Migrate Sidekiq Redis

migrate-sidekiq-redis.rb

# A script to migrate Sidekiq's redis to a new server.
# This obviously can work for any redis, but I only handled
# data types that Sidekiq uses.

require 'redis'

old_redis = Redis.new url: 'redis://old-redis:6379'
new_redis = Redis.new url: 'redis://new-redis:6379'

unknowns = []

old_redis.keys('*').each do |key| 
  puts key

  case old_redis.type(key)
  when 'string'
    new_redis.set(key, old_redis.get(key))
  when 'hash'
    new_redis.mapped_hmset(key, old_redis.hgetall(key))
  when 'zset'
    new_members = old_redis.zrange(key, 0, -1, with_scores: true).map { |m, s| [s, m] }
    new_redis.zadd(key, new_members)
  when 'set'
    new_redis.sadd(key, *old_redis.smembers(key))
  else
    unknowns << key
  end

  ttl = old_redis.ttl(key)
  new_redis.expire(key, ttl) if ttl > 0
end

puts "Unknown Keys: #{unknowns.inspect}" if unknowns.any?