Website Monitor

This project monitors a specific URL to match a predefined regular expression. In case of a match it will send an email to the configured email address.

The services makes use of the AWS Lamda stack to schedule the app every two minutes.

Serverless with AWS Node

This is an example of creating a function that runs as a cron job using the serverless schedule event. For more information on schedule event check out the Serverless docs on schedule.

Schedule events use the rate or cron syntax.

Rate syntax

rate(value unit)

value - A positive number

unit - The unit of time. ( minute | minutes | hour | hours | day | days )

Example rate(5 minutes)

For more information on the rate syntax see the AWS docs

Cron syntax

cron(Minutes Hours Day-of-month Month Day-of-week Year)

All fields are required and time zone is UTC only.

Field	Values	Wildcards
Minutes	0-59	, - * /
Hours	0-23	, - * /
Day-of-month	1-31	, - * ? / L W
Month	1-12 or JAN-DEC	, - * /
Day-of-week	1-7 or SUN-SAT	, - * ? / L #
Year	192199	, - * /

Read the AWS cron expression syntax docs for more info on how to setup cron

Test

REGEX='REGEX' URL='https://example.com' SENDGRID='APIKEY' EMAIL='[email protected]' node --inspect-brk test.js

Deploy

In order to deploy the endpoint you simply run

serverless deploy

Result is something like this:

Serverless: Packaging service...
Serverless: Uploading CloudFormation file to S3...
Serverless: Uploading service .zip file to S3 (1.47 KB)...
Serverless: Updating Stack...
Serverless: Checking Stack update progress...
..............
Serverless: Stack update finished...
Service Information
service: check-website-for-string
stage: dev
region: us-east-1
stack: check-website-for-string-dev
resources: 7
api keys:
  None
endpoints:
  None
functions:
  cron: check-website-for-string-dev-cron
layers:
  None

Configure Environment

Regex An email will be sent out if the provided regular expression is machted. If you want to negate a regular expression, you can do it like this ^((?!not available).)*$.

Logs

AWS CloudWatch Logs

• Open the Logs page of the CloudWatch console.

Serverless CLI

To see your cron job running tail your logs with:

serverless logs --function cron --tail