Merge pull request #2994 from spotify/rugvip/conflagrate

config-loader: switch to using --config options to load in config

packages/backend-common/package.json

@@ -46,6 +46,7 @@
     "knex": "^0.21.1",
     "lodash": "^4.17.15",
     "logform": "^2.1.1",
+    "minimist": "^1.2.5",
     "morgan": "^1.10.0",
     "prom-client": "^12.0.0",
     "selfsigned": "^1.10.7",
@@ -64,6 +65,7 @@
     "@backstage/cli": "^0.1.1-alpha.25",
     "@types/compression": "^1.7.0",
     "@types/http-errors": "^1.6.3",
+    "@types/minimist": "^1.2.0",
     "@types/morgan": "^1.9.0",
     "@types/stoppable": "^1.1.0",
     "@types/supertest": "^2.0.8",

packages/backend-common/src/config.ts

@@ -14,24 +14,32 @@
  * limitations under the License.
  */
 
+import { resolve as resolvePath } from 'path';
+import parseArgs from 'minimist';
+import { Logger } from 'winston';
 import { findPaths } from '@backstage/cli-common';
 import { Config, ConfigReader } from '@backstage/config';
 import { loadConfig } from '@backstage/config-loader';
-import { Logger } from 'winston';
 
 type Options = {
   logger: Logger;
+  // process.argv or any other overrides
+  argv: string[];
 };
 
 /**
  * Load configuration for a Backend
  */
 export async function loadBackendConfig(options: Options): Promise<Config> {
+  const args = parseArgs(options.argv);
+  const configOpts: string[] = [args.config ?? []].flat();
+
   /* eslint-disable-next-line no-restricted-syntax */
   const paths = findPaths(__dirname);
   const configs = await loadConfig({
     env: process.env.APP_ENV ?? process.env.NODE_ENV ?? 'development',
-    rootPaths: [paths.targetRoot, paths.targetDir],
+    configRoot: paths.targetRoot,
+    configPaths: configOpts.map(opt => resolvePath(opt)),
     shouldReadSecrets: true,
   });