Document the example usage of ConstLabels to register several GaugeFuncs
on the same metric name. Also reference it from the NewCounterFunc
documentation as it's similar.
Ref: https://github.com/prometheus/client_golang/pull/736
Signed-off-by: Oleg Zaytsev <mail@olegzaytsev.com>
Essentially, just don't try to set a status code and send any error
message in the body once metrics gathering has succeeded. At that
point, the most likely reason for errors is anyway that the client has
disconnected, in which sending an error is moot. The other possible
reason for an error is a problem during metrics encoding. This is
unlikely to happen (it's a coding error here in client_golang in any
case), and if it is happening, the odds are we have already sent
something to the ResponseWriter, which means we cannot set a status
code anymore. The doc comment for HTTPErrorOnError now describes these
circumstances explicitly and recommends to set a logger to report that
kind of error.
This should fix the reason for the infamous `superfluous
response.WriteHeader call` message.
Signed-off-by: beorn7 <beorn@grafana.com>
Introduces support for the new metadata endpoint from Prometheus. The new endpoint provides information independent of targets and collapses the unique combinations of HELP, TYPE and UNIT.
Fixes#705
Signed-off-by: gotjosh <josue@grafana.com>
Also, update the package documentation. The concerns about the global
registry aren't really valid anymore because promauto now also works
with custom registries.
The musings about the http.DefaultMux are more a digression and
shouldn't be in a doc comment.
Signed-off-by: beorn7 <beorn@grafana.com>
Interestingly, methods implicitly forwarded from embedded types are
detected by GoDoc if they are just one level deep. Embedded types in
the embedded type are not recognized. This commit therefore adds
explicit forwarding methods for Collect, Describe, and Reset.
Signed-off-by: beorn7 <beorn@grafana.com>
This is, sadly, the only way to avoid a breaking change. The cost is
that anyone using exemplars has to perform a type assertion. This is,
however, a common pattern where interfaces turn out to need additional
methods in a stable library or only some implementations can provide
the additional methods (AKA "interface upgrade").
Needless to say that in v2 of this library, we'll do things in a more
straight forward way.
Signed-off-by: beorn7 <beorn@grafana.com>
Simon Pasquier