gitlab-foss/scripts/feature_flags/used-feature-flags

#!/usr/bin/env ruby
# frozen_string_literal: true

require 'fileutils'
require_relative '../../lib/gitlab_edition'

ADDITIONAL_EDITIONS = %w[ee jh].freeze

class String
  def red
    "\e[31m#{self}\e[0m"
  end

  def yellow
    "\e[33m#{self}\e[0m"
  end

  def green
    "\e[32m#{self}\e[0m"
  end

  def bold
    "\e[1m#{self}\e[0m"
  end
end

def add_definition_path!(edition, flag_def_paths)
  return unless GitlabEdition.public_send(:"#{edition}?") # rubocop:disable GitlabSecurity/PublicSend

  flag_def_paths << "#{edition}/config/feature_flags/**/*.yml"
end

def mark_replicator_flags_as_used(edition)
  return unless GitlabEdition.public_send(:"#{edition}?") # rubocop:disable GitlabSecurity/PublicSend

  # Geo feature flags are constructed dynamically and there's no explicit checks in the codebase so we mark all
  # the replicators' derived feature flags as used.
  # See https://gitlab.com/gitlab-org/gitlab/-/blob/54e802e8fe76b6f93656d75ef9b566bf57b60f41/ee/lib/gitlab/geo/replicator.rb#L183-185
  geo_feature_flag_suffixes = %w[replication force_primary_checksumming]

  Dir.glob("#{edition}/app/replicators/geo/*_replicator.rb").each do |path|
    replicator_name = File.basename(path, '.rb')

    geo_feature_flag_suffixes.each do |suffix|
      feature_flag_name = "geo_#{replicator_name.delete_suffix('_replicator')}_#{suffix}"
      FileUtils.touch(File.join('tmp', 'feature_flags', "#{feature_flag_name}.used"))
    end
  end
end

flag_definition_paths = [
  'config/feature_flags/**/*.yml'
]

ADDITIONAL_EDITIONS.each do |edition|
  add_definition_path!(edition, flag_definition_paths)
  mark_replicator_flags_as_used(edition)
end

all_flags = {}
additional_flags = Set.new

# Iterate all defined feature flags
# to discover which were used
Dir.glob(flag_definition_paths).each do |flag_definition_path|
  feature_flag_name = File.basename(flag_definition_path, '.yml')

  # TODO: we need a better way of tracking use of Gitaly FF across Gitaly and GitLab
  if feature_flag_name.start_with?('gitaly_')
    puts "Skipping the #{feature_flag_name} feature flag since it starts with 'gitaly_'."
    next
  end

  all_flags[feature_flag_name] = File.exist?(File.join('tmp', 'feature_flags', "#{feature_flag_name}.used"))
end

# Iterate all used feature flags
# to discover which flags are undefined
Dir.glob('tmp/feature_flags/*.used').each do |path|
  feature_flag_name = File.basename(path, '.used')

  additional_flags.add(feature_flag_name) unless all_flags[feature_flag_name]
end

used_flags = all_flags.select { |_name, used| used }
unused_flags = all_flags.reject { |_name, used| used }

puts "=========================================".green.bold
puts "Feature Flags usage summary:".green.bold
puts

puts "- #{all_flags.count + additional_flags.count} was found"
puts "- #{unused_flags.count} appear(s) to be UNUSED".yellow
puts "- #{additional_flags.count} appear(s) to be unknown".yellow
puts "- #{used_flags.count} appear(s) to be used".green
puts

if additional_flags.count > 0
  puts "==================================================".green.bold
  puts "There are feature flags that appear to be unknown".yellow
  puts
  puts "They appear to be used by CI, but we do lack their YAML definition".yellow
  puts "This is likely expected, so feel free to ignore that list:".yellow
  puts
  additional_flags.sort.each do |name|
    puts "- #{name}".yellow
  end
  puts
end

if unused_flags.count > 0
  puts "========================================".green.bold
  puts "These feature flags appear to be UNUSED".red.bold
  puts
  puts "If they are really no longer needed REMOVE their .yml definition".red
  puts "If they are needed you need to ENSURE that their usage is covered with specs to continue.".red
  puts "Feature flag usage is detected via Rubocop, which is unable to resolve dynamic feature flag usage,".red.bold
  puts "interpolated strings however are optimistically matched. For more details consult test suite:".red
  puts "https://gitlab.com/gitlab-org/gitlab/-/blob/69cb5d36db95881b495966c95655672cfb816f62/spec/rubocop/cop/gitlab/mark_used_feature_flags_spec.rb".red
  puts
  unused_flags.keys.sort.each do |name|
    puts "- #{name}".yellow
  end
  puts
  puts "Feature flag usage check failed.".red.bold
  exit(1)
end

puts "Everything is fine here!".green
puts