Website --web.enable-admin-api confusion

[ericdstein]

Thanos, Prometheus and Golang version used:
Thanos: v0.15
Prometheus: 2.21

In multiple places, including the sidecar docs, I have seen the following statement.

The --web.enable-admin-api flag is enabled to support sidecar to get metadata from Prometheus like external labels.

It doesn't appear, however, that this flag controls access to metadata. Instead, it appears to control access to perform certain admin tasks and thus may only be required if using the Sidecar to send data to object storage. If one were to just use Query, is this flag required to be set for Prometheus?

[yeya24]

Right, it is confusing and I believe this flag is not needed. Prometheus external labels are fetched from /api/v1/status/config directly.

[bwplotka]

Not really, we use flags endpoint as well.

[bwplotka]

But overall, let's double check we added this piece of doc and requirement at the very start of Thanos, I suppose for snapshot purposes, although we don't use it now on sidecar. So there is some chances that this flag is not needed at all. (:

[ericdstein]

Thank you both! :-) I found the reason the statement was added. Prior to #1354 #1355, the ExternalLabels func incorrectly returned error is 'web.enable-admin-api' flag enabled? got non-200 response code. The recommendation was added when someone encountered this error.

The only func I could find that calls an admin api is the Snapshot func in promclient. But, as was stated, I couldn't find where that func is currently used.

[yeya24]

@ericdstein Thanks for checking. I think this snapshot is outdated and not used anymore. It is safe to remove that.

[stale]

Hello 👋 Looks like there was no activity on this issue for the last two months.
Do you mind updating us on the status? Is this still reproducible or needed? If yes, just comment on this PR or push a commit. Thanks! 🤗
If there will be no activity in the next two weeks, this issue will be closed (we can always reopen an issue if we need!). Alternatively, use remind command if you wish to be reminded at some point in future.

[stale]

Closing for now as promised, let us know if you need this to be reopened! 🤗

[id-tari]

Latest documents still describe enabling of --web.enable-admin-api as a recommendation.
https://thanos.io/v0.30/components/sidecar.md/