Add following metrics:
- used_inodes
- total_inodes
- healing
- online
- reads_per_sec
- reads_kb_per_sec
- reads_await
- writes_per_sec
- writes_kb_per_sec
- writes_await
- perc_util
To be able to calculate the `per_sec` values, we capture the IOStats-related
data in the beginning (along with the time at which they were captured),
and compare them against the current values subsequently. This is because
dividing by "time since server uptime." doesn't work in k8s environments.
Metrics v3 is mainly a reorganization of metrics into smaller groups of
metrics and the removal of internal aggregation of metrics received from
peer nodes in a MinIO cluster.
This change adds the endpoint `/minio/metrics/v3` as the top-level metrics
endpoint and under this, various sub-endpoints are implemented. These
are currently documented in `docs/metrics/v3.md`
The handler will serve metrics at any path
`/minio/metrics/v3/PATH`, as follows:
when PATH is a sub-endpoint listed above => serves the group of
metrics under that path; or when PATH is a (non-empty) parent
directory of the sub-endpoints listed above => serves metrics
from each child sub-endpoint of PATH. otherwise, returns a no
resource found error
All available metrics are listed in the `docs/metrics/v3.md`. More will
be added subsequently.
