dagler 0.0.2

DAG pipeline orchestration built on qler + sqler

dagler

Pipeline orchestration without Airflow, built on qler + SQLite.

dagler is a DAG pipeline orchestration library for Python. Each task runs as a qler job, SQLite is the only infrastructure, and pipelines are defined with Python decorators.

The -ler Stack

Layer	Tool	Responsibility
Storage	sqler	SQLite ORM, async, optimistic locking
Queues	qler	Background job execution
Pipelines	dagler	DAG orchestration (this project)

Install

uv add dagler

Quick Start

from dagler import DAG

dag = DAG("etl_pipeline")

@dag.task
async def extract():
    return await fetch_data()

@dag.task(depends_on=[extract])
async def transform(data):
    return process(data)

@dag.task(depends_on=[transform])
async def load(data):
    await write_to_db(data)

# Submit a pipeline run
run = await dag.run(queue)
await run.wait()

Features

• Declarative DAGs — Python decorators, not YAML
• Automatic result passing — parent results injected into child tasks
• Dynamic fan-out — @dag.map_task splits work, @dag.reduce_task collects results
• Pipeline tracking — every dag.run() creates a tracked DagRun with status rollup
• LLM-agent friendly CLI — structured JSON output, actionable errors, discoverable schemas
• SQLite-only — no Redis, no Postgres, no external brokers

CLI

dagler init          # Initialize the database
dagler run <dag>     # Submit a pipeline run
dagler runs          # List pipeline runs
dagler run-info <id> # Inspect a specific run
dagler cancel <id>   # Cancel a running pipeline
dagler retry <id>    # Retry a failed pipeline
dagler wait <id>     # Block until a run completes

Contributing

See CLAUDE.md for project architecture and contributor docs.

License

MIT