The Slack Chat Bot is a serverless, event-driven bot designed using the OpenWhisk open source project.

This bot is designed to post slack messages to OpenWhisk dev list (dev@openwhisk.incubator.apache.org) on a daily basis so that OpenWhisk developers receives a daily digest of conversations, one digest per slack channel. A daily digest will bring one whole day worth of updates in a single email on dev list and are archived on dev list for reference purposes. A daily digest contains filtered and formatted slack messages in easy to read and searchable format. The messages like someone joining a channel or leaving the channel, status updates, etc are filtered to create a meaningful and concise digest.

Proposed Architecture

The Slack Chat Bot is designed with a sequence of three dependent actions (like microservices) which is invoked by an internal OpenWhisk alarm trigger (similar to a cron job). Here is what action sequence does with its triggered flow.

Invoked once a day by an Alarm Trigger

The sequence of actions is invoked by Alarm trigger, which then starts a chain of microservices to retrieve slack history, filter and format the slack history, and compose email message which is sent to OpenWhisk dev list.

• Retrieve Slack History - An action that is invoked every 24 hours with OpenWhisk slack domain and a particular channel, retrieves a bunch of messages and user map. It then replaces user ID with user name in all the slack messages and sends them to next action in sequence. For example, user ID "XYZ" is replaced with username "bob":
  
  

   {
        "type": "message",
        "user": "XYZ",
        "text": "Did my email about Slack made it to the dev list?",
        "ts": "1484957540.000002"
    },

• Format Slack History -  An action invoked by retrieve slack history action. It takes a list of slack messages and drops messages with "subtype" of "channel_join". It runs messages through message builder for basic formatting and some advanced restructuring of messages including grouping parent messages and replies together.  

• Send Email to Dev List - An action invoked by format slack history action, receives formatted slack messages and sends email to dev list.