Lightweight scheduler for python asyncio
Based on croniter to support the crontab syntax.
Installing acron.
$ pip install acron
To get started you need at least one job.
Use the top level acron.run
function for simple scheduling.
Use SimpleJob
to run a simple async function with no associated data.
import asyncio
import acron
async def do_the_thing():
print("Doing the thing")
do_thing = acron.SimpleJob(
name="Do the thing",
schedule="0/1 * * * *",
func=do_the_thing,
)
asyncio.run(acron.run({do_thing}))
For more advanced use cases, the Scheduler
class can be used as async context manager.
Call scheduler.wait()
to keep it running forever.
To submit jobs call scheduler.update_jobs(jobs)
with the complete set of jobs.
Running an example Job
running a function with associated data every hour...
import asyncio
import dataclasses
from acron.scheduler import Scheduler, Job
@dataclasses.dataclass(frozen=True)
class ThingData:
foo: bool
async def do_the_thing(data: ThingData):
print(f"Doing the thing {data}")
async def run_jobs_forever():
do_thing = Job[ThingData](
name="Do the thing",
schedule="0/1 * * * *",
data=ThingData(True),
func=do_the_thing,
)
async with Scheduler() as scheduler:
await scheduler.update_jobs({do_thing})
await scheduler.wait()
if __name__ == "__main__":
try:
asyncio.run(run_jobs_forever())
except KeyboardInterrupt:
print("Bye.")
For python 3.9+ you can use the standard library's zoneinfo
module to specify a timezone.
import zoneinfo
async with Scheduler(tz=zoneinfo.ZoneInfo("Europe/Berlin")) as scheduler:
...
For earlier python versions you can use a third party library like pytz
.
import pytz
async with Scheduler(tz=pytz.timezone("Europe/Berlin")) as scheduler:
...
It is possible to retrieve the context for the scheduled job from the running
job function using job_context()
. This returns a JobContext
containing
a reference to the ScheduledJob
. The job_context()
function is implemented
using contextvars to provide the correct context to the matching asyncio task.
async def my_job_func():
job_id = acron.job_context().scheduled_job.id
job_name = acron.job_context().scheduled_job.job.name
print(f"Running job {job_id!r}, scheduled with id {job_id}")
The project uses poetry to run the test, the linter and to build the artifacts.
The easiest way to start working on acron is to use docker with the dockerfile included in the repository (manual usage of poetry is explained here: https://python-poetry.org/docs/ ).
To use docker, first generate the docker image. Run this command from the top level directory in the repository:
docker build -t acron-builder -f docker/Dockerfile .
Now you can use it to build or run the linter/tests:
$ alias acron-builder="docker run --rm -it -v $PWD/dist:/build/dist acron-builder"
$ acron-builder run pytest tests
=============================================================================================== test session starts ================================================================================================
platform linux -- Python 3.9.7, pytest-5.4.3, py-1.10.0, pluggy-0.13.1
rootdir: /build
plugins: asyncio-0.15.1
collected 4 items
tests/test_acron.py .... [100%]
================================================================================================ 4 passed in 0.04s =================================================================================================
$ acron-builder build
Building acron (0.1.0)
- Building sdist
- Built acron-0.1.0.tar.gz
- Building wheel
- Built acron-0.1.0-py3-none-any.whl
$ ls dist
acron-0.1.0-py3-none-any.whl acron-0.1.0.tar.gz
Debug logging can be enabled by setting the ACRON_DEBUG
environment variable to TRUE
.