beatit 2022.3.1

A simple backend agnostic heartbeating convention

beatit

A simple backend agnostic heartbeating convention.

>>> class Printer:
...     @staticmethod
...     def publish(*, subject: bytes, payload: bytes):
...         print(f"{payload} -> {subject}")
>>> from beatit import Heart
>>> heart = Heart(process="my.process.identifier", publisher=Printer)
>>> heart.start(warmup=60)
b'start/60' -> b'heartbeat.my.process.identifier'
>>> heart.beat(period=5)
b'beat/5' -> b'heartbeat.my.process.identifier'
>>> heart.beat(period=5)
>>> heart.degraded(period=5)
b'degraded/5' -> b'heartbeat.my.process.identifier'
>>> heart.degraded(period=5)
>>> heart.stop()
b'stop' -> b'heartbeat.my.process.identifier'

All you need is a publisher with a publish method accepting two named arguments subject and payload.

Instantiate a Heart instance with a process name and a publisher. beats will be published on the subject heartbeat.<process>.

What are the beats?

start with a warmup period (after which a beat or a degraded is expected)

beat with a period (when to expect the next beat).

degraded with a period (when to expect a beat or a degraded next).

stop when the process stops gracefully.

sync or not ...

If you favour async (what is wrong with you?) Heart recognizes an async publisher automagically and all you have to do is await all the things.

>>> import asyncio
>>> class AsyncPrinter:
...     @staticmethod
...     async def publish(*, subject: bytes, payload: bytes):
...         print(f"{payload} -> {subject}")
>>> from beatit import Heart
>>> heart = Heart(process="my.process.identifier", publisher=AsyncPrinter)
>>> asyncio.run(heart.start(warmup=60))
b'start/60' -> b'heartbeat.my.process.identifier'
>>> asyncio.run(heart.beat(period=5))
b'beat/5' -> b'heartbeat.my.process.identifier'
>>> asyncio.run(heart.beat(period=5))
>>> asyncio.run(heart.degraded(period=5))
b'degraded/5' -> b'heartbeat.my.process.identifier'
>>> asyncio.run(heart.degraded(period=5))
>>> asyncio.run(heart.stop())
b'stop' -> b'heartbeat.my.process.identifier'

subject_as_string

beatit calls publish with bytes subject and payload. Seemed consistent but common publishers favour str for subject.

Fear not, here is a @limx0 approved solution!

>>> class StrBytes:
...     @staticmethod
...     def publish(*, subject: str, payload: bytes):
...         print(f"{payload} -> {subject}")
>>> from beatit import Heart
>>> heart = Heart(process="my.process.identifier", publisher=StrBytes, subject_as_string=True)
>>> heart.start(warmup=30)
b'start/30' -> heartbeat.my.process.identifier