posthog-security-basicsClaude Skill

PostHog Security Basics

Overview

Security best practices for PostHog API keys, tokens, and access control.

Prerequisites

• PostHog SDK installed
• Understanding of environment variables
• Access to PostHog dashboard

Instructions

Step 1: Configure Environment Variables

# .env (NEVER commit to git)
POSTHOG_API_KEY=sk_live_***
POSTHOG_SECRET=***

# .gitignore
.env
.env.local
.env.*.local

Step 2: Implement Secret Rotation

# 1. Generate new key in PostHog dashboard
# 2. Update environment variable
export POSTHOG_API_KEY="new_key_here"

# 3. Verify new key works
curl -H "Authorization: Bearer ${POSTHOG_API_KEY}" \
  https://api.posthog.com/health

# 4. Revoke old key in dashboard

Step 3: Apply Least Privilege

Environment	Recommended Scopes
Development	read:*
Staging	read:*, write:limited
Production	Only required scopes

Output

• Secure API key storage
• Environment-specific access controls
• Audit logging enabled

Error Handling

Security Issue	Detection	Mitigation
Exposed API key	Git scanning	Rotate immediately
Excessive scopes	Audit logs	Reduce permissions
Missing rotation	Key age check	Schedule rotation

Examples

Service Account Pattern

const clients = {
  reader: new PostHogClient({
    apiKey: process.env.POSTHOG_READ_KEY,
  }),
  writer: new PostHogClient({
    apiKey: process.env.POSTHOG_WRITE_KEY,
  }),
};

Webhook Signature Verification

import crypto from 'crypto';

function verifyWebhookSignature(
  payload: string, signature: string, secret: string
): boolean {
  const expected = crypto.createHmac('sha256', secret).update(payload).digest('hex');
  return crypto.timingSafeEqual(Buffer.from(signature), Buffer.from(expected));
}

Security Checklist

• API keys in environment variables
• .env files in .gitignore
• Different keys for dev/staging/prod
• Minimal scopes per environment
• Webhook signatures validated
• Audit logging enabled

Audit Logging

interface AuditEntry {
  timestamp: Date;
  action: string;
  userId: string;
  resource: string;
  result: 'success' | 'failure';
  metadata?: Record<string, any>;
}

async function auditLog(entry: Omit<AuditEntry, 'timestamp'>): Promise<void> {
  const log: AuditEntry = { ...entry, timestamp: new Date() };

  // Log to PostHog analytics
  await posthogClient.track('audit', log);

  // Also log locally for compliance
  console.log('[AUDIT]', JSON.stringify(log));
}

// Usage
await auditLog({
  action: 'posthog.api.call',
  userId: currentUser.id,
  resource: '/v1/resource',
  result: 'success',
});

Resources

• PostHog Security Guide
• PostHog API Scopes

Next Steps

For production deployment, see posthog-prod-checklist.