compact: --web.external-prefix does not work

[sepich]

Thanos, Prometheus and Golang version used:
master-2020-03-27-4e5c2f25

Object Storage Provider:
GCP

What happened:
I'm trying to get new web UI of thanos-compact behind reverse proxy under path /bucket.
Starting container wit such arguments:

          args:
          - compact
          - --wait
          - --web.external-prefix=/bucket

But then thanos-compact:10902/bucket returns 404.
/ returns html with all css/js sources leading to /static

What you expected to happen:
I expect at least html would have links to /bucket/static.
Would be much better to also have --web.route-prefix option for compact too.

How to reproduce it (as minimally and precisely as possible):

$ kubectl port-forward thanos-compact-7fc65f9df5-sjqnt 10902 &
$ curl -s localhost:10902 | grep static
Handling connection for 10902
        <link rel="shortcut icon" href="/static/img/favicon.ico?v=4e5c2f251b5b73e804883d9b42cd9246d32328db">
        <script src="/static/vendor/js/jquery-3.3.1.min.js?v=4e5c2f251b5b73e804883d9b42cd9246d32328db"></script>
        <script src="/static/vendor/js/popper.min.js?v=4e5c2f251b5b73e804883d9b42cd9246d32328db"></script>
        <script src="/static/vendor/bootstrap-4.1.3/js/bootstrap.min.js?v=4e5c2f251b5b73e804883d9b42cd9246d32328db"></script>
        <link type="text/css" rel="stylesheet" href="/static/vendor/bootstrap-4.1.3/css/bootstrap.min.css?v=4e5c2f251b5b73e804883d9b42cd9246d32328db">
        <link type="text/css" rel="stylesheet" href="/static/css/prometheus.css?v=4e5c2f251b5b73e804883d9b42cd9246d32328db">
        <link type="text/css" rel="stylesheet" href="/static/vendor/bootstrap4-glyphicons/css/bootstrap-glyphicons.min.css?v=4e5c2f251b5b73e804883d9b42cd9246d32328db">
    <script type="text/javascript" src="https://www.gstatic.com/charts/loader.js"></script>
    <script src="/static/js/bucket.js?v=4e5c2f251b5b73e804883d9b42cd9246d32328db"></script>
    <script src="/static/vendor/moment/moment.min.js?v=4e5c2f251b5b73e804883d9b42cd9246d32328db"></script>

Full logs to relevant components:

Logs

$ k logs -f thanos-compact-7fc65f9df5-sjqnt
level=info ts=2020-03-29T20:57:09.519805115Z caller=main.go:152 msg="Tracing will be disabled"
level=info ts=2020-03-29T20:57:09.520003815Z caller=factory.go:46 msg="loading bucket configuration"
level=info ts=2020-03-29T20:57:09.522286298Z caller=compact.go:321 msg="deduplication.replica-label specified, vertical compaction is enabled" dedupReplicaLabels=replica
level=info ts=2020-03-29T20:57:09.522809961Z caller=compact.go:474 msg="starting compact node"
level=info ts=2020-03-29T20:57:09.522848156Z caller=intrumentation.go:48 msg="changing probe status" status=ready
level=info ts=2020-03-29T20:57:09.523069571Z caller=bucket.go:487 msg="synchronizing block metadata"
level=info ts=2020-03-29T20:57:09.523741091Z caller=intrumentation.go:60 msg="changing probe status" status=healthy
level=info ts=2020-03-29T20:57:09.523775995Z caller=http.go:56 service=http/server component=compact msg="listening for requests and metrics" address=0.0.0.0:10902
level=info ts=2020-03-29T20:57:12.75033743Z caller=compact.go:870 msg="start sync of metas"
level=info ts=2020-03-29T20:57:15.09858552Z caller=bucket.go:500 msg="downloaded blocks meta.json" num=69
level=info ts=2020-03-29T20:57:15.244699051Z caller=compact.go:876 msg="start of GC"
level=info ts=2020-03-29T20:57:15.244862744Z caller=compact.go:884 msg="start of compaction"
level=info ts=2020-03-29T21:02:09.525270249Z caller=bucket.go:487 msg="synchronizing block metadata"
level=info ts=2020-03-29T21:02:12.257899714Z caller=bucket.go:500 msg="downloaded blocks meta.json" num=69
level=info ts=2020-03-29T21:07:28.444590494Z caller=bucket.go:487 msg="synchronizing block metadata"
level=info ts=2020-03-29T21:08:25.264457965Z caller=bucket.go:500 msg="downloaded blocks meta.json" num=69
level=info ts=2020-03-29T21:12:09.523158194Z caller=bucket.go:487 msg="synchronizing block metadata"
level=info ts=2020-03-29T21:12:12.334746629Z caller=bucket.go:500 msg="downloaded blocks meta.json" num=69
level=info ts=2020-03-29T21:17:09.540147617Z caller=bucket.go:487 msg="synchronizing block metadata"
level=info ts=2020-03-29T21:17:12.286737077Z caller=bucket.go:500 msg="downloaded blocks meta.json" num=71
level=info ts=2020-03-29T21:22:09.523203447Z caller=bucket.go:487 msg="synchronizing block metadata"
level=info ts=2020-03-29T21:22:12.238231324Z caller=bucket.go:500 msg="downloaded blocks meta.json" num=71
level=warn ts=2020-03-29T21:24:29.661382461Z caller=ui.go:42 msg="Could not get file info" err="AssetInfo pkg/ui/static/vendor/bootstrap-4.1.3/js/bootstrap.min.js.map not found" file=pkg/ui/static/vendor/bootstrap-4.1.3/js/bootstrap.min.js.map
level=warn ts=2020-03-29T21:24:29.661855792Z caller=ui.go:42 msg="Could not get file info" err="AssetInfo pkg/ui/static/vendor/bootstrap-4.1.3/css/bootstrap.min.css.map not found" file=pkg/ui/static/vendor/bootstrap-4.1.3/css/bootstrap.min.css.map
level=warn ts=2020-03-29T21:24:29.724234105Z caller=ui.go:42 msg="Could not get file info" err="AssetInfo pkg/ui/static/vendor/js/popper.min.js.map not found" file=pkg/ui/static/vendor/js/popper.min.js.map

[bwplotka]

Something to be added/fixed indeed.

I fixed some bug around this here: #2357 do you mind trying current master?

[squat]

hi, I just tested against current master with --web.external-prefix=/bucket and it is working correctly:

I think we can probably safely close this issue

[sepich]

Confirming /bucket/global works fine in this configuration for v0.12.0

[jdfalk]

I think this was closed prematurely.
--web.external-prefix= is supposed to be for the external path as referred to in links but is supposed to serve the content still from /
--web.route-prefix= is supposed to actually serve it on a subpath, unfortunately compact currently lacks this flag.

 --web.route-prefix=""      Prefix for API and UI endpoints. This allows thanos UI to be served on a sub-path. This option is analogous to --web.route-prefix of Promethus.
 --web.external-prefix=""   Static prefix for all HTML links and redirect URLs in the UI query web interface. Actual endpoints are still served on / or the web.route-prefix. This allows thanos UI to be served behind a reverse proxy that strips a URL sub-path.

If connecting to localhost it should be http://localhost:10902/loaded but on the reverse proxy it would be http://external/prefix/loaded which would get rewritten as http://internal/loaded