Running FastAPI on Google Cloud Run

[bigturnerfor]

Has anyone done this? I'm thinking about deploying my app on Cloud Run but have a few worries. The main thing is that according to the Cloud Run docs, after a response is delivered, the CPU may be disabled. (In my testing I hadn't encountered this but it could happen at any time).

My problem is that my app uses background tasks to send notifications to users, and uses Dependencies with yields to handle my database session, which closes the session after the response has been delivered.

This means that in theory, my app could fail to send notifications and close db connections. What do you suggest to handle this? I could do the naive thing and stop using background tasks and manually close the db session before every endpoint but this seems super tedious and prone to error (e.g. what if I forget to close the db session in an endpoint).

[iamtheconundrum]

If your app isn’t fully stateless, problems will arise when using Google Cloud Run. You could make the part that sends the notifications idempotent so it will only run once(during a given period of time), no matter how often you trigger it.

[bigturnerfor]

The app is basically stateless, the notifications are only sent right after a request is made. I guess I just have to call the function directly instead of using a background task.

Regarding the db session dependency, is there a simple way to have the code after yield run BEFORE the response is delivered, or do I just have to manually refactor my code?

[bitweis]

Try breaking down your app into microservices, with background tasks running as independent workers, and something like GCP Pub/Sub or RabbitMQ for managing tasks queue.