Is it possible to statically type the code used to deploy Prefect flows without converting it all to async? We have a script we are running to deploy flows

from prefect.deployments import Deployment
from prefect.filesystems import S3
s3_block = S3(
    aws_access_key_id=aws_key,
    aws_secret_access_key=aws_secret,
    bucket_path=context["prefect_flows_bucket"],
)
s3_block.save("s3", overwrite=True)

Deployment.build_from_flow(
    name="alpha",
    work_queue_name="alpha",
    flow=healthcheck,
    storage=S3.load("s3"),
    infrastructure=Process(),
    apply=True,
)

When we run mypy on this code, it complains about things not being typed as async. Is it possible to type this code without converting to async?

not directly but why don't you leverage the CLI instead? it would make things easier and you could put this directly into CI/CD

@Anna Geller I’ve been using

dataflow-ops

a lot - it’s great ❤️

why don’t you leverage the CLI instead

We started out using the CLI but have ended up doing everything in Python. We will reconsider this decision in light of the async requirement for static typing of Prefect deployments.

As Anna mentioned, the CLI route is probably easiest. But if typed Python is advantageous for your use case, you might try assigning the results of both method calls and then using them by doing something like:

result = s3_block.save("s3", overwrite=True)
assert result is not None

and then something similar for

Deployment.build_from_flow

. I'd expect both methods to throw an exception if something happened that would cause them to return

None

. But doing it this way (if you don't find it to be a hassle) should make MyPy happy and also give you an extra bit of validation if you run your deployments with assertions enabled. You could also skip the assert, but then your tooling might be unhappy about the unused

result

variable. To add a bit of detail on what is happening: it is fine to run both those methods non asynchronously because they use the sync_compatible decorator, but MyPy doesn't know it's okay to run them that way and so it complains if you just call them without either awaiting them or assigning their result to something.