describe('runBackend', () => {
       });
     });
 
+    it('should resolve config paths relative to targetDir', async () => {
+      mockToConfig.mockResolvedValue({
+        close: jest.fn(),
+        getOptionalString: () => undefined,
+      });
+
+      runBackend({
+        entry: 'src/index',
+        targetDir: '/root/packages/backend',
+        configPaths: ['../../config/local.yaml'],
+      });
+      await jest.advanceTimersByTimeAsync(100);
+
+      expect(mockConfigSourcesDefault).toHaveBeenCalledWith(
+        expect.objectContaining({
+          argv: ['--config', '/root/config/local.yaml'],
+        }),
+      );
+    });
+
     it('should not start embedded DB for other database clients', async () => {
       mockToConfig.mockResolvedValue({
         close: jest.fn(),
diff --git a/packages/cli-module-build/src/lib/runner/runBackend.ts b/packages/cli-module-build/src/lib/runner/runBackend.ts
index 464ff10cec..95dd8784fd 100644
--- a/packages/cli-module-build/src/lib/runner/runBackend.ts
+++ b/packages/cli-module-build/src/lib/runner/runBackend.ts
@@ -68,7 +68,10 @@ export async function runBackend(options: RunBackendOptions) {
 
   let embeddedDb: Awaited<ReturnType<typeof startEmbeddedDb>> | undefined;
 
-  const dbClient = await readDatabaseClient(options.configPaths);
+  const dbClient = await readDatabaseClient(
+    options.configPaths,
+    options.targetDir,
+  );
   if (dbClient === 'embedded-postgres') {
     embeddedDb = await startEmbeddedDb();
     extraEnv.APP_CONFIG_backend_database = JSON.stringify({
@@ -220,14 +223,16 @@ export async function runBackend(options: RunBackendOptions) {
 
 async function readDatabaseClient(
   configPaths?: string[],
+  targetDir?: string,
 ): Promise<string | undefined> {
   const rootDir = targetPaths.rootDir;
+  const configBaseDir = targetDir ?? rootDir;
   const source = ConfigSources.default({
     rootDir,
     allowMissingDefaultConfig: true,
     argv: (configPaths ?? []).flatMap(p => [
       '--config',
-      isAbsolutePath(p) ? p : resolvePath(rootDir, p),
+      isAbsolutePath(p) ? p : resolvePath(configBaseDir, p),
     ]),
   });