build(bazel): improve remote caching for AIO local deps build

Fix non-hermetic zipping of example zips by fixing the zip entry timestamps.

I also hardcoded stamp values in stable-status.txt and volatile-status.txt using the workspace status command for the aio_local_deps config to improve cache performance. The Bazel remote cache appears to not ignore volatile-status.txt when there are no other changes, unlike the local Bazel cache:

bazelbuild/bazel#10075 (comment)

aio/BUILD.bazel

@@ -125,7 +125,6 @@ copy_to_directory(
 # All source and configuration files required to build the docs app
 APPLICATION_FILES = [
     "angular.json",
-    "package.json",
     "tsconfig.app.json",
     "tsconfig.json",
     "tsconfig.worker.json",

aio/scripts/local-workspace-status.mjs

@@ -16,7 +16,20 @@ const pkgJson = JSON.parse(fs.readFileSync(pkgJsonPath, 'utf8'));
 
 const aioAngularVersion = pkgJson.dependencies['@angular/core'].replace(/^[\^~]/, '') + "+forAIOLocalBuildToAvoidMismatch";
 
-// Output the workspace status variable format to stdout so Bazel can read it
 console.log(`\
 BUILD_SCM_VERSION ${aioAngularVersion}
 `);
+
+// Fix stable-status.txt values to improve remote cache performance.
+console.log(`\
+BUILD_HOST fake_host
+BUILD_USER fake_user
+`)
+
+// Fix the timestamp in volatile-status.txt to improve remote cache performance.
+// Unlike the local Bazel cache, the remote cache does not ignore volatile-status.txt
+// and will invalidate actions that depend on it when the values change.
+// https://github.com/bazelbuild/bazel/issues/10075#issuecomment-546872111
+console.log(`\
+BUILD_TIMESTAMP 0
+`)

aio/tools/example-zipper/exampleZipper.mjs

@@ -182,18 +182,25 @@ export class ExampleZipper {
       // zip.append(fs.createReadStream(fileName), { name: relativePath });
       let output = regionExtractor()(content, extn).contents;
 
-      zip.append(output, { name: relativePath } );
+      appendToZip(zip, output, { name: relativePath, date: "0"});
     });
 
     // also a systemjs config
     if (exampleType === 'systemjs') {
-      zip.append(fs.readFileSync(this.examplesSystemjsConfig, 'utf8'), { name: 'src/systemjs.config.js' });
-      zip.append(fs.readFileSync(this.examplesSystemjsLoaderConfig, 'utf8'), { name: 'src/systemjs-angular-loader.js' });
+      appendToZip(zip, fs.readFileSync(this.examplesSystemjsConfig, 'utf8'), { name: 'src/systemjs.config.js' });
+      appendToZip(zip, fs.readFileSync(this.examplesSystemjsLoaderConfig, 'utf8'), { name: 'src/systemjs-angular-loader.js' });
       // a modified tsconfig
       let tsconfig = fs.readFileSync(this.exampleTsconfig, 'utf8');
-      zip.append(this._changeTypeRoots(tsconfig), {name: 'src/tsconfig.json'});
+      appendToZip(zip, this._changeTypeRoots(tsconfig), {name: 'src/tsconfig.json' });
     }
 
     zip.finalize();
   }
 }
+
+// Fix the timestamp on zip entries in order create reproducible zip
+// files, which improves remote Bazel cache performance.
+function appendToZip(zip, source, data) {
+  const FIXED_DATE = new Date(0);
+  zip.append(source, {...data, date: FIXED_DATE});
+}