taskferry-procrastinate

Run Taskferry tasks on Procrastinate — a durable, PostgreSQL-backed task engine.

flowchart LR
    APP["Application"]
    TP["Taskferry"]
    AD["taskferry-procrastinate"]
    PRO["Procrastinate"]
    PG["PostgreSQL"]

    APP --> TP --> AD --> PRO --> PG

Taskferry does not implement a queue, a worker, job reservation or retries. Procrastinate already does all of that, correctly, on PostgreSQL. This package is the translation layer between the two — and nothing else.

Install

pip install 'taskferry-procrastinate[procrastinate]'

PostgreSQL becomes a dependency of your deployment only once you select this backend. taskferry itself has no dependencies at all.

Submitting

from taskferry import Taskferry

runtime = Taskferry.from_mapping(
    {
        "backends": {"pg": {"factory": "procrastinate", "app": "myapp.tasks:app"}},
        "defaults": {"task": "pg"},
    }
)

runtime.tasks.submit("myapp.tasks:refresh_metadata", 42, queue="metadata")

Executing

Register the dispatcher once, then run Procrastinate's own worker:

# myapp/tasks.py
from procrastinate import App, PsycopgConnector
from taskferry import FunctionRegistry
from taskferry_procrastinate import register_dispatcher

app = App(connector=PsycopgConnector(conninfo="postgresql://..."))

# An allowlist matters: task names arrive from the queue.
register_dispatcher(app, registry=FunctionRegistry(allowed_modules=["myapp"]))

procrastinate --app=myapp.tasks.app worker

Capabilities

RESULT is absent because Procrastinate genuinely does not keep results. Taskferry raises UnsupportedCapability rather than inventing a results table — building queue features is precisely what this project exists not to do.

Backend options

TaskSpec(
    task="myapp.tasks:reindex",
    backend_options=BackendOptions(
        {
            "procrastinate": {
                "lock": "reindex-42",  # serialise jobs against a key
                "queueing_lock": "reindex",  # refuse a duplicate while one is pending
            }
        }
    ),
)

License

Apache-2.0.