Hubots Service Discovery

hubot-service-discovery is a hubot service discovery service with built-in load balancing to horizontally scale Hubot instances.

This module is a Hubot Adapter. If you npm install it, you would start a Hubot instance with -a @hubot-friends/hubot-service-discovery and it will connect to a Hubot Service Discovery Server, register itself, and listen for incoming messages. The term "Adapter" here is just the fact that this connection utlizes Hubot's Adapter design – technically speaking. So in this part of the setup, a Hubot Service Discovery Server is the message input and the Hubot Worker connects to it for it's source of messages.

At this point, there's no running Hubot Service Discovery Server, so this worker does nothing until a Hubot Service Discovery Server is started and getting messages from the Chat app. Referring to the right side of the diagram below, we've started a Hubot Worker # 1.

The next part of the design is the left side of the diagram above – the input.

This Hubot instance's role is the adapter to the chat platoform (e.g. Slack, MS Teams, Discord). You'll still start this instance with something like hubot -a @hubot-friends/hubot-discord because the chat platform is how users interact with Hubot – the input. But now, this Hubot instance won't have all you're command handling scripts; it'll have the Hubot script located in this package.

The steps to manually install this script is:

• npm i @hubot-friends/hubot-service-discovery

• Add hubot-service-discovery/DiscoveryService.mjs to your external-scripts.json file

  [ "hubot-service-discovery/DiscoveryService.mjs" ]

If you want to start from scratch:

• cd folder-to-have-mybot Probably use a different folder name

• npx hubot --create myhubot --adapter @hubot-friends/hubot-discord Pick your adapter. Just using Discord as an example here.

• cd myhubot

• npm i @hubot-friends/hubot-service-discovery

• Add hubot-service-discovery/DiscoveryService.mjs to your external-scripts.json file

  [ "hubot-service-discovery/DiscoveryService.mjs" ]

Now when you start the Hubot Adapter instance as shown in the diagram above, incoming chat messages will be routed through load balancing logic which picks a Hubot Worker to send the message to. This lets you scale Hubot horizontally across processes or servers while keeping the UX seamless.

This is the Hubot that has the chat app adapter (e.g. @hubot-friends/hubot-discord).

The key is that your external-scripts.json file contains the DiscoveryService.mjs script like so:

It's a little weird because this is the server but it's loaded as a Hubot script. That's because it's just intercepting messages from the Hubot Adapter that's connected to the chat app.

My assumption is that this is a Git repo that contains all of your Hubot scripts (i.e. in a folder called scripts).

NAME_OF_YOUR_HUBOT is the name you gave your Hubot instance that is connected to the chat app.

Say you're building a Discord bot with Hubot. You have a start task in your package.json file like so:

Starting the instance with:

sets the name of your Hubot. So when you're on Discord and you want to send your Hubot a message, you'd do it like (where name is mybot in this example), @mybot help.

You might have the name set in the start script like so:

In which case, you wouldn't need to include the -- --name ${NAME_OF_YOUR_HUBOT} becasue it's already set in the start task.

• HUBOT_SERVICE_NAME - Service name for registration (default: 'hubot')
• HUBOT_INSTANCE_ID - Unique instance identifier (default: generated as hubot-<Date.now()>)
• HUBOT_HOST - Host address for this instance (default: 'localhost')
• HUBOT_PORT - Port for this instance (default: 8080)
• HUBOT_HEARTBEAT_INTERVAL - Heartbeat interval in ms (default: 15000)
• HUBOT_DISCOVERY_PORT - Port for the discovery server (default: 3100)
• HUBOT_DISCOVERY_STORAGE - Storage directory for event store (default: ./data)
• HUBOT_DISCOVERY_TIMEOUT - Heartbeat timeout in ms (default: 30000)
• HUBOT_LB_STRATEGY - Load balancing strategy: round-robin, random, least-connections (default: round-robin)

• HUBOT_DISCOVERY_URL - URL of discovery server to connect to (e.g., 'ws://discovery-server:3100')
• HUBOT_INSTANCE_ID - Unique instance identifier (default: hubot-{Date.now()})
• HUBOT_HOST - Hostname (default: localhost)
• HUBOT_PORT - Port that the http server binds to (default: 8080)