🔒 Monitor SSL certificate expiry dates with Google Sheets & Slack alerts

⚡ 149 views · 🔒 SecOps & Security Automation

Description

> ⚠️ Notice:
> Community nodes like @custom-js/n8n-nodes-pdf-toolkit can only be installed on self-hosted instances of n8n.

Screenshot from 20250914 161153.png

This n8n workflow illustrates how to monitor and track SSL certificate expiration dates for any domain using the SSL Checker node from customJS. It automatically updates a Google Sheet with the number of days left until expiry and sends a Slack notification when certificates are about to expire.

What this workflow does

• Input a list of domains from Google Sheets.
• Check each domain’s SSL certificate details, including expiration date and days left.
• Update the Google Sheet with the latest SSL expiry information.
• Notify via Slack if any certificate is expiring soon (e.g., less than 8 days).

Requirements

• Self-hosted n8n instance.
• CustomJS API key for SSL checking.
• Google Sheets API credentials for reading/updating domain data.
• Slack API credentials (optional, for notifications).

Workflow Steps

1. Schedule Trigger

   • ⏰ Starts the workflow automatically (weekly by default, configurable).

2. Google Sheets (Read Rows)

   • 📄 Retrieves the list of domains from your Google Sheet.

3. SSL Checker (CustomJS node)

   • 🔐 Fetches SSL certificate details for each domain.
   • Returns JSON output with fields such as expires and daysLeft.

4. Google Sheets (Update Rows)

   • 📝 Updates the sheet with the current number of days left until certificate expiry.

5. Check Days Left Threshold (formerly “If” node)

   • ⚠️ Evaluates whether the certificate expires within the threshold (e.g., < 8 days).

6. Slack Node

   • 💬 Sends a notification message if a certificate is close to expiration.

   Example Slack alert message:

   ⏰ Reminder: SSL certificate of www.example.com 
   will expire in 7 days.

SSL Checker node JSON output

{
  "output": {
    "domain": "example.com",
    "valid": true,
    "expires": "2025-12-31T23:59:59.000Z",
    "issuer": "Let's Encrypt",
    "daysLeft": 5
  }
}

## 🔗 Nodes Used

Google Sheets, Slack, Schedule Trigger

## 📥 Import

Download [`workflow.json`](workflow.json) and import into n8n:
**Workflow menu → Import from File**

[📖 Importing guide](../../../docs/importing-templates.md) · [🔑 Credential setup](../../../docs/credential-setup.md)