What is this feature?
This PR changes the behavior of the $value and .Value variables in alerting templating to be more compatible with Prometheus templating. When a single datasource is used in the alerting rule, these variables will now return the numeric value from the query instead of the evaluation string.
Why do we need this feature?
It makes Grafana templating more compatible with Prometheus templates. In Prometheus, $value returns the numeric value of the query, but in Grafana it's the evaluation string: [ var='A' labels={instance=instance1} value=81.234 ]. This is because in Grafana multiple datasources can be used in the alert rule, and it's not always possible to get a single value.
This change makes Grafana's behavior consistent with Prometheus when a single datasource is used, and in case when multiple datasources are used in the query, it keeps the old behaviour.
Both $value and .Value are not recommended to use (documentation), and it's better to use .Values instead.
* Migrate old alerting templates to use $labels
* Fix imports
* Add test coverage and separate rewriting to Go templates
* Fix lint
* Check for additional closing braces
* Add logging of invalid message templates
* Fix tests
* Small fixes
* Update comments
* Panic on empty token
* Use logtest.Fake
* Fix lint
* Allow for spaces in variable names by not tokenizing spaces
* Add template function to deduplicate Labels in a Value map
* Fix behavior of mapLookupString
* Reference deduplicated labels in migrated message template
* Fix behavior of deduplicateLabelsFunc
* Don't create variable for parent logger
* Add more tests for deduplicateLabelsFunc
* Remove unused function
* Apply suggestions from code review
Co-authored by: Yuri Tseretyan <yuriy.tseretyan@grafana.com>
* Give label val merge function better name
* Extract template migration and escape literal tokens
* Consolidate + simplify template migration
---------
Co-authored-by: William Wernert <william.wernert@grafana.com>
This commit changes the state package so that errors encountered while
expanding templates for custom labels and annotations are returned
from the function. This is not used at present, but will be used in the
future as we look at how to offer better feedback to users who don't
have access to logs, for example our customers who use Hosted Grafana.
This commit adds filterLabels, filterLabelsRe, removeLabels, and
removeLabelsRe functions to templates for custom labels and annotations.
It allows for use cases such as removing all private labels.
This commit changes the Data struct in template.go to use Labels
instead of map[string]string. It changes how labels are printed
when using {{ .Labels }} from map[foo:bar bar:baz] to
foo=bar, bar=baz.
This commit changes how labels are printed in templates for custom
annotations and labels from map[foo:bar bar:baz] to foo=bar, bar=baz.
Labels are comma separated, and sorted in increasing order.
This commit moves templating from the state package to a sub-package
called template. This sub-package will be the logical package for
future ease-of-use improvements to templating custom annotations
and labels.
Alexander Akhmetov
Ryan McKinley
George Robinson
Yuri Tseretyan
Steve Simpson
Serge Zaitsev