add unit test for v3 metrics for all its exposed endpoints
Bonus:
- support OpenMetrics encoding
- adds boot time for prometheus
- continueOnError is better to serve as
much metrics as possible.
This would reduce the size of data in response of metrics
listing. While graphing we can default these metrics with
a zero value if not found.
Signed-off-by: Shubhendu Ram Tripathi <shubhendu@minio.io>
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.
