Health checks
Free HTTP, HTTPS, certificate and TCP checks of an instance's public addresses, with an email when the application stops answering or a certificate is about to expire.
Health checks watch the application on your instance. Every minute hostd requests a URL or opens a TCP port on the instance's public address and emails the project owner when the result changes. The feature is free and in beta.
The checks run from inside the hostd network, so they tell you whether the application answers, not whether it is reachable from the internet. The state of the hostd network is on status.hostd.cloud.
Check types
- HTTP and HTTPS – a
GETrequest to the URL has to return the status code you set (200 by default). Redirects are not followed, so a page that redirects answers with 301 or 302. An HTTPS check does not validate the certificate, so it also works with a self-signed one. - Certificate – the certificate the instance serves for the host name is valid. You get an email 14, 7 and 1 day before it expires.
- TCP – the port accepts a connection.
Every check connects to the instance's address. The host name is sent as the TLS server name and the Host header, so a site behind a CDN is checked directly.
Add a check
- Open Monitoring → Health checks.
- Use Add next to the instance.
- Choose the type, the address if the instance has several, and enter the URL with the expected status code, the host name or the port.
The list shows the checks of the whole project, grouped by instance. You can filter it by check type and by instance.
An instance can have up to 5 checks. The check's menu has Edit, Pause (switches the check off without deleting it; Resume switches it back on) and Delete. After an edit the check starts over and its state is determined again.
States
- Up / Down – the state changes after two identical results in a row, so a restart shorter than a minute is not reported.
- Paused – you paused the check, or the instance is not running. Nothing is checked and no email is sent.
The bar shows the last 24 hours.
Emails
The project owner gets one email per project with everything that changed:
- a check went down or works again,
- a certificate expires in 14, 7 or 1 day,
- once a day, a reminder while something stays down (for 7 days).
When one check changes state more than 4 times in an hour, the further changes wait for the next email.
Firewall
The checks come from 155.133.32.17 and 2a0e:7d80::ff. If the instance firewall is on, allow these addresses for the checked ports. A check deleted together with its instance or public address needs no cleanup.