Merge pull request #3538 from lowjoel/optional_npmrc

feat(cli): Support .npmrc when building distribution packages

.changeset/spotty-paws-think.md

@@ -0,0 +1,5 @@
+---
+'@backstage/cli': patch
+---
+
+Support `.npmrc` when building with private NPM registries

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

@@ -34,11 +34,15 @@ export default async (cmd: Command) => {
   const pkgPath = paths.resolveTarget(PKG_PATH);
   const pkg = await fs.readJson(pkgPath);
   const appConfigs = await findAppConfigs();
+  const npmrc = (await fs.pathExists(paths.resolveTargetRoot('.npmrc')))
+    ? ['.npmrc']
+    : [];
   const tempDistWorkspace = await createDistWorkspace([pkg.name], {
     buildDependencies: Boolean(cmd.build),
     files: [
       'package.json',
       'yarn.lock',
+      ...npmrc,
       ...appConfigs,
       { src: paths.resolveTarget('Dockerfile'), dest: 'Dockerfile' },
     ],

packages/cli/src/commands/index.ts

@@ -55,7 +55,11 @@ export function registerCommands(program: CommanderStatic) {
     .helpOption(', --backstage-cli-help') // Let docker handle --help
     .option('--build', 'Build packages before packing them into the image')
     .description(
-      'Bundles the package into a docker image. All extra args are forwarded to docker image build',
+      // TODO: Add example use cases in Backstage documentation.
+      // For example, if a $NPM_TOKEN needs to be exposed, run `backend:build-image --secret
+      // id=NPM_TOKEN,src=/NPM_TOKEN.txt`.
+      'Bundles the package into a docker image. All extra args are forwarded to ' +
+        '`docker image build`.',
     )
     .action(lazy(() => import('./backend/buildImage').then(m => m.default)));