Relax is a Message Broker for Slack Bots. What does that mean? If you are running a "bot-as-a-service" for Slack, you have to maintain hundreds (if not thousands) of websocket connections and handle the deluge of events from all these connections.

Relax does all that heavy lifting for you and provides you with a single stream of events that your web app can then take action on. The protocol is JSON based and so any web app can communicate with Relax.

If you are a Rails app however, there is a nifty Ruby client for you to use.

You can also download pre-built binaries here.

If you are a Heroku user, you can deploy Relax right away with one click.

Known Issue: When deploying using the "Deploy with Heroku" button, Heroku's Free Redis server takes a while to boot up, so your Relax deployment will take a while to come up as well. You can see Relax trying to connect to Heroku's Redis server by tailing logs heroku logs --tail -a <your-heroku-app-name>. After a while, it should connect.

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Although Relax is written in Go, it does not require any knowledge of Go. You can download the latest stable version of relax here.

Binaries are available for both OS X and Linux. Untar and gunzip the downloaded file and move the relax binary to your $PATH to start using.

Relax is used in production to power Nestor.

To run it, basically run relax (assuming it is in your $PATH).

RELAX_BOTS_KEY=relax_bots_key RELAX_BOTS_PUBSUB=relax_bots_pubsub RELAX_EVENTS_QUEUE=relax_events_queue REDIS_HOST=localhost:6379 relax

The Relax message broker requires a few environment variables to be set up (these same environment variables are also used to set up the Relax Ruby Client). These environment variables are basically Redis keys that can be configured based on your specific needs.

RELAX_BOTS_KEY: This can be any string value and is used to store state about all Slack clients currently controlled by Relax in Redis.

RELAX_BOTS_PUBSUB: This can be any string value and is used by Relax clients to notify Relax brokers that a new Slack bot has been started.

RELAX_EVENTS_QUEUE: This can be any string value and is used by Relax brokers to send events to the client.

RELAX_MUTEX_KEY: This can be any string value and is used by Relax brokers to decide whether to send events back to clients.

You interact with Relax by sending messages to Relax via Redis, there are two primary ways of interacting with Relax:

To start a bot, you need to HSET on REDIS_BOTS_KEY with a JSON blob containing "team_id" and "token" keys which represent the Team UID and Token for the bot you want to start. Along with this, you should also PUBLISH on REDIS_BOTS_PUBSUB with a JSON blob containing the keys "type" and "team_id" containing the values "team_added" and the Team UID of the bot you want to start.

For e.g., for a bot who's Slack Team UID is "TDEADBEEF" and who's token is "xoxo_slackbotoken", you can issue the following commands using redis-cli to start a bot (assuming that $REDIS_BOTS_KEY is redis_bots_key):

$ redis-cli
127.0.0.1:6379> MULTI
OK
127.0.0.1:6379> HSET redis_bots_key TDEADBEEF '{"team_id":"TDEADBEEF","token":"xoxo_slackbotoken"}'
(integer) 1
127.0.0.1:6379> HGETALL redis_bots_key
1) "TDEADBEEF"
2) "{\"team_id\":\"TDEADBEEF\",\"token\":\"xoxo_slackbotoken\"}"
127.0.0.1:6379> PUBLISH redis_bots_pubsub '{"type":"team_added","team_id":"TDEADBEEF"}'
QUEUED
127.0.0.1:6379> EXEC

Relax also generates events (details of events are described in the "Events" section of the README)

Events are queued in the $REDIS_EVENTS_QUEUE key in Redis and so to consume events, you need to LPOP or BLPOP the $REDIS_EVENTS_QUEUE to deal with events.

Slack Events are gathered from all teams that Slack is listening to and are multiplexed onto a single Redis queue. The event data structure consists of the following fields:

This is a string value contains the type of event can hold the following values:

This is a string value and is the UID (generated by Slack) of the user associated with the event. So in the case of message_new it's the UID of the user who created the message, for reaction_added, it's the UID of the user who added a reaction to a message.

This is the UID (generated by Slack) of the channel associated with the event.

This is a boolean value to indicate whether the channel (with the UID channel_uid) is an IM or not.

This is a string value and contains the text associated with the event. This can mean different things in different contexts:

This is a string value and represent the UID of the bot that Relax controls. This is useful if you want to strip out the @-mention word in a message @-mention'ed to the bot.

This is a string value and represents the timestamp at which a particular event occurred but can have different meanings in different contexts:

This is a string value and until Relax supports multiple providers, this is always "slack".

This is a string value and represents the time at which an event occurs. In the case of disable_bot, team_join and im_created events, it is an empty string.