using npm run commands for building angular application (supports pre steps).

Automatically embed the application version in the UI.

webapp/frontend/git.version.ts

@@ -0,0 +1,25 @@
+import { writeFileSync } from 'fs';
+import { dedent } from 'tslint/lib/utils';
+import { promisify } from 'util';
+import * as child from 'child_process';
+const exec = promisify(child.exec);
+
+async function createVersionsFile(filename: string) {
+    const tag = (await exec('git describe --tags')).stdout.toString().trim();
+    const revision = (await exec('git rev-parse --short HEAD')).stdout.toString().trim();
+    const branch = (await exec('git rev-parse --abbrev-ref HEAD')).stdout.toString().trim();
+
+    console.log(`version: '${process.env.npm_package_version}', revision: '${revision}', branch: '${branch}'`);
+
+    const content = dedent`
+      // this file is automatically generated by git.version.ts script
+      export const versions = {
+        version: '${tag}',
+        revision: '${revision}',
+        branch: '${branch}'
+      };`;
+
+    writeFileSync(filename, content, {encoding: 'utf8'});
+}
+
+createVersionsFile('src/environments/versions.ts');