Rails database migrations cleaner/archiver/squasher

db.rake

namespace :db do
  namespace :migrate do
    task archive: :environment do
      Rake::Task["db:migrate"].invoke

      expires_in = 90.days
      files = Dir.glob(Rails.root.join("db/migrate/*").to_s)
      files.each do |path|
        name = File.basename(path)
        timestamp, _ = name.split("_", 2)
        date = Time.zone.parse(timestamp)
        next if date.since(expires_in).future?

        puts "Archiving #{name}"
        if ENV["DRY_RUN"].blank?
          archive = File.open(Rails.root.join("db/migrate_archive.rb"), "a")
          archive.puts("# #{name}")
          archive.puts(File.read(path))
          archive.puts

          FileUtils.rm(path)
        end
      end

      Rake::Task["db:migrate"].invoke
    end
  end
end