Very simple way how to get email alert when one of your linux servers/VMs/VPS is running out of space.

1. Install HTTP API in docker. This will receive information from your servers. And if some server has less than 10% free space it will send you email.

docker pull ghcr.io/urza/spacechecker:main && docker run -d -p 7373:8080 --restart=always --name SpaceCheckAPI -e EmailFrom='FROM@EMAIL' -e EmailTo='TO@EMAIL' -e SmtpUserName='SMTP_LOGIN' -e SmtpPwd='SMTP_PASSWORD' -e SmtpServer='SMTP_SERVER' ghcr.io/urza/spacechecker:main

Replace your SMTP info that the API will use to send emails.

Check it is running http://localhost:7373 - you should see a message with list of two valid endpoints: /last and /testmail

Then grab the URL where this is accesible and reachable from your servers. You may want to put this behind reverse proxy.

2. Install the cron script on your servers/VMs/VPS etc that you want to monitor. They will periodically post information about their disk ("/") usage to the api.

curl -sSL "https://raw.githubusercontent.com/urza/SpaceChecker/main/space_checker_install.sh" | sh -s "http(s)://API_ADDRESS"

Replace http(s)://API_ADDRESS with your API's real address.

If you want the server send info about other filesystem than just "/", modify the space_checker.sh script on that server after it is installed.

After a while you can check the API/last that it has some data. How often servers post data to api depends on the cron job. You may test sending emails by API/testmail.