Import and use BackgroundTasks with parameters in path operation functions and dependencies to add background tasks.

To see an example, check the Project Generators, they all include Celery already configured.īut if you need to access variables and objects from the same FastAPI app, or you need to perform small background tasks (like sending an email notification), you can simply just use BackgroundTasks. They tend to require more complex configurations, a message/job queue manager, like RabbitMQ or Redis, but they allow you to run background tasks in multiple processes, and especially, in multiple servers. If you need to perform heavy background computation and you don't necessarily need it to be run by the same process (for example, you don't need to share memory, variables, etc), you might benefit from using other bigger tools like Celery. You can see more details in Starlette's official docs for Background Tasks. It's still possible to use BackgroundTask alone in FastAPI, but you have to create the object in your code and return a Starlette Response including it. It is imported/included directly into FastAPI so that you can import it from fastapi and avoid accidentally importing the alternative BackgroundTask (without the s at the end) from starlette.background.īy only using BackgroundTasks (and not BackgroundTask), it's then possible to use it as a path operation function parameter and have FastAPI handle the rest for you, just like when using the Request object directly. So try running it in a thread, just like you did in the main one: subprocess. The class BackgroundTasks comes directly from starlette.background. It seems you have a problem with either 1) the fact that it is run in a thread (we have a problem) 2) the parameters you passed to subprocess.Popen. If there was a query in the request, it will be written to the log in a background task.Īnd then another background task generated at the path operation function will write a message using the email path parameter.

In this example, the messages will be written to the log.txt file after the response is sent. From fastapi import BackgroundTasks, FastAPI app = FastAPI () def write_notification ( email : str, message = '' ): with open ( 'log.txt', mode = 'w' ) as email_file : content = f 'notification for

Python subprocess run in background