Merge pull request #15559 from agentbellnorm/provide-embedded-app-bundle

[TechDocs] Allow user to provide embedded app bundle and specify port

packages/techdocs-cli/cli-report.md

@@ -100,6 +100,8 @@ Options:
   --no-docker
   --mkdocs-port <PORT>
   -v --verbose
+  --preview-app-bundle-path <PATH_TO_BUNDLE>
+  --preview-app-port <PORT>
   -h, --help
 ```
 

packages/techdocs-cli/src/commands/index.ts

@@ -18,6 +18,7 @@ import { Command } from 'commander';
 import { TechdocsGenerator } from '@backstage/plugin-techdocs-node';
 
 const defaultDockerImage = TechdocsGenerator.defaultDockerImage;
+const defaultPreviewAppPort = '3000';
 
 export function registerCommands(program: Command) {
   program
@@ -251,6 +252,25 @@ export function registerCommands(program: Command) {
     )
     .option('--mkdocs-port <PORT>', 'Port for MkDocs server to use', '8000')
     .option('-v --verbose', 'Enable verbose output.', false)
+    .option(
+      '--preview-app-bundle-path <PATH_TO_BUNDLE>',
+      'Preview documentation using another web app',
+    )
+    .option(
+      '--preview-app-port <PORT>',
+      'Port for the preview app to be served on',
+      defaultPreviewAppPort,
+    )
+    .hook('preAction', command => {
+      if (
+        command.opts().previewAppPort !== defaultPreviewAppPort &&
+        !command.opts().previewAppBundlePath
+      ) {
+        command.error(
+          '--preview-app-port can only be used together with --preview-app-bundle-path',
+        );
+      }
+    })
     .action(lazy(() => import('./serve/serve').then(m => m.default)));
 }
 

packages/techdocs-cli/src/commands/serve/serve.ts

@@ -42,6 +42,10 @@ function findPreviewBundlePath(): string {
   }
 }
 
+function getPreviewAppPath(opts: OptionValues): string {
+  return opts.previewAppBundlePath ?? findPreviewBundlePath();
+}
+
 export default async function serve(opts: OptionValues) {
   const logger = createLogger({ verbose: opts.verbose });
 
@@ -52,10 +56,6 @@ export default async function serve(opts: OptionValues) {
     ? true
     : false;
 
-  // TODO: Backstage app port should also be configurable as a CLI option. However, since we bundle
-  // a backstage app, we define app.baseUrl in the app-config.yaml.
-  // Hence, it is complicated to make this configurable.
-  const backstagePort = 3000;
   const backstageBackendPort = 7007;
 
   const mkdocsDockerAddr = `http://0.0.0.0:${opts.mkdocsPort}`;
@@ -115,9 +115,10 @@ export default async function serve(opts: OptionValues) {
     );
   }
 
-  const port = isDevMode ? backstageBackendPort : backstagePort;
+  const port = isDevMode ? backstageBackendPort : opts.previewAppPort;
+  const previewAppPath = getPreviewAppPath(opts);
   const httpServer = new HTTPServer(
-    findPreviewBundlePath(),
+    previewAppPath,
     port,
     opts.mkdocsPort,
     opts.verbose,