local_user is nil in CircleCI

[mochizukikotaro]

Hi!
I used capistrano-slackify in CircleCI 2.0, and encountered below error.

00:00 slack:notify_failed
      Notifying Slack of deploy failed
bundler: failed to load command: cap (/home/circleci/repo/vendor/bundle/ruby/2.4.0/bin/cap)
NoMethodError: undefined method `strip' for nil:NilClass

https://github.com/onthebeach/capistrano-slackify/blob/master/lib/capistrano/tasks/slackify.cap#L64

In CircleCI, local_user is nil.
So, I added Environment Variable USER in CircleCI. But it was difficult to notice this cause.

I am thinking of a pull request like below,

capistrano-slackify/lib/capistrano/tasks/slackify.cap

- set :slack_user, -> { local_user.strip }
+ set :slack_user, -> { local_user.to_s.strip }

what do you think about it? Please tell me any other good ideas.
Thanks!

[seenmyfate]

Hi @mochizukikotaro, thanks for the report - that would be a good approach for me. Capistrano sets this value to ENV["USER"] || ENV["LOGNAME"] || ENV["USERNAME"] if it hasn't been explicitly set, so treating it always as string here seems like something that would inevitably trip us up at some point.

[mochizukikotaro]

Hi @seenmyfate, thanks!
I made pull request. #35

[seenmyfate]

@mochizukikotaro thanks for the quick turn around! This is now available on Rubygems as v2.10.1