Fix headers in Druid DS (#97)

Co-authored-by: Jakub Michalak <[email protected]>

Author: 2 people

pkg/tsdb/druid/druid.go

@@ -11,6 +11,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/Knetic/govaluate"
 	"github.com/bitly/go-simplejson"
 	"github.com/grafadruid/go-druid"
 	druidquerybuilder "github.com/grafadruid/go-druid/builder"
@@ -183,7 +184,10 @@ func (ds *Service) CallResource(ctx context.Context, req *backend.CallResourceRe
 	default:
 		body = "Path not supported"
 	}
-	resp := &backend.CallResourceResponse{Status: code}
+	resp := &backend.CallResourceResponse{
+		Headers: map[string][]string{},
+		Status:  code,
+	}
 	resp.Body, err = json.Marshal(body)
 	sender.Send(resp)
 	return nil
@@ -440,6 +444,9 @@ func (ds *Service) prepareQuery(qry []byte, s *druidInstanceSettings) (druidquer
 			defaultQueryContext,
 			ds.prepareQueryContext(queryContextParameters.([]interface{})))
 	}
+	if g, ok := q.Builder["granularity"].(map[string]any); ok {
+		q.Builder["granularity"] = resolveGranularity(g)
+	}
 	jsonQuery, err := json.Marshal(q.Builder)
 	if err != nil {
 		return nil, nil, err
@@ -449,6 +456,28 @@ func (ds *Service) prepareQuery(qry []byte, s *druidInstanceSettings) (druidquer
 	return query, mergeSettings(s.defaultQuerySettings, q.Settings), err
 }
 
+func resolveGranularity(m map[string]any) map[string]any {
+	// granularity is optional, so return early if not set and is of wrong type
+	if m == nil || m["type"] != "duration" {
+		return m
+	}
+	expr, ok := m["duration"].(string)
+	if !ok {
+		return m
+	}
+
+	eval, err := govaluate.NewEvaluableExpression(expr)
+	if err != nil {
+		return m
+	}
+	result, err := eval.Evaluate(nil)
+	if err != nil {
+		return m
+	}
+	m["duration"] = result
+	return m
+}
+
 func (ds *Service) prepareQueryContext(parameters []interface{}) map[string]interface{} {
 	ctx := make(map[string]interface{})
 	for _, parameter := range parameters {