Micrometer route gets sub router attached at the end

[basalt79]

Version

vertx: 4.5.7 - 4.5.11

Context

Define a main route and add a sub route.
Calling sub route api.
on 200 -> route string in metrics looks ok
on fail() -> route string in metrics gets the sub route attached at the end of the url.

Reproducer

see: https://github.com/basalt79/vertx-web-metrics

Steps to reproduce

1. Launch MainVerticleTest
2. see failing tests

OR

1. Launch MainVerticle
2. navigate to

http://localhost:7777/good
http://localhost:7777/bad
http://localhost:7777/notfound
http://localhost:7777/first/good
http://localhost:7777/first/bad
http://localhost:7777/first/notfound
http://localhost:7777/first/second/good
http://localhost:7777/first/second/bad
http://localhost:7777/first/second/notfound

and check afterwards the metrics result at http://localhost:7777/metrics

Extra

Since the effect of this hits metrics, i put this issue here, but maybe the root cause is located at https://github.com/vert-x3/vertx-web/

[tsegismont]

Thanks for your report @basalt79

Does the issue affect 4.5.6 as well?

[basalt79]

Thanks for taking care @tsegismont .
Yes, with 4.5.6, 4.5.5, 4.5.3 its the same behavior. I created a branch for this version, see https://github.com/basalt79/vertx-web-metrics/tree/4.5.6

[basalt79]

I have added a reproducer with 4.0.0, this was the first version where the route was added to the metrics.
https://github.com/basalt79/vertx-web-metrics/tree/4.0.0

this happens only if I use subRouter like https://github.com/basalt79/vertx-web-metrics/blob/4.0.0/src/main/java/com/noenv/georg/MainVerticle.java#L104

@tsegismont
If I define each route dedicated, its working https://github.com/basalt79/vertx-web-metrics/blob/4.0.0/src/main/java/com/noenv/georg/MainVerticle.java#L81

i have not adapted the unit tests, because if i dont use subRouter, the />/ part is missing anyway.

since we use subRouter for the main API routes from Swagger, the behavior is on every service.

[tsegismont]

Thank you for all these details, I'll look into your reproducer

[basalt79]

Hi @tsegismont , have you already got the chance to take a look at the reproducer?

[tsegismont]

@basalt79 I was able to write a unit test for vertx-micrometer-metrics thanks to your reproduce. I'll share my findings when I understand the cause.

In case you haven't figured it out yourself, you could write a MeterFilter to change the bad metrics name

[tsegismont]

When the route label is enabled, the Vert.x Web Router can notify the metrics SPI implementation that a route handler has been invoked.

For example, if you set two routes with same path:

router.route("/bad").handler(RoutingContext::next);
router.route("/bad").handler(ctx -> ctx.fail(500));

You will get a metric with route tag that contains:

/bad>/bad

Similarly, if you invoke reroute:

router.route("/good").handler(ctx -> ctx.reroute("/first/second/bad"));

The metric route tag contains:

/first/>/second/>/good>/first/>/second/>/bad

Back to your reproducer, when ctx.fail is invoked, the router is traversed again from the root level to find a failure handler. If the request uri starts with /first/second, the subrouter bound to /first and /second are traversed, in this order, this is why the metric route tag contains /bad>/first/>/second/.

So this works as designed. Have you tried to create a MeterFilter to modify the route tag that are not suitable or perhaps you could disable the route label, and use matchers with the path label?

[basalt79]

Hi @tsegismont I will check the MeterFilter and also have a look at the Matchers thx for the hit!
currently we work around with wildcards in Prometheus queries.

[tsegismont]

Thanks for your feedback!