Handle 'allow_no_indices' and 'ignore_unavailable' query params for /…

…field_caps (#128)

Fixes data view management/settings panel in Kibana. Since we don't
close/open indices, both options behave the same

Depends on:
- #126

quesma/quesma/field_caps.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"fmt"
 	"mitmproxy/quesma/clickhouse"
 	"mitmproxy/quesma/elasticsearch"
 	"mitmproxy/quesma/model"
@@ -182,6 +183,18 @@ func handleFieldCapsIndex(ctx context.Context, indexes []string, tables clickhou
 	return json.Marshal(fieldCapsResponse)
 }
 
+func EmptyFieldCapsResponse() []byte {
+	var response = model.FieldCapsResponse{
+		Fields:  make(map[string]map[string]model.FieldCapability),
+		Indices: []string{},
+	}
+	if serialized, err := json.Marshal(response); err != nil {
+		panic(fmt.Sprintf("Failed to serialize empty field caps response: %v, this should never happen", err))
+	} else {
+		return serialized
+	}
+}
+
 func isInternalColumn(col *clickhouse.Column) bool {
 	return col.Name == clickhouse.AttributesKeyColumn || col.Name == clickhouse.AttributesValueColumn
 }

quesma/quesma/router.go

@@ -220,10 +220,13 @@ func configureRouter(cfg config.QuesmaConfiguration, lm *clickhouse.LogManager,
 		return elasticsearchQueryResult(string(responseBody), httpOk), nil
 	})
 
-	router.RegisterPathMatcher(routes.FieldCapsPath, []string{"GET", "POST"}, matchedAgainstPattern(cfg), func(ctx context.Context, body string, _ string, params map[string]string, _ http.Header, _ url.Values) (*mux.Result, error) {
+	router.RegisterPathMatcher(routes.FieldCapsPath, []string{"GET", "POST"}, matchedAgainstPattern(cfg), func(ctx context.Context, body string, _ string, params map[string]string, _ http.Header, queryParams url.Values) (*mux.Result, error) {
 		responseBody, err := handleFieldCaps(ctx, params["index"], []byte(body), lm)
 		if err != nil {
 			if errors.Is(errIndexNotExists, err) {
+				if queryParams.Get("allow_no_indices") == "true" || queryParams.Get("ignore_unavailable") == "true" {
+					return elasticsearchQueryResult(string(EmptyFieldCapsResponse()), httpOk), nil
+				}
 				return &mux.Result{StatusCode: 404}, nil
 			} else {
 				return nil, err