feat: expose Desc error through public Err() method #1902
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Adds a public
Err()method toDesctype to allow users to check if an error occurred during descriptor construction. Previously, the error field was private and inaccessible.Our use case is as follows:
Desc.Collect()method, we dynamically create aMetricusingNewConstMetric()to report the current value.However, if the
Descwas constructed with an error (for example, due to an invalid label name), that error remains hidden until the collector’sCollect()method is invoked for the first time.It would be much more practical if the Prometheus API exposed a method such as
Desc.Err(), which would return any error that occurred during the creation of theDesc. That's the motivation for the present PR.Signed-off-by: Yuri Nikolic durica.nikolic@grafana.com