Integrate FAH Local Builds with Universal Maker by falahat · Pull Request #10382 · firebase/firebase-tools

falahat · 2026-04-17T17:55:32Z

Description

This takes the existing local builds solution and uses the Universal Maker binary (which runs all relevant buildpacks) instead of hackily running the apphosting adapter manually.

The Universal Maker is a more well-supported tool and behaves more similar to Cloud Builds so we can have more confidence about framework support and fidelity.

Major changes

Automatically downloads the universal maker when it's needed, verifying its hash
Calls the universal maker, correctly handling the .apphosting folder.
For now, this relies on the apphosting generated bundle.yaml file rather than UM's output.json, but that will be fixed later

Scenarios Tested

Created a local build with the

Sample Commands

firebase experiments:enable apphostinglocalbuilds
firebase experiments:enable universalMaker

firebase deploy

gemini-code-assist

Code Review

This pull request adds support for 'Universal Maker' local builds, integrates Secret Manager secret resolution for local environments, and refactors ABIU configuration. Key feedback includes fixing a blocking issue in the build watcher, adhering to style guides for YAML parsing and error handling, and optimizing the bundling process to avoid slow file copies of node_modules.

falahat · 2026-04-17T18:11:14Z

/gemini review

gemini-code-assist

Code Review

This pull request introduces the "Universal Maker" for App Hosting local builds, enabling standalone binary builds through a new experiment. It also enhances secret management by implementing a utility to resolve secrets from Secret Manager during local builds, adding a security confirmation prompt, and introducing the --allow-local-build-secrets flag. Furthermore, the PR removes explicit "Automatic Base Image Updates" (ABIU) configuration flags, integrating ABIU status into the runtime selection instead. Review feedback suggests strengthening test assertions for binary execution, removing unknown type assertions to comply with the style guide, and generalizing build artifact packaging logic to remove framework-specific assumptions.

falahat · 2026-04-17T20:26:33Z

/gemini review

gemini-code-assist

Code Review

This pull request introduces support for a new 'Universal Maker' standalone binary for local builds in App Hosting, controlled via an experimental flag. It adds the runUniversalMaker function to handle the binary execution, artifact management, and metadata parsing, while also updating the tar archive creation logic to support flattened directory structures for .apphosting outputs. Feedback focuses on improving the robustness of the build process by checking the binary's exit status, ensuring proper cleanup of stale artifacts and temporary directories, and removing hardcoded environment variables that might conflict with user configurations.

* Add a file cleanup callback * Clean up the file handling * Add error handling

…versal maker to share some code.

falahat · 2026-04-21T22:04:03Z

/gemini review

gemini-code-assist

Code Review

This pull request introduces the 'Universal Maker' binary for local builds in App Hosting, including logic for downloading, validating, and executing the tool. It also improves temporary file management during deployments by ensuring cleanup via callbacks. Several improvements were identified regarding the safety of command construction, the use of blocking synchronous calls in an asynchronous environment, and the need for better error handling and type safety in accordance with the repository's style guide.

gemini-code-assist · 2026-04-21T22:09:03Z

+    throw new FirebaseError(`Failed to parse build_output.json: ${(e as Error).message}`);
+  }
+
+  let finalRunCommand = `${umOutput.command} ${umOutput.args.join(" ")}`;


Constructing a command string by joining arguments with spaces can lead to broken commands if any argument contains spaces or special characters. It is safer to keep the command and arguments separate or use a utility that handles shell escaping.

gemini-code-assist · 2026-04-21T22:09:03Z

+    const res = childProcess.spawnSync(
+      universalMakerBinary,
+      ["-application_dir", projectRoot, "-output_dir", projectRoot, "-output_format", "json"],
+      {
+        env: {
+          ...process.env,
+          X_GOOGLE_TARGET_PLATFORM: "fah",
+          FIREBASE_OUTPUT_BUNDLE_DIR: bundleOutput,
+        },
+        stdio: "pipe",
+      },
+    );


Using spawnSync blocks the Node.js event loop until the process exits. For a build process that can take a significant amount of time, this can make the CLI feel unresponsive. Consider using an asynchronous spawn wrapped in a Promise to allow the event loop to remain active, which is also better for handling process signals like SIGINT.

gemini-code-assist · 2026-04-21T22:09:03Z

+    metadata: {
+      language: umOutput.language,
+      runtime: umOutput.runtime,
+      framework: framework || "nextjs",


The hardcoded default value "nextjs" should be extracted into a constant to improve maintainability and avoid magic strings.

gemini-code-assist · 2026-04-21T22:09:03Z

+export function validateSize(filepath: string, expectedSize: number): Promise<void> {
+  return new Promise((resolve, reject) => {
+    const stat = fs.statSync(filepath);
+    return stat.size === expectedSize
+      ? resolve()
+      : reject(
+          new FirebaseError(
+            `download failed, expected ${expectedSize} bytes but got ${stat.size}`,
+            { exit: 1 },
+          ),
+        );
+  });
+}


The validateSize function returns a Promise but performs synchronous file operations (fs.statSync). This is misleading and still blocks the event loop. It should either be fully synchronous or use fs.promises.stat to be truly asynchronous.

…hits.

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

…sal_maker

…ploy" flow as well

… the "deploy" flow as well" This reverts commit 59a79f5.

falahat added 2 commits April 16, 2026 17:18

create a prototype version of local builds that uses the universal maker

c573c6a

Add some gross hacks to stop bundle.yaml from being wiped empty

67cc1cc

gemini-code-assist Bot reviewed Apr 17, 2026

View reviewed changes

Comment thread src/apphosting/localbuilds.ts Outdated

Comment thread src/apphosting/localbuilds.ts

Comment thread src/apphosting/localbuilds.ts Outdated

Comment thread src/apphosting/secrets/index.ts

Comment thread src/deploy/apphosting/util.ts Outdated

Get rid of the watcher hack

a7cf61e

falahat changed the base branch from main to next April 17, 2026 18:11

gemini-code-assist Bot reviewed Apr 17, 2026

View reviewed changes

Comment thread src/apphosting/localbuilds.spec.ts Outdated

Comment thread src/apphosting/localbuilds.ts Outdated

Comment thread src/apphosting/localbuilds.ts Outdated

Comment thread src/deploy/apphosting/util.ts Outdated

falahat added 2 commits April 17, 2026 16:18

Address some review comments (unknown casts)

a2bce07

Address some other review comments

80f5aa1

gemini-code-assist Bot reviewed Apr 17, 2026

View reviewed changes

Comment thread src/apphosting/localbuilds.ts Outdated

Comment thread src/apphosting/localbuilds.ts Outdated

Comment thread src/apphosting/localbuilds.ts

Comment thread src/deploy/apphosting/util.ts

falahat added 6 commits April 17, 2026 16:29

Add a code comment

0bb1d5c

simplify local build code for tarballs

0bccdc2

simplify further

152505d

Further simplify diffs

d2185aa

Add automatic downloading of the UM binary

98e3c4f

Address review comments:

125676e

* Add a file cleanup callback * Clean up the file handling * Add error handling

joehan reviewed Apr 21, 2026

View reviewed changes

Comment thread src/apphosting/universalMakerDownload.ts Outdated

joehan reviewed Apr 21, 2026

View reviewed changes

Comment thread src/apphosting/universalMakerDownload.ts Outdated

falahat added 5 commits April 21, 2026 13:28

Create a common utility for downloading. This allows emulaotr and uni…

b8abe9b

…versal maker to share some code.

Fix FIREBASE_OUTPUT_BUNDLE_DIR

0cb9a89

formatting fix

ebd7d70

fix test

6469643

test fix

b846dbb

gemini-code-assist Bot reviewed Apr 21, 2026

View reviewed changes

falahat added 4 commits April 21, 2026 18:15

make the diffs smaller

9c3a64b

reduce diffs

2c40423

Make our hash validation more strict. ALWAYS validate, even on cache …

8a5ef6b

…hits.

format fix

c52080c

falahat and others added 8 commits April 21, 2026 18:28

format and test fix

064d9d1

fix tests

a8ebb98

Update src/apphosting/localbuilds.ts

2f13965

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Update src/apphosting/localbuilds.ts

9b2d82e

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

fix test

db9f107

Merge branch 'next' of github.com:firebase/firebase-tools into univer…

35ccb83

…sal_maker

Prompt for ABIU runtime settings when creating a backend from the "de…

59a79f5

…ploy" flow as well

Revert "Prompt for ABIU runtime settings when creating a backend from…

e6d1796

… the "deploy" flow as well" This reverts commit 59a79f5.

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falahat commented Apr 17, 2026 •

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