Throttle Pub/Sub Cloud Function

Google Cloud function that can throttle messages in a Pub/Sub topic. It uses a GCS bucket with a Retention Policy to store a lock file. Last modified date of this file is used to decide whether a message should be throttled. Retention Policy prevents race conditions in case of high contention. The GCS bucket should be used to store a lock only if the performance is not critical. In other cases Redis can be used instead.

1. Create a GCS bucket with a Retention Policy with Duration 60 seconds.

2. Update config.sh with your values:

• LOCK_BUCKET - the name of your bucket.
• LOCK_EXPIRATION_IN_SECONDS - 1 message per LOCK_EXPIRATION_IN_SECONDS seconds will passed, other messages will be throttled. Must be more than 60.
• others are self-explanatory.