git_tag_cleanup.rb

# Script to delete all but a specified list of tags
# from a git repo, both locally and remotely
# Run like `mode=test ruby git_tag_cleanup` to test;
# use 'execute' mode to actually delete the tags

mode = ENV['mode'] || 'test'

tags_to_keep = %w[v2.0.0 v2.0.1]
tags_to_delete = `git tag`.split("\n") - tags_to_keep

puts "Keeping:  #{tags_to_keep.inspect}"
puts "Deleting: #{tags_to_delete.inspect}"

puts ""
puts mode == 'execute' ? "Executing!" : "NOT executing - test only"

tags_to_delete.each do |tag|
  delete_locally = "git tag -d '#{tag}'"
  delete_remote  = "git push origin :'#{tag}'"
  puts delete_locally      # to verify output
  system(delete_locally) if mode == 'execute'
  puts delete_remote
  system(delete_remote)  if mode == 'execute'
end

puts "\nDone! Tags remaining are:"
puts `git tag`