Extract the Slack message history per channel for a time period

index.js

// Extract the Slack message history per channel for a time period
// Gives an idea which Slack channels are most used
// Usage:
//   Save SLACK_TOKEN in .env file
//   npm install
//   npm start | tee slack_channels.csv
const WebClient = require('@slack/client').WebClient;
const Promise = require('bluebird');
const moment = require('moment');

const token = process.env.SLACK_TOKEN;
if (!token) {
  console.error('Run with environment variable SLACK_TOKEN set to a token from https://api.slack.com/docs/oauth-test-tokens');
  process.exit(1);
}

const web = new WebClient(token);

// How many channels and users to fetch from Slack at a time
const channelsConcurrency = 4;
const userConcurrency = 4;
// How long ago to look back at messages
const messagesSince = moment().subtract(60, 'days').format('YYYY-MM-DD');

// Show or hide debug messages
const debug = false;
console.debug = debug ? console.log : () => {};

const channels = {};
const users = {};
const channelMembers = new Set();

// Fetch channels
console.debug('fetching channels');
web.channels.list({ exclude_archived: true }).then(info => {
  return Promise.map(info.channels, (channel) => {
    const id = channel.id;
    // Filter non-public channels
    if (id[0] !== 'C') {
      return;
    }
    // Save channel
    channels[channel.name] = {
      membersCount: channel.members.length,
      messageCount: {},
    };

    // Fetch user info for channel members
    console.debug(`fetching users for ${channel.name}`);
    return Promise.map(channel.members, (member) => {
      if (!users[member]) {
        users[member] = web.users.info(member).then(info => info.user);
      }

      return users[member];
    }, { concurrency: userConcurrency }).then((members) => {
      // Get message count by each user
      return Promise.map(members, (member) => {
        // Only count core members
        if (member.is_bot || member.is_restricted || member.deleted) {
          return;
        }

        const query = `in:${channel.name} after:${messagesSince} from:${member.name}`;
        console.debug(`getting message count ${query}`);
        return web.search.messages(query, { count: 0 }).then(info => {
          // Save message count and member info
          channelMembers.add(member.name);
          channels[channel.name].messageCount[member.name] = info.messages.total;
        });
      }, { concurrency: userConcurrency });
    });
  }, { concurrency: channelsConcurrency });
}).then(() => {
  // Display in CSV format
  const sortedMembers = [...channelMembers].sort();
  const sortedMembersList = sortedMembers.join(",");
  console.log(`channel,members,messages,${sortedMembersList}`);
  Object.keys(channels).forEach((channelName) => {
    const channel = channels[channelName];
    const membersCount = channel.membersCount;
    const totalMessageCount = Object.values(channel.messageCount).reduce((a, b) => (a || 0) + (b || 0), 0);
    const memberMessageCountList = sortedMembers.map((memberName) => channel.messageCount[memberName]).join(",");
    console.log(`${channelName},${membersCount},${totalMessageCount},${memberMessageCountList}`);
  });
});

package.json

{
  "name": "slack-channels",
  "version": "1.0.0",
  "description": "Extract the Slack message history per channel for a time period",
  "main": "index.js",
  "scripts": {
    "start": "env $(cat .env | xargs) node index.js"
  },
  "author": "Julien Vanier <jvanier@gmail.com>",
  "license": "MIT",
  "dependencies": {
    "@slack/client": "^3.10.0",
    "bluebird": "^3.5.0",
    "moment": "^2.18.1"
  }
}