Disk Usage Check Fails to Monitor Host Filesystem in Docker Containers

[kilemensi]

Description

The current DiskUsage health check backend hardcodes the monitored path as /. This works fine when running natively. However, within a Docker container, it checks the container's root filesystem, and not the host's.

This makes the health check less useful in containerized environments, as it doesn't reflect the actual disk usage of the underlying host.

Suggestion

To enable monitoring the host's disk usage from within a container, a possible approach is to:

1. Allow configuration of the disk usage path via a setting (e.g., HEALTH_CHECK['DISK_USAGE_PATH']).
2. If HEALTH_CHECK['DISK_USAGE_PATH'] is set, use that path for psutil.disk_usage(). Otherwise, default to / for backward compatibility and non-containerized environments.

This would allow users to mount the host's filesystem to a specific path within the container (e.g., /host/) and then configure HEALTH_CHECK['DISK_USAGE_PATH'] to /host/ to monitor the correct disk usage.

This is the approach used by other monitoring solutions such as Prometheus' node_exporter

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Happy to send a PR if you agree with the approach.