Alerting: check upstream response content type in lotex proxy (#34760) (#34842)

(cherry picked from commit 347273cdea)

pkg/services/ngalert/api/promql_compat.go

@@ -14,6 +14,7 @@ import (
 	"github.com/prometheus/prometheus/promql"
 	"github.com/prometheus/prometheus/promql/parser"
 
+	"github.com/grafana/grafana/pkg/api/response"
 	"github.com/grafana/grafana/pkg/util"
 )
 
@@ -112,9 +113,13 @@ func instantQueryResults(resp instantQueryResponse) (eval.Results, error) {
 	}
 }
 
-func instantQueryResultsExtractor(b []byte) (interface{}, error) {
+func instantQueryResultsExtractor(r *response.NormalResponse) (interface{}, error) {
+	contentType := r.Header().Get("Content-Type")
+	if !strings.Contains(contentType, "json") {
+		return nil, fmt.Errorf("unexpected content type from upstream. expected JSON, got %v", contentType)
+	}
 	var resp instantQueryResponse
-	err := json.Unmarshal(b, &resp)
+	err := json.Unmarshal(r.Body(), &resp)
 	if err != nil {
 		return nil, err
 	}

pkg/services/ngalert/api/util.go

@@ -91,7 +91,7 @@ func (p *AlertingProxy) withReq(
 	method string,
 	u *url.URL,
 	body io.Reader,
-	extractor func([]byte) (interface{}, error),
+	extractor func(*response.NormalResponse) (interface{}, error),
 	headers map[string]string,
 ) response.Response {
 	req, err := http.NewRequest(method, u.String(), body)
@@ -122,7 +122,7 @@ func (p *AlertingProxy) withReq(
 		return ErrResp(status, errors.New(errMessage), "")
 	}
 
-	t, err := extractor(resp.Body())
+	t, err := extractor(resp)
 	if err != nil {
 		return ErrResp(http.StatusInternalServerError, err, "")
 	}
@@ -135,9 +135,13 @@ func (p *AlertingProxy) withReq(
 	return response.JSON(status, b)
 }
 
-func yamlExtractor(v interface{}) func([]byte) (interface{}, error) {
-	return func(b []byte) (interface{}, error) {
-		decoder := yaml.NewDecoder(bytes.NewReader(b))
+func yamlExtractor(v interface{}) func(*response.NormalResponse) (interface{}, error) {
+	return func(resp *response.NormalResponse) (interface{}, error) {
+		contentType := resp.Header().Get("Content-Type")
+		if !strings.Contains(contentType, "yaml") {
+			return nil, fmt.Errorf("unexpected content type from upstream. expected YAML, got %v", contentType)
+		}
+		decoder := yaml.NewDecoder(bytes.NewReader(resp.Body()))
 		decoder.KnownFields(true)
 
 		err := decoder.Decode(v)
@@ -146,18 +150,22 @@ func yamlExtractor(v interface{}) func([]byte) (interface{}, error) {
 	}
 }
 
-func jsonExtractor(v interface{}) func([]byte) (interface{}, error) {
+func jsonExtractor(v interface{}) func(*response.NormalResponse) (interface{}, error) {
 	if v == nil {
 		// json unmarshal expects a pointer
 		v = &map[string]interface{}{}
 	}
-	return func(b []byte) (interface{}, error) {
-		return v, json.Unmarshal(b, v)
+	return func(resp *response.NormalResponse) (interface{}, error) {
+		contentType := resp.Header().Get("Content-Type")
+		if !strings.Contains(contentType, "json") {
+			return nil, fmt.Errorf("unexpected content type from upstream. expected JSON, got %v", contentType)
+		}
+		return v, json.Unmarshal(resp.Body(), v)
 	}
 }
 
-func messageExtractor(b []byte) (interface{}, error) {
-	return map[string]string{"message": string(b)}, nil
+func messageExtractor(resp *response.NormalResponse) (interface{}, error) {
+	return map[string]string{"message": string(resp.Body())}, nil
 }
 
 func validateCondition(c ngmodels.Condition, user *models.SignedInUser, skipCache bool, datasourceCache datasources.CacheService) error {

public/app/features/alerting/unified/api/ruler.ts

@@ -77,7 +77,10 @@ async function rulerGetRequest<T>(url: string, empty: T): Promise<T> {
   } catch (e) {
     if (e?.status === 404 || e?.data?.message?.includes('group does not exist')) {
       return empty;
-    } else if (e?.status === 500 && e?.data?.message?.includes('mapping values are not allowed in this context')) {
+    } else if (
+      e?.status === 500 &&
+      e?.data?.message?.includes('unexpected content type from upstream. expected YAML, got text/html')
+    ) {
       throw {
         ...e,
         data: {