Website change monitor action

Sometimes you need to monitor a website, or a particular part of it, for changes in its content. There are some services that provide this functionality, but usually require a paid subscription to monitor at an acceptable frequency.

This Action provides this functionality for free by leveraging the GitHub infrastructure. The only limit is that checks can occur at a minimum of 5 minutes intervals, as per the limits of GitHub Actions. For now, it supports notifications via Discord and Slack webhooks.

Usage

1. Create a new repository or choose an existing one.

2. Create a personal access token with access to the chosen repository and read and write access to Variables.

   Copy the token to the clipboard.

3. Navigate to the chosen repository and go to the Settings tab.

   Click on Secrets and Variables, Actions and then New repository secret.

   In the Name field, type GH_TOKEN and in the Secret field, paste the token copied in step 2.

4. Create a new workflow file in the .github/workflows directory of the repository with a .yaml extension and the following content adjusted to your needs:

on:
    schedule:
        - cron: "*/5 * * * *" # every 5 minutes (minimum interval), replace with desired cron expression
jobs:
    monitoring_job:
        runs-on: ubuntu-latest
        name: "Monitoring job"
        steps:
            - name: Checkout
              uses: actions/checkout@v4
            - name: "Check for updates"
              uses: lcian/website-change-monitor-action@v1
              id: check
              with:
                  url: "https://example.com" # replace with desired URL
                  selector: "#content-core" # (optional) replace with CSS selector of element you want to monitor, omit this to monitor the whole page or if the page is not HTML
                  discord-webhook-url: "https://discord.com/api/webhooks/..." # (optional) replace with Discord webhook URL if you want to get Discord notifications
                  slack-webhook-url: "https://hooks.slack.com/services/..." # (optional) replace with Slack webhook URL if you want to get Slack notifications
              env:
                  GH_TOKEN: ${{ secrets.GH_TOKEN }}

5. Commit the changes and push them to the repository.

   You should see the workflow running on your desired schedule in the Actions tab of the repository.

   If you want to disable the checker, just delete the file you created at step 5.

How it works

The code for this Action is very simple, it uses axios to send HTTP requests and cheerio to extract the contents of the HTML element corresponding to a particular CSS selector.

The data is hashed and stored in a repository Variable. Whenever the current hash is different from the previous one, it means that the content has changed, so we fire alerts to the provided webhook URLs.

Contributing

Feel free to open an issue or a pull request.