Alerting: Send information about alert rule to data source in headers (#90344)

* add support of metadata to condition and adding it to request headers
* support for additional metadata when condition is built
* add additionall context to conditions: source and folder title
* add version
* use percent-encoding for header values

pkg/services/ngalert/schedule/alert_rule.go

@@ -357,7 +357,7 @@ func (a *alertRule) evaluate(ctx context.Context, f fingerprint, attempt int64,
 	start := a.clock.Now()
 
 	evalCtx := eval.NewContextWithPreviousResults(ctx, SchedulerUserFor(e.rule.OrgID), a.newLoadedMetricsReader(e.rule))
-	ruleEval, err := a.evalFactory.Create(evalCtx, e.rule.GetEvalCondition())
+	ruleEval, err := a.evalFactory.Create(evalCtx, e.rule.GetEvalCondition().WithSource("scheduler").WithFolder(e.folderTitle))
 	var results eval.Results
 	var dur time.Duration
 	if err != nil {

pkg/services/ngalert/schedule/recording_rule.go

@@ -272,7 +272,7 @@ func (r *recordingRule) tryEvaluation(ctx context.Context, ev *Evaluation, logge
 
 func (r *recordingRule) buildAndExecutePipeline(ctx context.Context, evalCtx eval.EvaluationContext, ev *Evaluation, logger log.Logger) (*backend.QueryDataResponse, error) {
 	start := r.clock.Now()
-	evaluator, err := r.evalFactory.Create(evalCtx, ev.rule.GetEvalCondition())
+	evaluator, err := r.evalFactory.Create(evalCtx, ev.rule.GetEvalCondition().WithSource("scheduler").WithFolder(ev.folderTitle))
 	if err != nil {
 		logger.Error("Failed to build rule evaluator", "error", err)
 		return nil, err