Alerting: Refactor Evaluator (#51673)

* AlertRule to return condition
* update ConditionEval to not return an error because it's always nil
* make getExprRequest private
* refactor executeCondition to just converter and move execution to the ConditionEval as this makes code more readable.
* log error if results have errors
* change signature of evaluate function to not return an error

pkg/services/ngalert/eval/eval.go

@@ -28,7 +28,7 @@ import (
 //go:generate mockery --name Evaluator --structname FakeEvaluator --inpackage --filename evaluator_mock.go --with-expecter
 type Evaluator interface {
 	// ConditionEval executes conditions and evaluates the result.
-	ConditionEval(condition *models.Condition, now time.Time) (Results, error)
+	ConditionEval(condition models.Condition, now time.Time) Results
 	// QueriesAndExpressionsEval executes queries and expressions and returns the result.
 	QueriesAndExpressionsEval(orgID int64, data []models.AlertQuery, now time.Time) (*backend.QueryDataResponse, error)
 }
@@ -89,6 +89,15 @@ type ExecutionResults struct {
 // Results is a slice of evaluated alert instances states.
 type Results []Result
 
+func (evalResults Results) HasErrors() bool {
+	for _, r := range evalResults {
+		if r.State == Error {
+			return true
+		}
+	}
+	return false
+}
+
 // Result contains the evaluated State of an alert instance
 // identified by its labels.
 type Result struct {
@@ -153,8 +162,8 @@ type AlertExecCtx struct {
 	Ctx context.Context
 }
 
-// GetExprRequest validates the condition, gets the datasource information and creates an expr.Request from it.
-func GetExprRequest(ctx AlertExecCtx, data []models.AlertQuery, now time.Time, dsCacheService datasources.CacheService, secretsService secrets.Service) (*expr.Request, error) {
+// getExprRequest validates the condition, gets the datasource information and creates an expr.Request from it.
+func getExprRequest(ctx AlertExecCtx, data []models.AlertQuery, now time.Time, dsCacheService datasources.CacheService, secretsService secrets.Service) (*expr.Request, error) {
 	req := &expr.Request{
 		OrgId: ctx.OrgID,
 		Headers: map[string]string{
@@ -166,8 +175,7 @@ func GetExprRequest(ctx AlertExecCtx, data []models.AlertQuery, now time.Time, d
 
 	datasources := make(map[string]*datasources.DataSource, len(data))
 
-	for i := range data {
-		q := data[i]
+	for _, q := range data {
 		model, err := q.GetModel()
 		if err != nil {
 			return nil, fmt.Errorf("failed to get query model: %w", err)
@@ -259,12 +267,7 @@ type NumberValueCapture struct {
 	Value  *float64
 }
 
-func executeCondition(ctx AlertExecCtx, c *models.Condition, now time.Time, exprService *expr.Service, dsCacheService datasources.CacheService, secretsService secrets.Service) ExecutionResults {
-	execResp, err := executeQueriesAndExpressions(ctx, c.Data, now, exprService, dsCacheService, secretsService)
-	if err != nil {
-		return ExecutionResults{Error: err}
-	}
-
+func queryDataResponseToExecutionResults(c models.Condition, execResp *backend.QueryDataResponse) ExecutionResults {
 	// eval captures for the '__value_string__' annotation and the Value property of the API response.
 	captures := make([]NumberValueCapture, 0, len(execResp.Responses))
 	captureVal := func(refID string, labels data.Labels, value *float64) {
@@ -356,7 +359,7 @@ func executeQueriesAndExpressions(ctx AlertExecCtx, data []models.AlertQuery, no
 		}
 	}()
 
-	queryDataReq, err := GetExprRequest(ctx, data, now, dsCacheService, secretsService)
+	queryDataReq, err := getExprRequest(ctx, data, now, dsCacheService, secretsService)
 	if err != nil {
 		return nil, err
 	}
@@ -564,8 +567,6 @@ func (evalResults Results) AsDataFrame() data.Frame {
 		labelColumns = append(labelColumns, k)
 	}
 
-	labelColumns = sort.StringSlice(labelColumns)
-
 	frame := data.NewFrame("evaluation results")
 	for _, lKey := range labelColumns {
 		frame.Fields = append(frame.Fields, data.NewField(lKey, nil, make([]string, fieldLen)))
@@ -591,16 +592,15 @@ func (evalResults Results) AsDataFrame() data.Frame {
 }
 
 // ConditionEval executes conditions and evaluates the result.
-func (e *evaluatorImpl) ConditionEval(condition *models.Condition, now time.Time) (Results, error) {
-	alertCtx, cancelFn := context.WithTimeout(context.Background(), e.cfg.UnifiedAlerting.EvaluationTimeout)
-	defer cancelFn()
-
-	alertExecCtx := AlertExecCtx{OrgID: condition.OrgID, Ctx: alertCtx, ExpressionsEnabled: e.cfg.ExpressionsEnabled, Log: e.log}
-
-	execResult := executeCondition(alertExecCtx, condition, now, e.expressionService, e.dataSourceCache, e.secretsService)
-
-	evalResults := evaluateExecutionResult(execResult, now)
-	return evalResults, nil
+func (e *evaluatorImpl) ConditionEval(condition models.Condition, now time.Time) Results {
+	execResp, err := e.QueriesAndExpressionsEval(condition.OrgID, condition.Data, now)
+	var execResults ExecutionResults
+	if err != nil {
+		execResults = ExecutionResults{Error: err}
+	} else {
+		execResults = queryDataResponseToExecutionResults(condition, execResp)
+	}
+	return evaluateExecutionResult(execResults, now)
 }
 
 // QueriesAndExpressionsEval executes queries and expressions and returns the result.