Bad use of labels about prometheus-lvm-exporter HOT 2 OPEN

Thank you for your feedback and observation. You're right, stuffing all non-numeric fields into *_info was probably a bad choice in hindsight. The code has been out there for almost two years and such fundamental changes need to be gradual. Start by emitting the new metrics and add a flag to disable the old ones and after some amount of time delete the old labels.

We can add *_info-esque metrics for the non-numeric values:

lvm_lv_info{lv_name="lv_db_backup",lv_uuid="r7Btja-…"} 1
lvm_lv_attr{lv_uuid="r7Btja-…",value="-wi-ao----"} 1

I'd keep a few basic things like the name in _info. What do you think?

Also, UUID as only label on the other metrics makes data querying very complex.

The UUID is the only stable identifier during the lifetime of an object in LVM. Examples from my own rules:

lvm_pv_info{pv_attr=~"..[^-].*"} or on (instance, pv_uuid)
lvm_pv_missing > 0

lvm_vg_info{vg_attr=~"...[^-].*"} or on (instance, vg_uuid)
lvm_vg_missing_pv_count != 0 or on (instance, vg_uuid)
lvm_vg_partial != 0

from prometheus-lvm-exporter.

I understand the non-breaking decision.

My point was not to split metrics into even more label-only metrics. Ideally I wish they were gone, but I understand that for the sake of non breaking things they won't. Having metrics which are always equal to 1 and whose labels play the role of metrics dosn't make any sense to me, as this is poisoning how prometheus manages and stores its metrics. You have even lv_active which has a numeric value (0 or 1) as a label while it should clearly be the value of a dedicated metric, say lvm_lv_active.

Every labels that has a finite number of values (for example lv_permissions) should have its own dedicated metric, and the values matched to integers.

IMHO the only labels to be kept as is are the properties that defines the entity (for example lv_dm_path, lv_uuid, lv_name which are by nature stable and normally won't change (I know you can technically change a lv name, but that's not something that is volatile by nature). Those labels should also be added to all metrics, not only the *_info ones

Optionally, have a setting to let the user add any label needed.

from prometheus-lvm-exporter.