[packaging] move list of python project from requirements.txt into install_requires in setup.py

[mbukatov]

This issue suggest to remove requirements.txt file and move items which this file contains into install_requires setuptools keyword in setup.py file.

Reasoning

Based on explanation of difference between install_requires keyword and requirements.txt file from upstream Python Packaging User Guide, I understand that:

• python project should provide minimal abstract list of projects which are needed to run it correctly in install_requires
• requirements.txt files are used to define the requirements for a complete python environment

Since this project is a single Tendrl component, which is expected to be installed with other Tendrl components together, using requirement file seems to be inappropriate. Listing dependencies of single reusable python library/tool/daemon, which is our case here, is not mentioned among 4 common uses of Requirements files as listed in description of the feature in packaging guide. Moreover, it creates additional issues:

• using requirements.txt file makes us to install the project in non-production way, which means that we will find problems with listing requirements later than we should, see eg. issue [packaging] setup.py doesn't contain list of requirements #17 - this is very blatant issue, but was not noticed by any developer, unit tests or CI - since all of those are using installation method which doesn't resemble what an admin using this project would do
• keeping requirements.txt file while specifying install_requires in setup.py requires to maintain function to read requirements.txt file in setup.py, which is unnecessary maintenance burden
• feature set of requirements.txt is higher and includes features which should not be done in production setup

[mbukatov]

Issues of the same kind were created in all other Tendrl components written in python:

• https://github.com/Tendrl/performance_monitoring/issues/18
• [packaging] move list of python project from requirements.txt into install_requires in setup.py node-agent#118
• [packaging] move list of python project from requirements.txt into install_requires in setup.py ceph-integration#70
• [packaging] move list of python project from requirements.txt into install_requires in setup.py gluster-integration#98
• [packaging] move list of python project from requirements.txt into install_requires in setup.py commons#88

[r0h4n]

We are using "install_requires" in setup.py, Contents of the requirements.txt are automatically extracted and fed to "install_requires" [0], currently the performance_monitoring and alerting projects do not address that, @anmolbabu please refer to setup.py [0]

0 : https://github.com/Tendrl/node_agent/blob/master/setup.py#L25

[mbukatov]

@r0h4n my point here is that I would rather not use requirements.txt file at all, and use install_requires in setup.py only - does this make sense for you?

[mbukatov]

This topic was discussed on a meeting today, the summary follows:

• the current dev work flow uses pip freeze to generate requirements.txt file on purpose
• we agreed to keep requirements.txt files as primary and the only source of requirements (install_requires in setup.py is defined based on content of this file)
• we agreed to drop explicit usage of pip install -r requirements.txt from CI configuration (eg. tox.ini), so that the connection between requirements.txt and install_requires is checked early

I'm going to propose a pull request witch tox.ini configuration change for the last point.

[mbukatov]

Based on agreement described in #18 (comment) (keep requirements.txt file), I'm closing this issue.

Btw: Issue with missing installation requirements in setup.py is tracked in #17

[mbukatov]

After checking how tox.ini and travis are wired up during work on #24, I feel that we should not maintain requirements via pip freeze generated requirements.txt file.