taskiq-beat 1.0.0

A database-backed scheduler and beat engine for Taskiq.

taskiq-beat

Scheduler for Taskiq with schedules and run history stored in the database

Navigation

• Quick start
• How to run it
• Run with FastAPI
• Create jobs
• Task chains
• Upsert and startup sync
• Manage jobs
• Logging
• Alembic
• Default configuration
• Create tables manually
• Load testing

Installation

pip install taskiq-beat

pip install "taskiq-beat[test]"
pip install "taskiq-beat[dev]"

taskiq-beat does not provide a network broker on its own. For real multi-process usage you usually also need a broker backend from the Taskiq ecosystem.

Quick start

from sqlalchemy.ext.asyncio import async_sessionmaker, create_async_engine
from taskiq import InMemoryBroker

from taskiq_beat import (
    ImmediateDispatch,
    IntervalTrigger,
    PeriodicSchedule,
    SchedulerApp,
    SchedulerConfig,
)

# SQLAlchemy engine used to connect to the database.
engine = create_async_engine("sqlite+aiosqlite:///scheduler.sqlite3")

# Factory that creates AsyncSession objects.
# Scheduler uses these sessions to work with the database.
session_factory = async_sessionmaker(engine, expire_on_commit=False)

# Taskiq broker for API demonstration.
# InMemoryBroker is not suitable for a separate worker process setup.
broker = InMemoryBroker()


@broker.task(task_name="demo.heartbeat")
async def heartbeat_task() -> None:
    print("tick")


# Main taskiq-beat entry point.
scheduler_app = SchedulerApp(
    broker=broker,
    session_factory=session_factory,
    config=SchedulerConfig(
        # How often the scheduler reloads active jobs from the database.
        sync_interval_seconds=1.0,
        # Minimum pause between scheduler loop iterations.
        idle_sleep_seconds=0.2,
        # How many seconds to wait before retrying dispatch after task.kiq(...) fails.
        dispatch_retry_seconds=5,
        # How many jobs can be dispatched concurrently inside one batch.
        dispatch_concurrency=32,
        # Maximum number of due jobs taken from the heap in one batch.
        dispatch_batch_size=256,
        # Whether to write history rows into SchedulerRun.
        record_runs=True,
        # Base timezone for helper APIs if another timezone is not specified explicitly.
        default_timezone="UTC",
    ),
)

This example only shows how to assemble broker, session_factory, and scheduler_app. It does not mean tasks will already start executing in a separate process.

How to run it

The example above only creates Python objects. That is still not enough for the system to start working by itself.

What a real application needs:

1. Start a process with scheduler_app.start().
2. Start a Taskiq worker process that will consume tasks from the broker.
3. Create jobs through scheduler_app.single(task=...).schedule(session) or scheduler_app.chain(steps=[...]).schedule(session).

Important:

• InMemoryBroker in the examples is only suitable for API demos, tests, and local experiments inside one process.
• If you want a separate worker in another terminal or service, you need a real broker backend.
• A worker is usually started in a separate terminal or a separate service/process.
• The command python -m taskiq worker app.main:broker means: import the broker object from the app.main module and listen to its queue.

Typical scenario:

• terminal 1: FastAPI with scheduler_app.start() inside lifespan
• terminal 2: Taskiq worker
• terminal 3: API requests or a separate script that creates jobs

The most common FastAPI setup looks like this:

1. app/main.py contains broker, scheduler_app, app = FastAPI(...), and task functions.
2. In the first terminal, start FastAPI:

uvicorn app.main:app --reload

3. In the second terminal, start the worker:

python -m taskiq worker app.main:broker

4. After that, create jobs through an API, script, or Python shell.

What happens after startup:

• the scheduler watches the schedule and calls task.kiq(...) at the required moment
• the broker publishes the task
• the worker takes the task and executes it

If the worker is not running, the scheduler can publish tasks into the broker, but nothing will execute them.

If you want to run the scheduler separately instead of inside FastAPI, that is also possible. Then one process keeps scheduler_app.start(), and another process still remains the Taskiq worker.

Run with FastAPI

from contextlib import asynccontextmanager
from fastapi import FastAPI
from sqlalchemy.ext.asyncio import async_sessionmaker, create_async_engine
from taskiq import InMemoryBroker

from taskiq_beat import SchedulerApp, SchedulerConfig

engine = create_async_engine("sqlite+aiosqlite:///scheduler.sqlite3")
session_factory = async_sessionmaker(engine, expire_on_commit=False)
broker = InMemoryBroker()
scheduler_app = SchedulerApp(
    broker=broker,
    session_factory=session_factory,
    config=SchedulerConfig(),  # Configuration was shown above
)


@asynccontextmanager
async def lifespan(app: FastAPI):
    await broker.startup()
    await scheduler_app.start()
    try:
        yield
    finally:
        await scheduler_app.stop()
        await broker.shutdown()


app = FastAPI(lifespan=lifespan)

Scheduler can run:

• Inside FastAPI

  As in the example above

• Separately

  • terminal/container 1: uvicorn app.main:app --reload
  • terminal/container 2: python -m app.run_scheduler
  • terminal/container 3: python -m taskiq worker app.broker:broker

Both approaches are valid. The main rule is: do not run several scheduler processes against the same database.

Create jobs

The public API has two builders on SchedulerApp:

• scheduler_app.single(task=...) — schedule a single task.
• scheduler_app.chain(steps=[...]) — schedule an ordered chain of tasks.

Both builders expose .schedule(session, trigger=...) and .upsert(session, trigger=..., job_id=...). If trigger is omitted in .schedule(...), taskiq-beat uses ImmediateDispatch(): the task is sent to the broker right away and the job/run records are stored in the database.

from datetime import UTC, datetime, timedelta

from taskiq_beat import ImmediateDispatch, IntervalTrigger, OneOffSchedule, PeriodicSchedule

# Default: immediate task.kiq(...) + database record.
await scheduler_app.single(task=heartbeat_task).schedule(session)

# Equivalent explicit form.
await scheduler_app.single(task=heartbeat_task).schedule(
    session,
    trigger=ImmediateDispatch(),
)

# Explicit delayed or periodic scheduling.
await scheduler_app.single(task=heartbeat_task).schedule(
    session,
    trigger=OneOffSchedule(run_at=datetime.now(UTC) + timedelta(minutes=10)),
)
await scheduler_app.single(task=heartbeat_task).schedule(
    session,
    trigger=PeriodicSchedule(interval=IntervalTrigger(minutes=5)),
)

ImmediateDispatch is only valid with .schedule(...). Use a real schedule trigger with .upsert(...).

Interval job

from taskiq_beat import IntervalTrigger, PeriodicSchedule

async with session_factory() as session:
    job = await scheduler_app.single(task=heartbeat_task).schedule(
        session,
        trigger=PeriodicSchedule(interval=IntervalTrigger(seconds=5)),
        name="Heartbeat every 5 seconds",
    )

print(job.id)  # Example: "6c6342d8-6d74-4d16-8f7a-5d4f1b3a0b13"

.schedule(session, ...) returns SchedulerJob. This is a SQLAlchemy model instance with fields such as:

• job.id
• job.task_name
• job.kind
• job.strategy
• job.next_run_at
• job.is_enabled

Most of the time you use job.id later for pause, resume, run-now, and delete.

If you want a stable identifier for a system job, use .upsert(...) with an explicit job_id:

async with session_factory() as session:
    job = await scheduler_app.single(task=heartbeat_task).upsert(
        session,
        trigger=PeriodicSchedule(interval=IntervalTrigger(minutes=5)),
        job_id="system.heartbeat",
        name="System heartbeat",
    )

One-off job

from datetime import UTC, datetime, timedelta

from taskiq_beat import OneOffSchedule

async with session_factory() as session:
    job = await scheduler_app.single(task=heartbeat_task).schedule(
        session,
        trigger=OneOffSchedule(run_at=datetime.now(UTC) + timedelta(minutes=10)),
        name="Delayed heartbeat",
    )

Crontab job

from taskiq_beat import CrontabTrigger, PeriodicSchedule

async with session_factory() as session:
    job = await scheduler_app.single(task=heartbeat_task).schedule(
        session,
        trigger=PeriodicSchedule(
            crontab=CrontabTrigger(second="0", minute="*/5", hour="*"),
        ),
        name="Every 5 minutes",
    )

Passing args and kwargs to the task

async with session_factory() as session:
    await scheduler_app.single(
        task=heartbeat_task,
        args=[42],
        kwargs={"label": "ping"},
        metadata={"scope": "system"},
    ).schedule(
        session,
        trigger=PeriodicSchedule(interval=IntervalTrigger(minutes=1)),
    )

Task chains

Taskiq does not enforce ordered execution of multiple tasks out of the box. taskiq-beat adds a small built-in orchestrator that runs tasks one after another and persists the chain as a regular scheduler job.

The orchestrator task is registered automatically inside every SchedulerApp under the name taskiq_beat.chain_orchestrator. When the schedule fires, the scheduler enqueues this orchestrator; the orchestrator then dispatches every step to the broker via task.kiq(...) and awaits the result before moving on to the next one.

from datetime import UTC, datetime

from taskiq_beat import ChainStep, IntervalTrigger, OneOffSchedule, PeriodicSchedule

@broker.task(task_name="reports.collect")
async def collect_report(year: int, month: int) -> dict:
    ...


@broker.task(task_name="reports.render")
async def render_report(*, format: str) -> bytes:
    ...


@broker.task(task_name="reports.upload")
async def upload_report() -> str:
    ...


async with session_factory() as session:
    # Run once, immediately.
    await scheduler_app.chain(
        steps=[
            ChainStep(task=collect_report, args=[2026, 4]),
            ChainStep(task=render_report, kwargs={"format": "pdf"}, max_attempts=3, post_delay_ms=500),
            ChainStep(task=upload_report, timeout_seconds=120.0),
        ],
        on_failure="stop",             # "stop" or "restart"
        max_chain_attempts=2,          # how many times the whole chain may run
        default_step_max_attempts=1,   # default per-step retry budget
        default_step_retry_delay_seconds=0.0,
        default_step_timeout_seconds=None,  # None = wait forever for result
        wait_poll_interval_seconds=0.5,
    ).upsert(
        session,
        trigger=OneOffSchedule(run_at=datetime.now(UTC)),
        job_id="reports.monthly.one_off",
        name="Monthly report chain",
    )

    # Or schedule it periodically like any other job.
    await scheduler_app.chain(
        steps=[
            ChainStep(task=collect_report, args=[2026, 4]),
            ChainStep(task=render_report, kwargs={"format": "pdf"}, max_attempts=3, post_delay_ms=500),
            ChainStep(task=upload_report, timeout_seconds=120.0),
        ],
    ).upsert(
        session,
        trigger=PeriodicSchedule(interval=IntervalTrigger(hours=6)),
        job_id="reports.monthly",
        name="Monthly report chain",
    )

Options

• ChainStep.task — accepts the Taskiq task object itself (result of @broker.task(...)) or its string name if importing the task is inconvenient.
• ChainStep.args / ChainStep.kwargs — must be JSON-serializable, same as for a regular schedule.
• ChainStep.max_attempts — per-step retry budget. Overrides default_step_max_attempts.
• ChainStep.retry_delay_seconds — delay between attempts of a single step.
• ChainStep.timeout_seconds — maximum time to wait for a single step result; None waits forever.
• ChainStep.post_delay_ms — delay in milliseconds after a successful step before the next step starts.
• chain(..., on_failure=...) — "stop" aborts the chain and raises on the worker, "restart" starts the chain over from the first step.
• chain(..., max_chain_attempts=...) — upper bound on chain restarts; 1 disables restart.

Failure handling

Per-step retries run inside the orchestrator, so intermittent errors are absorbed transparently. If a step exhausts its attempts:

• with on_failure="stop" the orchestrator raises ChainAbortedError, which the worker logs as a failed task.
• with on_failure="restart" the chain re-runs from the first step until max_chain_attempts is reached, then raises ChainAbortedError.

Scheduler-level retries (dispatch_retry_seconds) still apply to the orchestrator itself when task.kiq(...) cannot be delivered to the broker.

Requirements

task.wait_result(...) is used to wait for each step, so the broker must have a result backend configured. InMemoryBroker has one built in; for production brokers attach a result backend such as Redis or database-based implementations from the Taskiq ecosystem.

Because the orchestrator runs as a regular worker task, it occupies a worker slot for the full duration of the chain. Size your worker pool accordingly.

Upsert and startup sync

For system schedules you usually do not want duplicate rows after every restart.

Use a stable job_id and call .upsert(...):

async with session_factory() as session:
    await scheduler_app.single(task=heartbeat_task).upsert(
        session,
        trigger=PeriodicSchedule(interval=IntervalTrigger(hours=1)),
        job_id="system.cleanup",
        name="Cleanup",
    )

.upsert(...) behavior:

• creates a new row if the job does not exist yet
• updates the existing row if job_id already exists
• does not create duplicates on restart
• preserves next_run_at if the schedule did not change
• recalculates next_run_at if trigger or enabled state changed

For several schedules at startup, just upsert them in a row:

async with session_factory() as session:
    await scheduler_app.single(task=heartbeat_task).upsert(
        session,
        trigger=PeriodicSchedule(interval=IntervalTrigger(hours=1)),
        job_id="system.cleanup",
        name="Cleanup",
    )
    await scheduler_app.single(task=heartbeat_task).upsert(
        session,
        trigger=PeriodicSchedule(interval=IntervalTrigger(minutes=5)),
        job_id="system.metrics",
        name="Metrics",
    )
    await scheduler_app.chain(steps=[...]).upsert(
        session,
        trigger=PeriodicSchedule(interval=IntervalTrigger(hours=6)),
        job_id="system.reports",
        name="Reports chain",
    )

This is the recommended way to register built-in application schedules during startup.

Manage jobs

What you need:

• session_factory() to open an AsyncSession
• job.id, which is usually taken from the result of await scheduler_app.single(task=...).schedule(session, trigger=...)

async with session_factory() as session:
    await scheduler_app.pause(session, job.id)
    await scheduler_app.resume(session, job.id)
    await scheduler_app.run_now(session, job.id)
    await scheduler_app.delete(session, job.id)

Logging

taskiq-beat uses the standard Python logging module. The library emits logs, but does not configure handlers, files, or external storage by itself.

This is intentional:

• the application decides where logs go
• local development usually sends them to stdout
• Docker setups usually read them through container logs
• production systems usually forward them to Loki, ELK, Datadog, Cloud Logging, and similar tools

Basic setup:

import logging

logging.basicConfig(
    level=logging.INFO,
    format="%(asctime)s %(levelname)s %(name)s %(message)s",
)

This will show logs from taskiq_beat.app, taskiq_beat.scheduler, and taskiq_beat.engine.

Typical events that are logged:

• scheduler app start and stop
• scheduler engine sync from storage
• scheduler job create, upsert, pause, resume, run-now, delete
• successful dispatches
• dispatch failures with retry scheduling

If your worker and API run in containers, it is usually enough to log to stdout and collect logs from Docker or Kubernetes.

Alembic

To make Alembic detect scheduler tables, add SchedulerBase.metadata to target_metadata.

alembic/env.py:

from myapp.db import Base
from taskiq_beat import SchedulerBase

target_metadata = [
    # Your main ORM metadata.
    Base.metadata,
    # Metadata from taskiq-beat.
    SchedulerBase.metadata,
]

Commands you can copy directly:

pip install alembic
alembic init alembic
alembic revision --autogenerate -m "add taskiq beat tables"
alembic upgrade head

Alembic should detect:

• scheduler_job
• scheduler_run

Create tables manually

Use this only for local runs, tests, and quick experiments.

from taskiq_beat import SchedulerBase

async with engine.begin() as connection:
    await connection.run_sync(SchedulerBase.metadata.create_all)

These tables will be created:

• scheduler_job
• scheduler_run

Load testing

See scripts/README.md.

Testing

pytest