sqlalchemy is not supported as kombu transport

[Boris Bobrov]

sqlalchemy cannot be used as a kombu transport any more. It was removed: ​https://github.com/celery/celery/issues/3274#issuecomment-228324848, kombu commit 1cd4e07f9ebb2fdbde0f86054e963f6bbd17e698.
For now i have capped kombu and celery to <4.0, but we need to figure out what to do.

[ayleph]

Based on feedback from IRC, it seems that capping at "<4.0" doesn't prevent 4.0.0rc3 from being downloaded. Stack Overflow suggests using a syntax like "<4.0a0".

​https://stackoverflow.com/a/14405269

Edited to indicate that I hadn't experienced this myself, but that I heard about in in IRC.

[ayleph]

I downloaded latest stable branch from git and the "<4.0" stuff seemed to work fine when following the build instructions for py2 and py3. I don't know why it didn't work for the user in IRC.

[jerome]

I had the same issue but ​474a56 didn't fixed that. I had to specify "<4.0a0" as suggested by ayleph, otherwise celery==4.0.0rc3 and kombu==4.0.0rc3 was installed.

[ayleph]

Replying to jerome:

I had to specify "<4.0a0" as suggested by ayleph, otherwise celery==4.0.0rc3 and kombu==4.0.0rc3 was installed.

Thanks for confirming that worked for you. I've pushed that change to master in ​d37c6f6 and cherry-picked onto stable.

[Christopher Allan Webber]

Per our discussions in today's meeting, we'll move to a more official broker for those who are running celery separately. Considering that it's widely packaged, and that Redis is a little bit less certain (​it was the original topic of removal in that bug, but has since been preserved), we will probably go with RabbitMQ. This will mean changing our docs and etc.

[Ben Sturmfels]

Marking as "large" assuming that this will require a significant infrastructure change to fully resolve.