Custom Checks Support (e.g. bash scripts, local health endpoints)

Hello Checkmate team,

First of all, thanks a lot for your work on Checkmate — it’s a very handy and elegant tool to monitor containers and services in self-hosted environments.

I’m currently using Checkmate to monitor my CapRover server, and it works great. However, I’d love to have the ability to add custom checks, for example:

- Execute a simple bash script and evaluate its exit code or output (e.g. a backup verification script)
- Monitor a local JSON file or REST endpoint (e.g. /var/www/restic-status.json) and parse the status
- Use the check result to trigger a “FAIL” or “PASS” status in Checkmate UI

This would allow users to:

- Monitor backup success (e.g. Restic, Duplicati, rsync)
- Integrate external services that don’t expose standard ports or endpoints
- Trigger alerts based on internal cron scripts or service health indicators

Would it be possible to support:

- A custom check type?
- Or at least a way to fetch and parse a local or HTTP-exposed JSON file?

I’d be happy to help test this or provide example use cases/scripts if needed.

Thanks again for your time and consideration!

Best,
Damien

No files, tests, or entry points are identified in the issue. Start by locating the existing check types and status evaluation flow, then define the supported custom-check inputs, execution or fetching behavior, parsing rules, and PASS/FAIL completion criteria.

Written by the indexing model from the issue text.