Creating On-Chain Alerts with Tenderly

Creating On-Chain Alerts with Tenderly: A Comprehensive Guide

In an ever-evolving DeFi and smart contract ecosystem, anticipating critical on-chain events is paramount. Tenderly’s alerting system empowers developers, security teams, and protocols to respond instantly to anomalies—flash loan attacks, unexpectedly large token transfers, failed transactions, or gas spikes. This article provides a detailed, step-by-step walkthrough for building robust on-chain alerts using Tenderly.

Why On-Chain Alerts Matter

• Real-Time Monitoring: Proactively track critical operations without manual scanning.
• Risk Mitigation: Detect exploits, reentrancy attempts, or front-running attacks before they wreak havoc.
• Operational Efficiency: Automate incident notifications via webhooks, SMS, Email, Slack, or Discord.

Prerequisites

1. Setting Up Your Tenderly Environment

First, create a new project in Tenderly. Projects isolate monitoring, alerts, and simulations for each protocol or dApp.

1. Create a Project:
   // Navigate to Projects gt New Project
   Name: ‘MyDeFiProtocol’
   Network: ‘Ethereum Mainnet’
2. Obtain API Credentials:
   API Key: ‘TEND-abcdef1234567890’

2. Defining Alert Types

Tenderly supports multiple alert categories. Below is a summary:

3. Crafting an Event-Based Alert

Suppose you want to watch for large ERC-20 transfers (e.g., gt10,000 tokens). Tenderly will scan all blocks, decode transfer events, and trigger when conditions meet.

3.1 Retrieve ABI and Event Signature

Use Etherscan API to fetch the token’s ABI programmatically.

3.2 Configure Alert in Tenderly Dashboard

1. In your project, click Add Alert gt Event Trigger.
2. Parameters:
   Contract Address: ‘0x6b175474e89094c44da98b954eedeac495271d0f’
   ABI: [ …ABI JSON… ]
   Event Name: ‘Transfer’
   Condition: ‘value gt= 10000000000000000000000’ (10,000 tokens in wei)
3. Webhook Endpoint: e.g. ‘https://hooks.slack.com/services/T000/B000/XXXXXXXX’
4. Payload Template:
   {
   ‘text’: ‘Large transfer detected: from {{from}} to {{to}} amount {{value formatUnits(18)}} DAI’,
   ‘blocks’: [ { ‘type’: ‘section’, ‘text’: { ‘type’: ‘mrkdwn’, ‘text’: ‘View on Tenderly: ’ } } ]
   }

Toggle your alert ON and Tenderly will begin scanning new blocks for matching Transfer events.

4. Building a Balance Threshold Alert via API

For advanced setups or CI/CD pipelines, you can create alerts programmatically using Tenderly’s REST API.

4.1 API Endpoint Request Structure

Example JSON payload for a balance threshold:

Remember to set Authorization: Bearer TEND-abcdef… in headers.

5. Advanced Use Cases Best Practices

5.1 Chaining Alerts with Scripts

You can integrate alerts with automated remediation scripts. For instance, an AWS Lambda function triggered by a Tenderly webhook can execute a safe fallback transaction via a multisig.

5.2 Rate Limiting Deduplication

High-velocity chains may trigger dozens of similar events per block. Use Tenderly’s deduplication window to suppress repeated alerts within a time interval.

5.3 Simulations Prior to Notifications

Leverage Tenderly’s advanced forking and simulation engine. Before an alert is triggered, run a simulation to confirm the state transition and reduce false positives.

6. Troubleshooting Common Pitfalls

• Missing ABI Mismatch: Ensure your ABI matches the deployed contract. Even slight mismatches prevent event decoding.
• Incorrect Chain ID: Alerts won’t fire if chain_id is wrong (1 for Mainnet, 4 for Rinkeby, etc.).
• Webhook Failures: Check HTTP status codes implement retries and error logs in your endpoint.

7. Further Resources

• Tenderly Alerts Documentation
• Tenderly Observability Suite
• Etherscan API Reference