# nasmon

Lightweight NAS health monitor: web dashboard on port 8090 with CPU, memory
(incl. ZFS ARC), temperatures, physical disks with SMART, ZFS pools and datasets;
periodic SMART/ZFS checks with e-mail alerts.

* Web UI:      http://<host>:8090
* Settings:    http://<host>:8090/settings  (also /etc/nasmon/config.json)
* State:       /var/lib/nasmon/nasmon.db  (SMART history, alert log)
* Service:     systemctl status nasmon ; journalctl -u nasmon -f
* JSON API:    /api/status, /api/history?hours=24, /api/disks/<serial>/history?days=30

## ZFS datasets from the UI

The ZFS page (http://<host>:8090/zfs) can create datasets in a pool — name (nested
names like media/video are fine), owner uid:gid for the mountpoint, compression,
optional quota — and destroy datasets that are empty (no data, no children, no
snapshots; the check is repeated against the live system before "zfs destroy").

nasmon runs sandboxed (ProtectSystem=strict → own mount namespace), so these
commands are executed on the host through transient units:
`systemd-run --wait --pipe --collect zfs create …`. Every action is logged
(journalctl -u nasmon).

nasmon has no authentication: keep port 8090 on the LAN only.

## SMB / NFS shares from the UI

http://<host>:8090/shares manages Samba shares (guest or per-user, files always
written as the data owner uid 1000), SMB users (smbpasswd; a login-less Unix
account is created when needed) and NFS exports (host/IP/CIDR clients, rw/ro,
squash). A share can point to any existing folder (ZFS dataset, USB disk under
/mnt or /media, /srv…) except system directories (/etc, /usr, /var, /boot…),
also after resolving symlinks. Definitions are stored in
/etc/nasmon/shares.json; nasmon regenerates
/etc/samba/smb.conf (whole file, header "Managed by nasmon") and
/etc/exports.d/nasmon.exports, validates with testparm, then reloads smbd /
exportfs -ra. A rejected config is rolled back to the .bak copy. Daemons are
enabled while at least one share exists and disabled otherwise.

Alerts: the × on an open alert acknowledges it (hidden and not mailed until the
problem changes or clears); the × on a resolved alert removes it from the log.
Resolved alerts older than 7 days are hidden by default, older than 90 days
deleted.