Add bisect_gemfile_parser script

[NickLaMuro]

This is a helper for running a bisect when having to deal with "point in time" issues when bisecting and dealing with git-gems

Because our Gemfile use the most recent version of the gem when running a bundle and/or bundle update, when attempting to do a git bistect, dependecies that might be causing the issue are not being checked out in a fashion that represents what the state of things were in the MIQ environment at the point of the checkout.

This helper attempts to checkout a proper revision of all of the manageiq git gem dependencies by checking the current revision of the gems in the currently parse Gemfile, and throws a override file in the bundler.d/ directory which will set the proper overrides.

Usage

The workflow for using this script is as follows;

1. Start git bisect
2. Run the script
   • you can actually chuck this in bin/ since it is git-ignored)
3. Run bin/bundle update
4. Do what you need to validate the git sha, and move on the the next commit
5. Repeat steps 2-4 until you are finished
6. Run rm bundle.d/bisect.rb to clean up this script (DON'T FORGET!)

The last step is important as it will most likely mess with your your master branch.

Example Output

Here is an example bundle.d/bisect.rb output for a given run:

require "shellwords"
require "time"

class Bundler::Source::Git::GitProxy
  private

  def find_local_revision
    allowed_in_path do
      if ref.include?("@")
        branch, timestamp = ref.split("@")
        git("log --format='%H' --before=#{timestamp.gsub(/[\{\}]/,"")} --merges -n1 #{branch}").strip
      else
        git("rev-parse --verify #{Shellwords.shellescape(ref)}", true).strip
      end
    end
  end
end

bisect_iso_time = `git show -q --format="%ai"`.chomp
# Time in "hours ago".
#   example:  "100.hours.ago"
bisect_time = "#{(Time.now.to_i - Time.parse(bisect_iso_time).to_i) / 60 / 60}.hours.ago"

override_gem 'manageiq-gems-pending', :git => 'https://github.com/ManageIQ/manageiq-gems-pending', :ref => "fine@{#{bisect_time}}"
override_gem 'manageiq-content', :git => 'https://github.com/ManageIQ/manageiq-content', :ref => "fine@{#{bisect_time}}"
override_gem 'manageiq-providers-amazon', :git => 'https://github.com/ManageIQ/manageiq-providers-amazon', :ref => "fine@{#{bisect_time}}"
override_gem 'manageiq-providers-azure', :git => 'https://github.com/ManageIQ/manageiq-providers-azure', :ref => "fine@{#{bisect_time}}"
override_gem 'manageiq-providers-vmware', :git => 'https://github.com/ManageIQ/manageiq-providers-vmware', :ref => "fine@{#{bisect_time}}"
override_gem 'manageiq-ui-classic', :git => 'https://github.com/ManageIQ/manageiq-ui-classic', :ref => "fine@{#{bisect_time}}"
override_gem 'manageiq-providers-lenovo', :git => 'https://github.com/ManageIQ/manageiq-providers-lenovo', :ref => "fine@{#{bisect_time}}"

TODO

• Consider searching for "merge commits" only in the versus any old commit (those are the only ones that matter)
• Possibly add workflow commands for handling bistect commands, that will run both steps 2 & 3 from the above workflow
• Possibly add a bisect_gemfile_parser cleanup subcommand to handle the rm bundler.d/bisect.rb portion of things.

[NickLaMuro]

Not sure if I will commit this now, or do the TODO's as part of this PR, but wanted to get this off of my machine as I am now finding a use for it again.

[kbrock]

still not 100% show to use but it looks cool

[kbrock]

you use branch up above, can you use that same thing here?

[NickLaMuro]

What I am thinking for this is I would probably use --branch flag to allow you to change the branch. I think the branch you are referring to is the from parsing the master@ part, so that would be coming from this line.

I am sure there are ways to "git" it from git itself, but chances are you would be bisecting this from a specific branch anyway, so a flag is probably okay to use and just default it to master otherwise.

[NickLaMuro]

still not 100% show to use but it looks cool

@kbrock Grammatical errors aside, what can I improve to make this easier to use? Tried to include some documentation in the script itself (which is just what I ended up using for the PR description), but wouldn't mind hearing suggestions on what I can do to make this more clear.