Hey Donat,
Thanks for checking. The idea is to keep the _stats, _system and _active_tasks
endpoints to be backward compatible. If Prometheus endpoint is used widely, we
can consider to deprecate these endpoints.
Best regards,
Peng Hui
> On Sep 23, 2020, at 1:05 AM, Bessenyei Balázs Donát <bes...@apache.org> wrote:
>
> 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>
