Hi community, is there a way to change the flow run context during a task run, so that the subsequent tasks can see the updated context values?

@Dan Zhao can you describe the use case for which you would want to use it? In general, mutating the context from within a task is not recommended as it will not behave consistently across execution environments. But you can do that using the context manager:

import prefect

with prefect.context(dict(a=1, b=2)):
    print(prefect.context.a) # 1

print(prefect.context.get("a")) # undefined

More on that: • https://docs.prefect.io/api/latest/utilities/context.html • https://docs.prefect.io/core/concepts/execution.html#prefect-supplied-context If you are on Cloud, you can use the KV Store instead of context to store a small piece of information that you can access across tasks: https://docs.prefect.io/orchestration/concepts/kv_store.html#kv-store

I am hoping to alter some system status (basically environment variables, but context sounds like a more robust option) from within a task's run method. Subsequent tasks should be able to see these changes.

if those variables are sensitive, you could leverage PrefectSecret, otherwise you can also set environment variables within your run configuration - those will be then applied on a flow-level.

flow.run_config = UniversalRun(env={"SOME_VAR": "value"})

for the run configuration approach - is it possible to change it during a task run, while allowing subsequent tasks to see it?

For that I would rather use KV Store. I mean, you can of course do this in your task:

import os
os.environ["YOUR_ENV_VARIABLE"] = "VALUE"

but it’s not as reliable as setting it with KV Store:

from prefect.backend import set_key_value

key_value_uuid = set_key_value(key="YOUR_ENV_VARIABLE", value="VALUE")