This project contains AWS Lambda code that monitors a configured webpage. It queries the webpage for a desired status and, if that status is found, will send a text message to the configured number.
A query function is
provided to the monitor that should return the piece of interest in the webpage. A checker function is also
provided that accepts the result from the query function and returns a boolean. If this function returns true,
then When a website has a supply of the item being monitored, it sends a text message to the configured number.
A simple class is provided at lib/Monitor.js. This class contains one method, Monitor.check, which is what
is directly called by the Lambda.
When instantiating the class, it requires an object with three properties: url, queryFunction, and
checkStatus.
url is the URL of the webpage to monitor.
queryFunction is a function that accepts $, the result of calling cheerio.load on the webpage response.
The query should use standard jQuery.
checkStatus takes the result from queryFunction and returns a boolean. When the result is true, a text
message will be triggered.
This library uses Twilio to send text messages. Once your account and number has
been established, fill out the information in config.js.
For more information on sending SMS from Node with Twilio, see their quickstart guide.
A sample monitor has been provided and can be found at monitors/google.js. This monitor checks Google's
home page. The provided queryFunction looks for the element with id="hplogo" and returns the alt
attribute of that element, which should be "Google". The configured checkStatus function checks that the
alt attribute does not equal "Google". If you want to see the texting behavior, change the checkStatus
to check that the attribute does equal "Google" and a text message will be sent to the configured number.
In order to build and test the Lambda locally, you will need to install the AWS SAM CLI
To build the Lambda, run the following:
sam build
To test the monitor locally, run the following
sam local invoke
To deploy the application, run the following:
sam build
sam deploy --guided