Hi Jarek, I will +1 the discussion Dan is referring to and George's advice.
I just want to double check we are talking about pinning in requirements.txt only. This offers the ability to pip install -r requirements.txt pip install --no-deps airflow For a guaranteed install which works. Several different requirement files can be provided for specific use cases, like a stable dev one for instance for people wanting to work on operators and non-core functions. However, I think we should proactively test in CI against unpinned dependencies (though it might be a separate case in the matrix) , so that we get advance warning if possible that things will break. CI downtime is not a bad thing here, it actually caught a problem :) We should unpin as possible in setup.py to only maintain minimum required compatibility. The process of pinning in setup.py is extremely detrimental when you have a large number of python libraries installed with different pinned versions. Best, Arthur On Thu, Oct 4, 2018 at 8:36 AM Dan Davydov <ddavy...@twitter.com.invalid> wrote: > Relevant discussion about this: > > https://github.com/apache/incubator-airflow/pull/1809#issuecomment-257502174 > > On Thu, Oct 4, 2018 at 11:25 AM Jarek Potiuk <jarek.pot...@polidea.com> > wrote: > > > TL;DR; A change is coming in the way how dependencies/requirements are > > specified for Apache Airflow - they will be fixed rather than flexible > (== > > rather than >=). > > > > This is follow up after Slack discussion we had with Ash and Kaxil - > > summarising what we propose we'll do. > > > > *Problem:* > > During last few weeks we experienced quite a few downtimes of TravisCI > > builds (for all PRs/branches including master) as some of the transitive > > dependencies were automatically upgraded. This because in a number of > > dependencies we have >= rather than == dependencies. > > > > Whenever there is a new release of such dependency, it might cause chain > > reaction with upgrade of transitive dependencies which might get into > > conflict. > > > > An example was Flask-AppBuilder vs flask-login transitive dependency with > > click. They started to conflict once AppBuilder has released version > > 1.12.0. > > > > *Diagnosis:* > > Transitive dependencies with "flexible" versions (where >= is used > instead > > of ==) is a reason for "dependency hell". We will sooner or later hit > other > > cases where not fixed dependencies cause similar problems with other > > transitive dependencies. We need to fix-pin them. This causes problems > for > > both - released versions (cause they stop to work!) and for development > > (cause they break master builds in TravisCI and prevent people from > > installing development environment from the scratch. > > > > *Solution:* > > > > - Following the old-but-good post > > https://nvie.com/posts/pin-your-packages/ we are going to fix the > > pinned > > dependencies to specific versions (so basically all dependencies are > > "fixed"). > > - We will introduce mechanism to be able to upgrade dependencies with > > pip-tools (https://github.com/jazzband/pip-tools). We might also > take a > > look at pipenv: https://pipenv.readthedocs.io/en/latest/ > > - People who would like to upgrade some dependencies for their PRs > will > > still be able to do it - but such upgrades will be in their PR thus > they > > will go through TravisCI tests and they will also have to be specified > > with > > pinned fixed versions (==). This should be part of review process to > > make > > sure new/changed requirements are pinned. > > - In release process there will be a point where an upgrade will be > > attempted for all requirements (using pip-tools) so that we are not > > stuck > > with older releases. This will be in controlled PR environment where > > there > > will be time to fix all dependencies without impacting others and > likely > > enough time to "vet" such changes (this can be done for alpha/beta > > releases > > for example). > > - As a side effect dependencies specification will become far simpler > > and straightforward. > > > > Happy to hear community comments to the proposal. I am happy to take a > lead > > on that, open JIRA issue and implement if this is something community is > > happy with. > > > > J. > > > > -- > > > > *Jarek Potiuk, Principal Software Engineer* > > Mobile: +48 660 796 129 > > >
