Celery chain breaks if one of the tasks fail

Question

What is the point of Celery chain if the whole chain breaks if one of the tasks fail?!!

I have this Celery chain:

res = chain(workme.s ( y=1111 ), workme2.s( 2222 ), workme3.s( 3333 ),)() 

And I made workme2 fails with retries like this:

@celery.task(default_retry_delay=5, max_retries = 10, queue="sure") 
def workme2(x,y):
    # try:      
    try:
        print str(y)
        sleep(2)
        print str(x)
        ## adding any condition that makes the task fail
        if x!=None:
            raise Exception('Aproblem from your workme task')
        print 'This is my username: ' + str(x['user']) + \
               ' And Password: ' + str(x['pas'])        
        return "22xx"
    except Exception, exc:
        workme2.retry(args=[x,y], exc=exc,)

Answer 1

That is the point.

Forming a chain means your subtasks have some kind of serial dependency: Each one only makes sense if the previous one has been performed. Without this, you would simply use queueing or use a group rather than a chain.

So if one subtask fails (and still fails after attempting all its retries), the chain fails.

I readily admit that the documentation (as of Celery 3.1.18) is far from explicit in this respect, but the name suggests this semantics: "A chain is only as strong as its weakest link."