is-my-site-up

This pings a URL and emails you if it doesn't return 200. It is packaged into a Terraform module that creates a Google Cloud Function that by default runs every day. The resources created by the module, run at the default once a day frequency, are within the Google free tier.

Setup

Requirements

• A Gmail account to send the email. I strongly recommend that you create a dedicated account for this, as configuring a Gmail account to be accessible to this script involves disabling security features, such as turning on less secure apps access.
• Google Cloud Platform account
• Terraform

Configure the Gmail account

• Create a Gmail account
• Go to the less secure apps section of settings
• Turn allow less secure access on
• (Optional) Change the account inactivity settings to the maximum of 18 months and configure the inactivity warnings, so if your site is very stable, your monitoring won't silently disappear

Run the Terraform

• You will need the Cloud Functions, Cloud Scheduler and Cloud Build APIs enabled to run the terraform. Terraform prompts you to enable them so personally I keep applying and clicking through on the enable links until it works
• You will need to create an App Engine instance (don't run any actual code on it if you want to stay in the Google free tier)

Invoke the module in your terraform, e.g.

module "cheatsheet" {
  source = "./terraform"

  gmail_account  = "[email protected]"
  urls_to_check  = "https://terraform-cheatsheet.uk"
  email_to_alert = "[email protected]"
}

Run terraform plan and terraform apply to create the Cloud Function.

You will then need to manually create the Gmail password secret in Cloud Secrets and add it to the Cloud function by following this documentation (add it as an environment variable called GMAIL_PASSWORD). It's not currently possible to configure that in the terraform cloud function definition but it hopefully will be soon.