Subscribe to Redis HSET events

sub.rb

require 'redis'

redis = Redis.new

redis.config(:set, 'notify-keyspace-events', 'Eh')

redis.psubscribe('__keyevent@*__:hset') do |on|
  on.pmessage do |_pattern, _channel, hash_key|
    puts "Hash #{hash_key} has been updated."
  end
end