Thanks, Joan for your reply around your vacation. Good suggestion about the proposed job config for prometheus endpoint.
I will come up with more details after integrating these valuable suggestions. Thanks, Peng Hui > On Sep 24, 2020, at 4:35 AM, Joan Touzet <woh...@apache.org> wrote: > > Looking at the Prometheus scrape documentation, you can specify a full URL. > > https://prometheus.io/docs/prometheus/latest/configuration/configuration/#scrape_config > > Jan's suggestion of using /_{info|metrics}?accept=prometheus with the default > being JSON would be better for CouchDB than the default output being > Prometheus, and is a minor change. > > So the job config would look like: > > - job_name: 'couchdb' > targets: my-couchdb-host.domain.com:5984 > metrics_path: /_{info}metrics} > params: > accept: prometheus > > I would be OK with a first pass only providing this format but I would > strongly prefer the JSON version come ASAP, and be the default for the > endpoint if no query parameter is passed - unless Prometheus provides > something we can use as a unique identifier in the request headers. (If it > does you can use that to eliminate the params: line.) > > As I'm on holiday for another 10 days that's about the most I want to think > about this right now. Jan has covered my other concerns and discussion should > happen in his thread. > > -Joan > > On 23/09/2020 05:17, jiangph wrote: >> Thanks Joan for your quick response and suggestion. As we can see, JSON is >> not the standard Prometheus format for _metrics endpoint. In order to be >> compatible with many monitoring tools, what about going with Prometheus >> standard format first and we may add JSON format support later? >> Best regards, >> Peng Hui >>> On Sep 23, 2020, at 9:41 AM, Joan Touzet <woh...@apache.org> wrote: >>> >>> I like this, but not at the expense of JSON output. It would be the only >>> new API surface for CouchDB that isn't JSON-based, and there needs to be >>> excellent justification for such. Prometheus is well-known enough to be >>> supported, but we should continue to put out JSON stats for the foreseeable >>> future. >>> >>> I know that Prometheus can't send a header, but sending an accepts >>> application/json to /_metrics and having it send back the same data as >>> Prometheus, but in JSON, would be lovely. If you feel up to it :) >>> >>> -Joan "on vacation" Touzet >>> >>> On 2020-09-22 8:55 a.m., jiangph 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> <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> >>>> <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> >>>> <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> >>>> <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> >>>> >>>> <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> >>>> <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> >>>> >>>> <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>>
