fb85b27ae3
The prometheus datasource was reporting host_ram_usage in MiB as described in the docstring for the base datasource interface definition [1]. However, the gnocchi datasource is reporting it in KiB following ceilometer metric `hardware.memory.used` [2] and the strategies using that metric expect it to be in KiB so the best approach is to change the unit in the prometheus datasource and update the docstring to avoid missunderstandings in future. So, this patch is fixing the prometheus datasource to return host_ram_usage in KiB instead of MiB. Additionally, it is adding more unit tests for the check_threshold method so that it covers the memory based strategy execution, validates the calculated standard deviation and adds the cases where it is below the threshold. [1]15981117ee/watcher/decision_engine/datasources/base.py (L177-L183)[2] https://docs.openstack.org/ceilometer/train/admin/telemetry-measurements.html#snmp-based-meters Closes-Bug: #2113776 Change-Id: Idc060d1e709c0265c64ada16062c3a206c6b04fa (cherry picked from commit6ea362da0b)