Is there any metrics counting the invocation of object storage service API?

[leiysky]

I'd like to know the count of PUT/GET operations happen in a certain time range.

[koushiro]

OpenDAL provides several metrics layer implementations (PrometheusLayer, PrometheusClientLayer and MetricsLayer).
They all provide the same metrics. Are these enough for you?

[tisonkun]

I check all those layers but don't find a metric indicator for this certain purpose. If there is one, could you name it out?

[koushiro]

opeartion_duration_seconds histogram metric with operation label, like below:

operation_duration_seconds_count{scheme="fs",namespace="",root="/private/tmp",operation="write"} 1

[tisonkun]

Thank you! What does "duration_seconds" mean? Or how can I interpret this metrics with value n?

I think we may need to document the metrics we report in some way ..

[koushiro]

This should be the semantics of histogram metric type, so I think it's enough to just describe this histogram metric (operation_duration_seconds) itself.

metrics doc: https://docs.rs/opendal/latest/opendal/layers/observe/index.html#prometheus-metrics

[tisonkun]

Thank you @koushiro! I understand the metrics now. And I found that the mertics isn't quite aligned so I wonder which metric is precious. It seems depend on the code but I'd like to know if a Writer::write always indicates a write, and whether I can map the metrics directly to (e.g., S3's) PUT/GET requests.

[tisonkun]

I observe some example metrics:

write 714338
Writer::write 714338
Writer::close 714340

Reader::read 3644821319
read 1085649

.. and I'm not quite sure what is the real PUT/GET metrics.

[koushiro]

Yes, this is confusing for users.

According to the current implementation of the metrics layer, it only records the data of the specific operation being called, like below:

write => Operation for [`crate::raw::Access::write`]
Writer::write => Operation for [`crate::raw::oio::Write::write`]

read => Operation for [`crate::raw::Access::read`]
Reader::read => Operation for [`crate::raw::oio::Read::read`]

so I think write/read may be the expected PUT/GET data for you.

[tisonkun]

Cool!