feat: add parameter to allow return expired cache in case of errors

[fgouteroux]

Hi @ricoberger,

I would like to add this feature with the parameter useExpiredCacheOnError, in some case it help when we have a script execution doing some flip/flap caused by a timeout.

With theses parameters:

useExpiredCacheOnError: true
cacheDuration: 5m

It produces the following metrics:

# TYPE script_use_cache gauge
script_use_cache{script="get_objecstorage_tenant_usage"} 1
# HELP script_use_expired_cache Script re-use expired cache (0 = no, 1 = yes).
# TYPE script_use_expired_cache gauge
script_use_expired_cache{script="get_objecstorage_tenant_usage"} 1

I added the metric script_use_cache as it could be interesting to know if metrics are coming from cache or not.

Let me know what do you think about that.

[ricoberger]

Hi @fgouteroux thanks for your contribution 🙂