Environment variable configuration changes

[heyman]

• Automatically generate documentation for all available environment variables when documentation is built.
• Explicitly set environment variable names for the command line options.
• Rename env variables LOCUST_MASTER, LOCUST_MASTER_PORT in order to make it less likely that they collide with env vars automatically added by Kubernetes. Also change the name of LOCUST_WORKER and LOCUST_MASTER_HOST for consistency.
• Rename env variable CSVFILEBASE to LOCUST_CSV.
• Remove --csv-base-name command line option.¨
• Removed some redundant comments

[codecov]

Codecov Report

Merging #1355 into master will not change coverage.
The diff coverage is 0.00%.

@@           Coverage Diff           @@
##           master    #1355   +/-   ##
=======================================
  Coverage   80.69%   80.69%           
=======================================
  Files          24       24           
  Lines        2258     2258           
  Branches      346      346           
=======================================
  Hits         1822     1822           
  Misses        344      344           
  Partials       92       92           

Impacted Files	Coverage Δ
locust/argument_parser.py	74.31% <ø> (ø)
locust/main.py	20.00% <0.00%> (ø)

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[cyberw]

Lgtm. I still prefer auto env vars, but it is not a big thing for me. I also slightly prefer the csv option to be stored as csv and not csv_prefix, but no biggie

You can probably remove the warning I added previously (the one that looks for K8s env vars). I’m on mobile so I cant find the specific file :)

[heyman]

I also slightly prefer the csv option to be stored as csv and not csv_prefix, but no biggie

The argument is still --csv. The only reason I changed the dest param to be csv_prefix was that I think the following help text:

  --csv CSV_PREFIX  Store current request stats to files in CSV format. Setting this option
                    will generate three files: [CSV_PREFIX]_stats.csv,
                    [CSV_PREFIX]_stats_history.csv and [CSV_PREFIX]_failures.csv

is slightly better than:

  --csv CSV      Store current request stats to files in CSV format. Setting this option
                 will generate three files: [CSV]_stats.csv,
                 [CSV]_stats_history.csv and [CSV]_failures.csv

(in the second help text there's a risk of confusion due to the "files in CSV format" string in the first sentence)

[cyberw]

Ok!