SaferRedis

SaferRedis wraps a Redis connection, and warns you before letting through commands that could impact production availability by being marked @slow or @dangerous in the Redis documentation. It's intended to be activated in production rails console sessions, and perhaps one-off scripts or Rake tasks, but not for handling production workload.

Inspiration is taken from https://github.com/ankane/strong_migrations which provides similar guard-rails for potentially dangerous database migrations.

Special cases

Commands tagged as @slow but with only O(1) complexity are not considered dangerous. This includes e.g. the extremely commonly used SET command.

The DEL command (@slow) is treated as UNLINK (@fast) when the lazyfree-lazy-user-del server option is set.

Limitations

Currently SaferRedis works with the redis gem from https://github.com/redis/redis-rb (regardless of which connection adapter is being used, e.g. hiredis) by hooking into the private #send_command method which was introduced in v4.6.0. This isn't a stable API, so other interception strategies will be considered and may be added in future. Some Redis connectors/drivers support middleware, but others don't.

Some commands are documented at the subcommand level as multiple words (e.g. CLIENT LIST). SaferRedis currently only recognises commands documented at their top-level single word (e.g. DEL). Support for multi-word commands will be considered and may be added in future.

Installation

Install the gem and add to the application's Gemfile by executing:

$ bundle add safer_redis

If bundler is not being used to manage dependencies, install the gem by executing:

$ gem install safer_redis

Usage

SaferRedis.activate!

redis = Redis.new

redis.del("very-large-collection")

# SaferRedis::Danger: The DEL Redis command might be dangerous.
#
# https://redis.io/commands/del/
#
# ACL categories: @keyspace @write @slow
#
# Complexity: O(N) where N is the number of keys that will be removed. When a key to remove holds a value other than a string, the individual complexity for this key is O(M) where M is the number of elements in the list, set, sorted set or hash. Removing a single key that holds a string value is O(1).
#
# If you're sure this is okay, you can try again within `SaferRedis.really { ... }`

SaferRedis.really { redis.del("hello") }
# => 1

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/buildkite/safer_redis. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.

License

The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the SaferRedis project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.