Jbee - codehooks.io

Posted on Dec 14

Build a Slack Bot with This Webhook Template

#webhooks #slackbot #javascript #serverless

Ever wanted to build a Slack bot but got overwhelmed by the setup complexity? This minimal webhook template gets you a secure, production-ready Slack webhook handler with just a few commands.

The Template

Did you know there's a minimal Slack webhook template for Codehooks.io that makes it ridiculously easy to start building Slack integrations? Here's what makes it great:

~90 lines of code - No bloat, easy to understand
Secure by default - HMAC SHA-256 signature verification built-in
Production-ready - Handles URL verification, signature validation, and timing attacks
Serverless - No servers to manage, auto-scales

Getting Started

coho create myapp --template webhook-slack-minimal
cd myapp
npm install
coho deploy

That's it. Three commands. Your webhook is live.

What You Get Out of the Box

The template handles all the boring security stuff for you:

// Automatic signature verification
function verifySlackSignature(body, signature, timestamp) {
  // Rejects requests older than 5 minutes
  // Uses timing-safe comparison
  // Validates HMAC SHA-256 signature
}

// URL verification for Slack setup
if (body.type === 'url_verification') {
  return res.json({ challenge: body.challenge });
}

// Your bot logic starts here
if (event.type === 'message' && !event.bot_id && event.text) {
  console.log('Message:', event.text);
  // Do something cool
}

Just add your SLACK_SIGNING_SECRET environment variable, point Slack at your webhook URL, and you're receiving events.

Cool Use Cases

Here are some practical ways teams are using Slack bots:

1. Incident Response Bot

Automatically create tickets and notify on-call engineers when someone types @bot incident in your #alerts channel. Parse the message, extract severity levels, and kick off your incident management workflow. Integrate with PagerDuty, Jira, or your internal tools.

if (event.text.includes('incident')) {
  // Parse incident details
  // Create ticket in your system
  // Page on-call engineer
  // Post confirmation back to channel
}

2. Code Review Reminder Bot

Monitor your #engineering channel and remind developers about pending code reviews. When someone mentions a PR link, the bot tracks it and sends daily reminders until it's merged. Integrates with GitHub/GitLab APIs to check PR status.

if (event.text.includes('github.com') && event.text.includes('/pull/')) {
  // Extract PR URL
  // Check PR status via GitHub API
  // Schedule reminders for reviewers
  // Update team when merged
}

3. Knowledge Base Assistant

Create a smart assistant that answers common questions by searching your internal docs. Team members can ask @bot how do I deploy? and get instant answers with links to relevant documentation. Saves your team from answering the same questions repeatedly.

if (event.text.includes('@bot')) {
  const query = extractQuery(event.text);
  // Search your knowledge base
  // Format relevant results
  // Post back with helpful links
}

Why This Matters

Most Slack bot tutorials leave you wading through authentication flows, webhook verification logic, and security best practices. This template gives you that foundation in ~90 lines, so you can focus on building the actual bot logic.

The Codehooks.io platform handles deployment, scaling, environment variables, and logging. You just write JavaScript and deploy.

Next Steps

The template is minimal on purpose - it's designed to be extended. Here's what you might add:

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