Host agent was including Docker overlay2 mounts from TrueNAS SCALE's
.ix-apps directory in disk totals. These mounts inherit the ZFS pool's
AVAIL space, causing massively inflated storage numbers (e.g., 173 TB
per container overlay instead of actual usage).
Changes:
- Add /mnt/.ix-apps/docker/ to container overlay path exclusions
- Use ShouldSkipFilesystem() in host agent disk collection (was only
using ShouldIgnoreReadOnlyFilesystem() which missed container paths)
- Add test cases for TrueNAS overlay paths
Related to #718
- Refactor collector to support mocking
- Fix ZFS detection to support 'fuse.zfs' and case-insensitivity
- Add regression tests for ZFS dataset deduplication
Squashfs snap mounts on Ubuntu (and similar read-only filesystems like
erofs on Home Assistant OS) always report near-full usage and trigger
false disk alerts. The filter logic existed in Proxmox monitoring but
wasn't applied to host agents.
Changes:
- Extract read-only filesystem filter to shared pkg/fsfilters package
- Apply filter in hostmetrics.collectDisks() for host/docker agents
- Apply filter in monitor.ApplyHostReport() for backward compatibility
- Convert internal/monitoring/fs_filters.go to wrapper functions
This prevents squashfs, erofs, iso9660, cdfs, udf, cramfs, romfs, and
saturated overlay filesystems from generating alerts. Filtering happens
at both collection time (agents) and ingestion time (server) to ensure
older agents don't cause false alerts until they're updated.
