Fix unintuitive behaviour of RegisterAt with custom registry #181
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This commit fixes some counterintuitive behaviour when creating the middleware
with a custom registry.
Previously, using a custom registry with additional metrics requires avoiding
the RegisterAt function, which used only the prometheus.DefaultGatherer.
Given a *prometheus.Registry, instead of the more intuitive:
```
fp := fiberprometheus.NewWithRegistry(reg, "my-application", "http", "", nil)
fp.RegisterAt(app, "/metrics")
```
One would have to do this:
```
app.Get("/metrics", adaptor.HTTPHandler(promhttp.HandlerFor(reg, promhttp.HandlerOpts{})))
```
The change here detects when the `prometheus.Registerer` is also a
`prometheus.Gatherer`, and then uses the `prometheus.Gatherer` when calling
`RegisterAt`.
This change will _not_ fix work in the case of a custom implementation of
`prometheus.Registerer` when the that implementation is not _also_ a
`prometheus.Gatherer`, which is an unlikely situation for inexperienced users of
prometheus.
For the more common case of passing a `*prometheus.Registry`, this change will
provide a more intuitive experience.
|
Hi @ansrivas if this PR is not satisfactory, I'd be happy to attempt another solution. Am I wrong about expecting the API to work with the custom registry when using the |
|
Hello @calloway-jacob, sorry for taking time in reviewing this, a bit busy lately. |
ansrivas
approved these changes
Oct 21, 2023
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This commit fixes some counterintuitive behaviour when creating the middleware with a custom registry.
Previously, using a custom registry with additional metrics requires avoiding the RegisterAt function, which used only the prometheus.DefaultGatherer.
Given a *prometheus.Registry, instead of the more intuitive:
One would have to do this:
The change here detects when the
prometheus.Registereris also aprometheus.Gatherer, and then uses theprometheus.Gathererwhen callingRegisterAt.This change will not fix work in the case of a custom implementation of
prometheus.Registererwhen the that implementation is not also aprometheus.Gatherer, which is an unlikely situation for inexperienced users of prometheus.For the more common case of passing a
*prometheus.Registry, this change will provide a more intuitive experience.