Demonstrate over-aggressive synchronous subtask check in eager application

minimal_eager_chain.py

"""Celery master is too aggressive about suppressing .get() in eager tasks.

test performs no synchronous operations, but fails in eager application::

  python minimal_eager_chain.py shell --config=minimal_eager_chain
  test.delay().get()
"""

import celery
from celery.canvas import chord

app = celery.Celery()

CELERY_RESULT_BACKEND = "redis://localhost/0"
CELERY_ALWAYS_EAGER = True


@app.task()
def a():
    return 42


@app.task()
def b(ar):
    return ar


@app.task()
def test():
    (
        a.s() | b.s()
    ).apply_async()


def main():
    app.start()


if __name__ == '__main__':
    main()