Support Debian Buster and MariaDB

[CaptainSifff]

Curerntly the debian scripts prevent a build on Debian Buster.
Among the notable changes are:

• Debian Buster ships mariadb instead of mysql, hence some package names have changed
• Python-3.7 is the default.

[coveralls]

Coverage increased (+0.07%) to 84.549% when pulling 1b8a520 on CaptainSifff:ng into 398e470 on allegro:ng.

[romcheg]

@CaptainSifff Ralph is not tested against python-3.7 and MariaDB and most likely the tests will fail. Could you please verify this?

[CaptainSifff]

Sure, I can check. does ralphctl expose some kind of testsuite?
I had to fiddle a bit with the package version in requirements.txt (rq >= 0.12 and django-rq >= 1.2.0)
But so far, I found that I can populate the database with the demo data and play with
that dataset through the browser without noticing any issues so far.

[CaptainSifff]

I tested some of the ralphctl commands:
ralphctl demodata: seems to work - database is populated and looks like I think it is expected.
ralphctl sqlflush - lots of output, no error
ralphctl ldap_sync - fails, currently not built with ldap(comes next)
ralphctl push_graphs_to_statd - no output, no error
ralphctl check - System check identified no issues (0 silenced).
ralphctl compilemessages - no error
ralphctl createcachetable - no error, no output
ralphctl dbshell - Mariadb shell preset to the ralph_ng database
ralphctl shell - Python3.7 shell
ralphctl test - Creating test database for alias 'default'...
Got an error creating the test database: (1044, "Access denied for user 'ralph_ng'@'localhost' to database 'test_ralph_ng'")
Which is expected that In the spirit of the installation docs I only gave permission to acces the database ralph_ng
ralphctl rqstats - Connection refused, somehow expected since I didn't set up redis

Anything else that you are interested in?

[CaptainSifff]

I also got ldap and openldap sufficiently working for my needs by following the steps from the doc:
https://ralph-ng.readthedocs.io/en/latest/installation/configuration/
I also needed the patch from #3080 for patching ldap.py and the documentation given in
#3077 for patching prod.py.

[romcheg]

@CaptainSifff thank you for the research you have made. Before we start shipping the package for debian, we should enable automatic tests for 3.7 and mariadb. A spare pair of hands (you :) ) would be helpful for that atm. Let's discuss details in our Gitter channel.

[romcheg]

Left a few comments inline. Could you also please change mysql to mysql/mariadb in the debconf? You may want to test that after introducing the changes -- to do that build the package using make build-snapshot-package command and then install the package somewhere.

[CaptainSifff]

I also modified now the template as pointed out by @romcheg so that mariadb should be a possibility.

[vi4m]

@romcheg Do we wait for something here? is it RTM?

[romcheg]

@vi4m the changes do not allow to build the package for Buster within the existing build scripts, so we cannot merge this.

[CaptainSifff]

Can somebody remind me what I would have to check...? The pipeline still goes through or did I miss a point?