Minimal Reproducible Test for Firebase Cloud Functions Emulator Issues

This is a minimal setup to reproduce specific behavior and issues with Cloud Functions and Pub/Sub topics on the Firebase emulator.

Setup and Commands

Prerequisites

• Docker and Docker Compose
• Make

Running the Tests

1. Start the environment:

   make compose

   This will automatically detect your platform (Mac/Linux) and start all required services.

2. Run the tests:

   make test

Expected Behavior and Issues

First Run

• First test will fail: Pub/Sub seems to lose the first message for some reason when the emulator is just started
• Second test will succeed: The test that updates 100 products should work properly

Second Run (Immediately)

• Tests fail randomly: The emulator appears to kill functions after 30 seconds regardless of configuration, breaking tests

Second Run (After Functions Cool Down)

If you check the console and see that functions have ended like this:

firebase-1   | i  functions: Finished "europe-west4-products_sync_bulk" in 29054.191729ms
firebase-1   | i  functions: Finished "europe-west4-products_sync_bulk" in 29056.899779ms
firebase-1   | i  functions: Finished "europe-west4-products_sync_bulk" in 29055.842414ms
firebase-1   | i  functions: Finished "europe-west4-products_sync_bulk" in 29057.540609ms
firebase-1   | i  functions: Finished "europe-west4-products_sync_bulk" in 29058.24203ms
firebase-1   | i  functions: Finished "europe-west4-products_sync_bulk" in 29056.543984ms
firebase-1   | i  functions: Finished "europe-west4-products_sync_bulk" in 29051.259175ms
firebase-1   | i  functions: Finished "europe-west4-products_sync_bulk" in 29010.059986ms

Then running the tests again should result in both tests passing.

Issues for Google Team Investigation

1. Random Connection Errors

In our full test suite, we sometimes see unexplained random errors such as:

• firebase Connection in use: ('127.0.0.1', 8996)
• Error: socket hang up
• ERRCONNRESET
• function failed to load

2. Function Instance Management

The @pubsub_fn decorator creates many instances on the emulator, despite being configured with:

min_instances=1,
max_instances=1,
concurrency=1,

Question: Please verify this behavior against the expected implementation. Should the emulator respect these instance limits?

3. Function Timeout Behavior

Functions appear to be terminated after approximately 30 seconds regardless of the configured timeout, causing test failures when run consecutively.

Structure

• functions/python/ - Cloud Functions code
• functions/python/app/tests/ - Test suite
• docker-compose.yaml - Service configuration
• Makefile - Build and test commands