github_labels_manager.rb

require 'octokit'

client = Octokit::Client.new login: 'username', password: 'password'

repos = []
page  = 1

loop do
  puts "Fetching repositories from page ##{page}"

  new_repos = client.organization_repositories('organization',
    type: :all,
    per_page: 100,
    page: page
  ).map(&:full_name)

  repos.concat(new_repos)

  if new_repos.count < 100
    break
  else
    page += 1
  end
end

puts "Total of repositories: #{repos.count}\n"

repos.each_with_index do |repo, index|
  print "Repo #{index + 1}/#{repos.count} - '#{repo}'..."

  print "\tRemoving current labels"
  client.labels(repo).each do |label|
    print '.'
    client.delete_label!(repo, label[:name])
  end

  labels = [
    { name: 'reviewed', color:'207de5' },
    { name: 'staging',  color:'fbca04' }
  ]

  print "\tCreating new labels\t"
  labels.each do |label|
    print '.'
    client.add_label(repo, label[:name], label[:color])
  end

  puts
end