Hi Peng Hui (and Garren),
I think the Prometheus support would be an awesome feature!
>From the e-mail it's not clear to me what would happen to the already
existing endpoints mentioned (`_stats`, `_system` and
`_active_tasks`).
Are they going to be deprecated / removed? Or does the info become
available in multiple formats (and places)?
Thank you,
Donat
On Tue, 22 Sep 2020 at 14:55, jiangph <jiangpeng...@hotmail.com> wrote:
>
> Hey all,
>
> We would like to add a Prometheus metrics endpoint for CouchDB and wanted to
> see if the community would be interested in us contributing this to CouchDB
> 4.x.
>
> Prometheus is a CNCF open-source project and the Prometheus metrics endpoint
> format is supported by many monitoring tools. Its data model is based around
> having a metric name which then contains a label name and a label value:
>
> <metric name>{<label name>=<label value>, ...}
>
> And it supports the Counter, Gauge, Histogram, and Summary metric types.
>
> The idea for the new Prometheus endpoint, /_metrics, would be that the
> endpoint is a consolidation of the _stats [1], _system [2], and
> _active_tasks [3] endpoints.
>
> For _stats and _system, the conversion from JSON to Prometheus-based format
> seems to be straightforward.
>
> JSON format:
> {
> "value": {
> "min": 0,
> "max": 0,
> "arithmetic_mean": 0,
> "geometric_mean": 0,
> "harmonic_mean": 0,
> "median": 0,
> "variance": 0,
> "standard_deviation": 0,
> ...
> "percentile": [
> [
> 50,
> 0
> ],
> [
> 75,
> 0
> ],
> [
> 90,
> 0
> ],
> [
> 95,
> 0
> ],
> [
> 99,
> 0
> ],
> [
> 999,
> 0
> ]
> ],
> "histogram": [
> [
> 0,
> 0
> ]
> ],
> }
>
> Prometheus-based format:
>
> couchdb_stats{value="min"} 0
> couchdb_stats{value="max"} 0
> couchdb_stats{value="percentile50"} 0
> couchdb_stats{value="percentile75"} 0
> couchdb_stats{value="percentile95"} 0
>
> For _active_tasks, the change will be a bit more complicated, and some fields
> will be added to labels and tags.
>
> JSON format:
>
> {
> "checkpointed_source_seq": 68585,
> "continuous": false,
> "doc_id": null,
> "doc_write_failures": 0,
> "docs_read": 4524,
> "docs_written": 4524,
> "missing_revisions_found": 4524,
> "pid": "<0.1538.5>",
> "progress": 44,
> "replication_id": "9bc1727d74d49d9e157e260bb8bbd1d5",
> "revisions_checked": 4524,
> "source": "mailbox",
> "source_seq": 154419,
> "started_on": 1376116644,
> "target": "http://mailsrv:5984/mailbox <http://mailsrv:5984/mailbox>",
> "type": "replication",
> "updated_on": 1376116651
> }
>
> Prometheus-based would look something like:
>
> format:couchdb_active_task{type="replication", source="mailbox",
> target="http://mailsrv:5984/mailbox <http://mailsrv:5984/mailbox>",
> docs_count = "docs_read"} 4524
> couchdb_active_task{type="replication", source="mailbox",
> target="http://mailsrv:5984/mailbox <http://mailsrv:5984/mailbox>",
> docs_count = "docs_written"} 4524
> couchdb_active_task{type="replication", source="mailbox",
> target="http://mailsrv:5984/mailbox <http://mailsrv:5984/mailbox>",
> docs_count = "missing_revisions_found"} 4524
>
>
> Best regards,
> Garren Smith
> Peng Hui Jiang
>
> [1]
> https://docs.couchdb.org/en/latest/api/server/common.html#node-node-name-stats
>
> <https://docs.couchdb.org/en/latest/api/server/common.html#node-node-name-stats>
> [2] https://docs.couchdb.org/en/latest/api/server/common.html#active-tasks
> <https://docs.couchdb.org/en/latest/api/server/common.html#active-tasks>
> [3]
> https://docs.couchdb.org/en/latest/api/server/common.html#node-node-name-system
>
> <https://docs.couchdb.org/en/latest/api/server/common.html#node-node-name-system>
