Remove non-dedicated logging options and command line arguments

[hawkowl]

This simplifies things in preparation for the integration of structured logging, namely:

• Removing the deprecated command line arguments (which survived a purge way back in 0.9.0)
• Removing the functionality of the obsolete log_file and verbose settings
• Cleaning up the amount of things that use sighups

[codecov]

Codecov Report

Merging #5678 into develop will decrease coverage by 0.54%.
The diff coverage is 0%.

@@             Coverage Diff             @@
##           develop    #5678      +/-   ##
===========================================
- Coverage    63.27%   62.73%   -0.55%     
===========================================
  Files          331      331              
  Lines        36058    36002      -56     
  Branches      5936     5923      -13     
===========================================
- Hits         22815    22585     -230     
- Misses       11611    11769     +158     
- Partials      1632     1648      +16

[codecov]

Codecov Report

Merging #5678 into develop will decrease coverage by 0.04%.
The diff coverage is 16.66%.

@@             Coverage Diff             @@
##           develop    #5678      +/-   ##
===========================================
- Coverage    63.27%   63.22%   -0.05%     
===========================================
  Files          331      331              
  Lines        36058    36005      -53     
  Branches      5936     5923      -13     
===========================================
- Hits         22815    22764      -51     
- Misses       11611    11615       +4     
+ Partials      1632     1626       -6

[richvdh]

I regularly use --no-redirect-stdio; in fact I think that redirecting stdio at the python level is a misfeature (see also #1539 (comment)). Please can it not go away?

[hawkowl]

@richvdh if we need to print to true stdout or stderr (say in a situation where the logger doesn't work, or we want to perform a core dump, or other things), we should use the sys.__stdout__ and sys.__stderr__ references, which always reference true stdout/stderr, and will not be caught by the logging system.

Allowing regular print() calls to go to true stdout can mess up many things, especially when the logs being output there is in a machine-readable format (JSON, etc). Unless we explicitly want true stdout (by using print("something went wrong!", file=sys.__stdout__, flush=True), everything should go through the logging system without exception -- especially considering that in a cloud environment (SHHS), the logging system will be primarily forwarding structured logs over TCP, and information going to stdout may not be caught by that if you don't have something like fluentd set up to capture Docker stdout (which we're doing, but not everyone might).

old

[richvdh]

lgtm. I'm sure we'll find someone who is traumatised by the removal of these options, but I guess that's a battle we'll have to resign ourselves to.

[richvdh]

nit: this is probably redundant, since it's the same as the root logger?

[ara4n]

lgtm. I'm sure we'll find someone who is traumatised by the removal of these options, but I guess that's a battle we'll have to resign ourselves to.

ftr, that was me, on discovering that my synapse had silently stopped logging a few months ago, which is a right pain in the ass.

please can we at least warn loudly (or break hard) when removing old config options.