Support additional environment variables

[ybiquitous]

Description

I suggest that Bugsnag would support extra environment variables in addition to BUGSNAG_API_KEY when we configure Bugsnag.

Issue

Currently, Bugsnag supports only the BUGSNAG_API_KEY environment variable:

bugsnag-ruby/lib/bugsnag/configuration.rb

Line 121 in c8d9f4e

self.api_key = ENV["BUGSNAG_API_KEY"]

On the other hand, the bugsnag-capistrano gem supports the following variables:

• BUGSNAG_API_KEY
• BUGSNAG_APP_VERSION
• BUGSNAG_BRANCH
• BUGSNAG_RELEASE_STAGE
• BUGSNAG_REVISION
• BUGSNAG_REPOSITORY

I think it's very useful if this bugsnag-ruby gem would support the environment variables for configuration as the above example.

Now, we need to set explicitly as follow, but this seems to be verbose:

Bugsnag.configure do |config|
  config.release_stage = ENV["BUGSNAG_RELEASE_STAGE"]
end

https://github.com/sider/runners/blob/52dd7fd8fd48e316f934a886276e350907d8f433/bin/runners#L17

Environment

Library versions:

 * bugsnag (6.12.2)

[mattdyoung]

Hi @ybiquitous

Thanks for your suggestion. We'll consider this as part of future improvements across our Ruby error reporting libraries.

[ybiquitous]

Thank you! I'm looking forward to it.