Azure Monitor: Add logs query builder (#99055)

pkg/tsdb/azuremonitor/loganalytics/azure-log-analytics-datasource.go

@@ -28,6 +28,18 @@ import (
 	"github.com/grafana/grafana/pkg/tsdb/azuremonitor/utils"
 )
 
+// Returns tables with the `HasData` field set to true
+func filterTablesWithData(tables []types.MetadataTable) []types.MetadataTable {
+	filtered := []types.MetadataTable{}
+	for _, table := range tables {
+		if table.HasData {
+			filtered = append(filtered, table)
+		}
+	}
+
+	return filtered
+}
+
 func (e *AzureLogAnalyticsDatasource) ResourceRequest(rw http.ResponseWriter, req *http.Request, cli *http.Client) (http.ResponseWriter, error) {
 	if req.URL.Path == "/usage/basiclogs" {
 		newUrl := &url.URL{
@@ -36,7 +48,57 @@ func (e *AzureLogAnalyticsDatasource) ResourceRequest(rw http.ResponseWriter, re
 			Path:   "/v1/query",
 		}
 		return e.GetBasicLogsUsage(req.Context(), newUrl.String(), cli, rw, req.Body)
+	} else if strings.Contains(req.URL.Path, "/metadata") {
+		// Add necessary headers
+		req.Header.Set("Prefer", "metadata-format-v4,exclude-resourcetypes,exclude-customfunctions")
+		queryParams := req.URL.Query()
+		// Add necessary query params
+		queryParams.Add("select", "categories,solutions,tables,workspaces")
+		req.URL.RawQuery = queryParams.Encode()
+		resp, err := cli.Do(req)
+		if err != nil {
+			return nil, fmt.Errorf("failed to fetch metadata: %w", err)
+		}
+
+		defer func() {
+			if err := resp.Body.Close(); err != nil {
+				e.Logger.Warn("Failed to close response body for metadata request", "err", err)
+			}
+		}()
+
+		encoding := resp.Header.Get("Content-Encoding")
+		body, err := decode(encoding, resp.Body)
+		if err != nil {
+			return nil, fmt.Errorf("failed to read metadata response: %w", err)
+		}
+
+		if resp.StatusCode != http.StatusOK {
+			return nil, fmt.Errorf("metadata API error: %s", string(body))
+		}
+
+		var metadata types.AzureLogAnalyticsMetadata
+		err = json.Unmarshal(body, &metadata)
+		if err != nil {
+			return nil, fmt.Errorf("failed to unmarshal metadata response: %w", err)
+		}
+		metadata.Tables = filterTablesWithData(metadata.Tables)
+
+		responseBody, err := json.Marshal(metadata)
+		if err != nil {
+			return nil, fmt.Errorf("failed to marshal metadata response: %w", err)
+		}
+
+		rw.Header().Set("Content-Type", "application/json")
+		rw.WriteHeader(http.StatusOK)
+		_, err = rw.Write(responseBody)
+		if err != nil {
+			return nil, fmt.Errorf("failed to write metadata response: %w", err)
+		}
+
+		return rw, nil
 	}
+
+	// Default behavior for other requests
 	return e.Proxy.Do(rw, req, cli)
 }
 

pkg/tsdb/azuremonitor/loganalytics/utils.go

@@ -1,12 +1,16 @@
 package loganalytics
 
 import (
+	"compress/flate"
+	"compress/gzip"
 	"fmt"
+	"io"
 	"regexp"
 	"strconv"
 	"strings"
 	"time"
 
+	"github.com/andybalholm/brotli"
 	"github.com/grafana/grafana-plugin-sdk-go/backend"
 	"github.com/grafana/grafana-plugin-sdk-go/data"
 	"github.com/grafana/grafana/pkg/tsdb/azuremonitor/kinds/dataquery"
@@ -136,3 +140,40 @@ func ConvertTime(timeStamp string) (time.Time, error) {
 func GetDataVolumeRawQuery(table string) string {
 	return fmt.Sprintf("Usage \n| where DataType == \"%s\"\n| where IsBillable == true\n| summarize BillableDataGB = round(sum(Quantity) / 1000, 3)", table)
 }
+
+// This function handles various compression mechanisms that may have been used on a response body
+func decode(encoding string, original io.ReadCloser) ([]byte, error) {
+	var reader io.Reader
+	var err error
+	switch encoding {
+	case "gzip":
+		reader, err = gzip.NewReader(original)
+		if err != nil {
+			return nil, err
+		}
+		defer func() {
+			if err := reader.(io.ReadCloser).Close(); err != nil {
+				backend.Logger.Warn("Failed to close reader body", "err", err)
+			}
+		}()
+	case "deflate":
+		reader = flate.NewReader(original)
+		defer func() {
+			if err := reader.(io.ReadCloser).Close(); err != nil {
+				backend.Logger.Warn("Failed to close reader body", "err", err)
+			}
+		}()
+	case "br":
+		reader = brotli.NewReader(original)
+	case "":
+		reader = original
+	default:
+		return nil, fmt.Errorf("unexpected encoding type %v", err)
+	}
+
+	body, err := io.ReadAll(reader)
+	if err != nil {
+		return nil, err
+	}
+	return body, nil
+}