config-loader: use multiple config roots

packages/backend-common/src/config.ts

@@ -23,7 +23,7 @@ import { loadConfig } from '@backstage/config-loader';
 export async function loadBackendConfig() {
   const paths = findPaths(__dirname);
   const configs = await loadConfig({
-    rootPath: paths.targetRoot,
+    rootPaths: [paths.targetDir, paths.targetRoot],
     shouldReadSecrets: true,
   });
   return configs;

packages/cli/src/commands/app/build.ts

@@ -21,7 +21,9 @@ import { paths } from '../../lib/paths';
 import { buildBundle } from '../../lib/bundler';
 
 export default async (cmd: Command) => {
-  const appConfigs = await loadConfig({ rootPath: paths.targetRoot });
+  const appConfigs = await loadConfig({
+    rootPaths: [paths.targetDir, paths.targetRoot],
+  });
   await buildBundle({
     entry: 'src/index',
     statsJsonEnabled: cmd.stats,

packages/cli/src/commands/app/serve.ts

@@ -21,7 +21,9 @@ import { paths } from '../../lib/paths';
 import { serveBundle } from '../../lib/bundler';
 
 export default async (cmd: Command) => {
-  const appConfigs = await loadConfig({ rootPath: paths.targetRoot });
+  const appConfigs = await loadConfig({
+    rootPaths: [paths.targetDir, paths.targetRoot],
+  });
   const waitForExit = await serveBundle({
     entry: 'src/index',
     checksEnabled: cmd.check,

packages/cli/src/commands/backend/dev.ts

@@ -21,7 +21,9 @@ import { paths } from '../../lib/paths';
 import { serveBackend } from '../../lib/bundler/backend';
 
 export default async (cmd: Command) => {
-  const appConfigs = await loadConfig({ rootPath: paths.targetRoot });
+  const appConfigs = await loadConfig({
+    rootPaths: [paths.targetDir, paths.targetRoot],
+  });
   const waitForExit = await serveBackend({
     entry: 'src/index',
     checksEnabled: cmd.check,

packages/cli/src/commands/plugin/export.ts

@@ -21,7 +21,9 @@ import { paths } from '../../lib/paths';
 import { buildBundle } from '../../lib/bundler';
 
 export default async (cmd: Command) => {
-  const appConfigs = await loadConfig({ rootPath: paths.targetRoot });
+  const appConfigs = await loadConfig({
+    rootPaths: [paths.targetDir, paths.targetRoot],
+  });
   await buildBundle({
     entry: 'dev/index',
     statsJsonEnabled: cmd.stats,

packages/cli/src/commands/plugin/serve.ts

@@ -21,7 +21,9 @@ import { paths } from '../../lib/paths';
 import { serveBundle } from '../../lib/bundler';
 
 export default async (cmd: Command) => {
-  const appConfigs = await loadConfig({ rootPath: paths.targetRoot });
+  const appConfigs = await loadConfig({
+    rootPaths: [paths.targetDir, paths.targetRoot],
+  });
   const waitForExit = await serveBundle({
     entry: 'dev/index',
     checksEnabled: cmd.check,

packages/config-loader/src/lib/resolver.ts

@@ -15,10 +15,11 @@
  */
 
 import { resolve as resolvePath } from 'path';
+import { pathExists } from 'fs-extra';
 
 type ResolveOptions = {
-  // Root path for search for app-config.yaml
-  rootPath: string;
+  // Root paths to search for config files. Config from earlier paths has higher priority.
+  rootPaths: string[];
 };
 
 /**
@@ -29,7 +30,14 @@ export async function resolveStaticConfig(
 ): Promise<string[]> {
   // TODO: We'll want this to be a bit more elaborate, probably adding configs for
   //       specific env, and maybe local config for plugins.
-  const configPath = resolvePath(options.rootPath, 'app-config.yaml');
+  const resolvedPaths = [];
 
-  return [configPath];
+  for (const rootPath of options.rootPaths) {
+    const path = resolvePath(rootPath, 'app-config.yaml');
+    if (await pathExists(path)) {
+      resolvedPaths.push(path);
+    }
+  }
+
+  return resolvedPaths;
 }

packages/config-loader/src/loader.ts

@@ -25,8 +25,8 @@ import {
 } from './lib';
 
 export type LoadConfigOptions = {
-  // Root path for search for app-config.yaml
-  rootPath: string;
+  // Root paths to search for config files. Config from earlier paths has higher priority.
+  rootPaths: string[];
 
   // Whether to read secrets or omit them, defaults to false.
   shouldReadSecrets?: boolean;