lambda-watchtower

lambda-watchtower is a script for monitoring one or several HTTP(S) endpoints with AWS Lambda. Logs are stored as AWS CloudWatch metrics.

Usage

lambda-watchtower supports the following event parameters:

{
  "targets": [
    {
      "url": "https://example.org",
      "name": "example.org", //Optional, defaults to url; Display name of the target
    },
	{
	  "name": "Mailserver SMTP port check",
	  "type": "port",
	  "hostname": "mailserver.example.org",
	  "port": 25
	}
  ],
  "namespace": "Watchtower", //Optional, defaults to "Watchtower"; CloudWatch namespace
  "timings": ["readable", "total"], Optional, defaults to ["readable", "total"]; Determine which timings are logged.
  "timeout": 2000 //Optional, defaults to 2000: Time in ms before requests are aborted
}

Supported Timings

The following timings are supported and can be logged by lambda-watchtower:

• lookup: Time between beginning of request and successful DNS lookup
• connect: Time between DNS lookup and TCP connect
• secureConnect: Time between TCP connect and completion of HTTPS handshake
• readable: Time between successfully establishing the connection (and HTTPS handshake) and first byte received
• close: Time between first byte and the end of the request
• total: Total time from the beginning to the end of the request

Setup

There is a detailed step-by-step guide explaining how to set up lambda-watchtower. Read the step-by-step instructions.

If you’re already familiar with AWS IAM and Lambda, here is the short version for you:

1. Create a new IAM Role for Lambda with PutMetricData permissions for CloudWatch
2. Create a new Lambda Function with the contents of index.js assign the IAM role created above to this function.
3. Create a new CloudWatch Event Rule of type schedule.
4. Select how often you would like to check your endpoints.
5. Add the new Lambda function as the target.
6. Configure the input of the target and select "Constant (JSON text)".
7. Put the configuration JSON (see Usage) in the input field.
8. Save everything and give it a few minutes. New CloudWatch metrics can take a little while to show up.

Contributing

Pull requests and issues for additional features are welcome.

License

lambda-watchtower is licensed under the terms of the MIT license. For further information, please refer to the LICENSE file.