Loki: Handle data source configs with path in the url (#50971)

* loki: fixed param-name

* loki: handle datasource configs with path in the url

* lint fix

pkg/tsdb/loki/api.go

@@ -8,6 +8,7 @@ import (
 	"io"
 	"net/http"
 	"net/url"
+	"path"
 	"strconv"
 
 	"github.com/grafana/grafana-plugin-sdk-go/data"
@@ -68,12 +69,12 @@ func makeDataRequest(ctx context.Context, lokiDsUrl string, query lokiQuery, hea
 			//     precise, as Loki does not support step with float number
 			//     and time-specifier, like "1.5s"
 			qs.Set("step", fmt.Sprintf("%dms", query.Step.Milliseconds()))
-			lokiUrl.Path = "/loki/api/v1/query_range"
+			lokiUrl.Path = path.Join(lokiUrl.Path, "/loki/api/v1/query_range")
 		}
 	case QueryTypeInstant:
 		{
 			qs.Set("time", strconv.FormatInt(query.End.UnixNano(), 10))
-			lokiUrl.Path = "/loki/api/v1/query"
+			lokiUrl.Path = path.Join(lokiUrl.Path, "/loki/api/v1/query")
 		}
 	default:
 		return nil, fmt.Errorf("invalid QueryType: %v", query.QueryType)
@@ -169,18 +170,22 @@ func (api *LokiAPI) DataQuery(ctx context.Context, query lokiQuery) (data.Frames
 	return res.Frames, nil
 }
 
-func makeRawRequest(ctx context.Context, lokiDsUrl string, resourceURL string, headers map[string]string) (*http.Request, error) {
+func makeRawRequest(ctx context.Context, lokiDsUrl string, resourcePath string, headers map[string]string) (*http.Request, error) {
 	lokiUrl, err := url.Parse(lokiDsUrl)
 	if err != nil {
 		return nil, err
 	}
 
-	url, err := lokiUrl.Parse(resourceURL)
+	resourceUrl, err := url.Parse(resourcePath)
 	if err != nil {
 		return nil, err
 	}
 
-	req, err := http.NewRequestWithContext(ctx, "GET", url.String(), nil)
+	// we take the path and the query-string only
+	lokiUrl.RawQuery = resourceUrl.RawQuery
+	lokiUrl.Path = path.Join(lokiUrl.Path, resourceUrl.Path)
+
+	req, err := http.NewRequestWithContext(ctx, "GET", lokiUrl.String(), nil)
 
 	if err != nil {
 		return nil, err
@@ -191,8 +196,8 @@ func makeRawRequest(ctx context.Context, lokiDsUrl string, resourceURL string, h
 	return req, nil
 }
 
-func (api *LokiAPI) RawQuery(ctx context.Context, resourceURL string) ([]byte, error) {
-	req, err := makeRawRequest(ctx, api.url, resourceURL, api.headers)
+func (api *LokiAPI) RawQuery(ctx context.Context, resourcePath string) ([]byte, error) {
+	req, err := makeRawRequest(ctx, api.url, resourcePath, api.headers)
 	if err != nil {
 		return nil, err
 	}

pkg/tsdb/loki/api_mock.go

@@ -33,9 +33,13 @@ func (mockedRT *mockedRoundTripper) RoundTrip(req *http.Request) (*http.Response
 }
 
 func makeMockedAPI(statusCode int, contentType string, responseBytes []byte, requestCallback mockRequestCallback) *LokiAPI {
+	return makeMockedAPIWithUrl("http://localhost:9999", statusCode, contentType, responseBytes, requestCallback)
+}
+
+func makeMockedAPIWithUrl(url string, statusCode int, contentType string, responseBytes []byte, requestCallback mockRequestCallback) *LokiAPI {
 	client := http.Client{
 		Transport: &mockedRoundTripper{statusCode: statusCode, contentType: contentType, responseBytes: responseBytes, requestCallback: requestCallback},
 	}
 
-	return newLokiAPI(&client, "http://localhost:9999", log.New("test"), nil)
+	return newLokiAPI(&client, url, log.New("test"), nil)
 }

pkg/tsdb/loki/api_test.go

@@ -0,0 +1,126 @@
+package loki
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestApiLogVolume(t *testing.T) {
+	response := []byte(`
+	{
+		"status": "success",
+		"data": {
+			"resultType" : "matrix",
+			"result": []
+		}
+	}
+	`)
+
+	t.Run("log-volume queries should set log-volume http header", func(t *testing.T) {
+		called := false
+		api := makeMockedAPI(200, "application/json", response, func(req *http.Request) {
+			called = true
+			require.Equal(t, "Source=logvolhist", req.Header.Get("X-Query-Tags"))
+		})
+
+		_, err := api.DataQuery(context.Background(), lokiQuery{Expr: "", VolumeQuery: true, QueryType: QueryTypeRange})
+		require.NoError(t, err)
+		require.True(t, called)
+	})
+
+	t.Run("non-log-volume queries should not set log-volume http header", func(t *testing.T) {
+		called := false
+		api := makeMockedAPI(200, "application/json", response, func(req *http.Request) {
+			called = true
+			require.Equal(t, "", req.Header.Get("X-Query-Tags"))
+		})
+
+		_, err := api.DataQuery(context.Background(), lokiQuery{Expr: "", VolumeQuery: false, QueryType: QueryTypeRange})
+		require.NoError(t, err)
+		require.True(t, called)
+	})
+}
+
+func TestApiUrlHandling(t *testing.T) {
+	response := []byte(`
+	{
+		"status": "success",
+		"data": {
+			"resultType" : "matrix",
+			"result": []
+		}
+	}
+	`)
+
+	queryTestData := []struct {
+		name        string
+		dsUrl       string
+		queryPrefix string
+		metaUrl     string
+	}{
+		{
+			name:        "no path in datasource-config",
+			dsUrl:       "http://localhost:3100",
+			queryPrefix: "http://localhost:3100/loki/api/v1/query_range?",
+			metaUrl:     "http://localhost:3100/loki/api/v1/labels?start=1&end=2",
+		},
+		{
+			name:        "just a slash path in datasource-config",
+			dsUrl:       "http://localhost:3100/",
+			queryPrefix: "http://localhost:3100/loki/api/v1/query_range?",
+			metaUrl:     "http://localhost:3100/loki/api/v1/labels?start=1&end=2",
+		},
+		{
+			name:        "when path-without-end-slash in datasource-config",
+			dsUrl:       "http://localhost:3100/a/b/c",
+			queryPrefix: "http://localhost:3100/a/b/c/loki/api/v1/query_range?",
+			metaUrl:     "http://localhost:3100/a/b/c/loki/api/v1/labels?start=1&end=2",
+		},
+		{
+			name:        "path-with-end-slash in datasource-config",
+			dsUrl:       "http://localhost:3100/a/b/c/",
+			queryPrefix: "http://localhost:3100/a/b/c/loki/api/v1/query_range?",
+			metaUrl:     "http://localhost:3100/a/b/c/loki/api/v1/labels?start=1&end=2",
+		},
+	}
+
+	for _, test := range queryTestData {
+		t.Run("Loki should build the query URL correctly when "+test.name, func(t *testing.T) {
+			called := false
+			api := makeMockedAPIWithUrl(test.dsUrl, 200, "application/json", response, func(req *http.Request) {
+				called = true
+				urlString := req.URL.String()
+				wantedPrefix := test.queryPrefix
+				failMessage := fmt.Sprintf(`wanted prefix: [%s], got string [%s]`, wantedPrefix, urlString)
+				require.True(t, strings.HasPrefix(urlString, wantedPrefix), failMessage)
+			})
+
+			query := lokiQuery{
+				QueryType: QueryTypeRange,
+			}
+
+			_, err := api.DataQuery(context.Background(), query)
+			require.NoError(t, err)
+			require.True(t, called)
+		})
+	}
+
+	for _, test := range queryTestData {
+		t.Run("Loki should build the metadata query URL correctly when "+test.name, func(t *testing.T) {
+			called := false
+			api := makeMockedAPIWithUrl(test.dsUrl, 200, "application/json", response, func(req *http.Request) {
+				called = true
+				require.Equal(t, test.metaUrl, req.URL.String())
+			})
+
+			_, err := api.RawQuery(context.Background(), "/loki/api/v1/labels?start=1&end=2")
+			require.NoError(t, err)
+			require.True(t, called)
+		})
+	}
+}