parse error content

.changeset/neat-doors-smile.md

@@ -0,0 +1,5 @@
+---
+'grafana-infinity-datasource': minor
+---
+
+Parse HTTP response content in the event of HTTP error and send it back to browser as feedback

pkg/infinity/client.go

@@ -234,7 +234,7 @@ func (client *Client) req(ctx context.Context, url string, body io.Reader, setti
 		return nil, http.StatusInternalServerError, duration, errorsource.DownstreamError(fmt.Errorf("invalid response received for the URL %s", url), false)
 	}
 	if res.StatusCode >= http.StatusBadRequest {
-		err = fmt.Errorf("%w. %s", ErrUnsuccessfulHTTPResponseStatus, res.Status)
+		err = ParseErrorResponse(res)
 		// Infinity can query anything and users are responsible for ensuring that endpoint/auth is correct
 		// therefore any incoming error is considered downstream
 		return nil, res.StatusCode, duration, errorsource.DownstreamError(err, false)

pkg/infinity/http_error.go

@@ -0,0 +1,70 @@
+package infinity
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"mime"
+	"net/http"
+	"strings"
+)
+
+// HTTPResponseError represents an error response from an HTTP request.
+type HTTPResponseError struct {
+	StatusCode int    // HTTP status code
+	Message    string // Extracted error message from the HTTP response if any
+}
+
+// Error implements the error interface for HTTPResponseError.
+func (h *HTTPResponseError) Error() string {
+	err := ErrUnsuccessfulHTTPResponseStatus
+	if h.StatusCode >= http.StatusBadRequest {
+		err = errors.Join(err, fmt.Errorf("HTTP status code: %d %s", h.StatusCode, http.StatusText(h.StatusCode)))
+	}
+	if h.Message != "" {
+		err = errors.Join(err, fmt.Errorf("Error message from HTTP response: %s", h.Message))
+	}
+	return err.Error()
+}
+
+// ParseErrorResponse parses the HTTP response and extracts relevant error information.
+// It reads the response body and attempts to determine the error message and trace ID
+// based on the content type of the response. It handles various content types such as
+// JSON, plain text, and others. If the response body contains a recognizable error message
+// or trace ID, it populates the HTTPResponseError struct with this information.
+func ParseErrorResponse(res *http.Response) error {
+	err := &HTTPResponseError{}
+	if res == nil {
+		return err
+	}
+	err.StatusCode = res.StatusCode
+	bodyBytes, responseReadErr := io.ReadAll(res.Body)
+	if responseReadErr != nil {
+		return err
+	}
+	mediaType, _, _ := mime.ParseMediaType(res.Header.Get("Content-Type"))
+	mediaType = strings.ToLower(mediaType)
+	for _, key := range []string{"text/html", "text/xml", "application/html", "application/xml", "application/xhtml+xml", "application/rss+xml", "image/svg+xml", "application/octet-stream"} {
+		if strings.Contains(mediaType, key) {
+			return err
+		}
+	}
+	if strings.Contains(mediaType, "text/plain") {
+		if errMsg := strings.TrimSpace(string(bodyBytes)); errMsg != "" {
+			err.Message = errMsg
+		}
+		return err
+	}
+	var out map[string]any
+	unmarshalErr := json.Unmarshal(bodyBytes, &out)
+	if unmarshalErr != nil {
+		return err
+	}
+	for _, key := range []string{"error", "message", "status"} {
+		if errMsg, ok := out[key].(string); ok && errMsg != "" {
+			err.Message = errMsg
+		}
+	}
+	return err
+}

pkg/infinity/http_error_test.go

@@ -0,0 +1,91 @@
+package infinity_test
+
+import (
+	"io"
+	"net/http"
+	"strings"
+	"testing"
+
+	i "github.com/grafana/grafana-infinity-datasource/pkg/infinity"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestParseErrorResponse(t *testing.T) {
+	tests := []struct {
+		name    string
+		res     *http.Response
+		wantErr string
+	}{
+		{
+			name:    "No response",
+			wantErr: "unsuccessful HTTP response",
+		},
+		{
+			name: "Internal server error with plain text response and no mime header",
+			res: &http.Response{
+				StatusCode: http.StatusInternalServerError,
+				Body:       io.NopCloser(strings.NewReader("foo")),
+			},
+			wantErr: "unsuccessful HTTP response\nHTTP status code: 500 Internal Server Error",
+		},
+		{
+			name: "Internal server error with text error message and mime header",
+			res: &http.Response{
+				StatusCode: http.StatusInternalServerError,
+				Header:     map[string][]string{"Content-Type": {"text/plain"}},
+				Body:       io.NopCloser(strings.NewReader("A text error message")),
+			},
+			wantErr: "unsuccessful HTTP response\nHTTP status code: 500 Internal Server Error\nError message from HTTP response: A text error message",
+		},
+		{
+			name: "Internal server error with HTML content",
+			res: &http.Response{
+				StatusCode: http.StatusInternalServerError,
+				Header:     map[string][]string{"Content-Type": {"text/html"}},
+				Body:       io.NopCloser(strings.NewReader("<>html</>")),
+			},
+			wantErr: "unsuccessful HTTP response\nHTTP status code: 500 Internal Server Error",
+		},
+		{
+			name: "Internal server error with empty JSON object",
+			res: &http.Response{
+				StatusCode: http.StatusInternalServerError,
+				Body:       io.NopCloser(strings.NewReader("{}")),
+			},
+			wantErr: "unsuccessful HTTP response\nHTTP status code: 500 Internal Server Error",
+		},
+		{
+			name: "Internal server error with empty JSON array",
+			res: &http.Response{
+				StatusCode: http.StatusInternalServerError,
+				Body:       io.NopCloser(strings.NewReader("[]")),
+			},
+			wantErr: "unsuccessful HTTP response\nHTTP status code: 500 Internal Server Error",
+		},
+		{
+			name: "Internal server error with JSON message",
+			res: &http.Response{
+				StatusCode: http.StatusInternalServerError,
+				Body:       io.NopCloser(strings.NewReader(`{ "message" : "foo" }`)),
+			},
+			wantErr: "unsuccessful HTTP response\nHTTP status code: 500 Internal Server Error\nError message from HTTP response: foo",
+		},
+		{
+			name: "Invalid JSON content response",
+			res: &http.Response{
+				StatusCode: http.StatusInternalServerError,
+				Body:       io.NopCloser(strings.NewReader(`{ "error" : "foo", "traceId" : "bar" `)),
+			},
+			wantErr: "unsuccessful HTTP response\nHTTP status code: 500 Internal Server Error",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			gotErr := i.ParseErrorResponse(tt.res)
+			require.NotNil(t, gotErr)
+			require.NotNil(t, tt.wantErr)
+			assert.Equal(t, tt.wantErr, gotErr.Error())
+		})
+	}
+}

pkg/testsuite/handler_querydata_errors_test.go

@@ -42,8 +42,7 @@ func TestErrors(t *testing.T) {
 			}, *client, map[string]string{}, backend.PluginContext{})
 			require.NotNil(t, res.Error)
 			require.Equal(t, backend.ErrorSourceDownstream, res.ErrorSource)
-			require.ErrorIs(t, res.Error, infinity.ErrUnsuccessfulHTTPResponseStatus)
-			require.Equal(t, "error while performing the infinity query. unsuccessful HTTP response. 403 Forbidden", res.Error.Error())
+			require.Equal(t, "error while performing the infinity query. unsuccessful HTTP response\nHTTP status code: 403 Forbidden", res.Error.Error())
 		})
 		t.Run("fail with incorrect response from server", func(t *testing.T) {
 			server := httptest.NewUnstartedServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

pkg/testsuite/handler_querydata_test.go

@@ -112,7 +112,7 @@ func TestAuthentication(t *testing.T) {
 			metaData := res.Frames[0].Meta.Custom.(*infinity.CustomMeta)
 			require.NotNil(t, res.Error)
 			require.NotNil(t, metaData)
-			require.Equal(t, "unsuccessful HTTP response. 401 Unauthorized", metaData.Error)
+			require.Equal(t, "unsuccessful HTTP response\nHTTP status code: 401 Unauthorized\nError message from HTTP response: UnAuthorized", metaData.Error)
 			require.Equal(t, http.StatusUnauthorized, metaData.ResponseCodeFromServer)
 		})
 	})
@@ -352,7 +352,7 @@ func TestAuthentication(t *testing.T) {
 				}`, "http://httpbin.org/digest-auth/auth/foo/bar/MD5")),
 			}, *client, map[string]string{}, backend.PluginContext{})
 			require.NotNil(t, res.Error)
-			require.Equal(t, "error while performing the infinity query. unsuccessful HTTP response. 401 UNAUTHORIZED", res.Error.Error())
+			require.Equal(t, "error while performing the infinity query. unsuccessful HTTP response\nHTTP status code: 401 Unauthorized", res.Error.Error())
 		})
 		t.Run("should fail with incorrect auth method", func(t *testing.T) {
 			client, err := infinity.NewClient(context.TODO(), models.InfinitySettings{
@@ -370,7 +370,7 @@ func TestAuthentication(t *testing.T) {
 				}`, "http://httpbin.org/digest-auth/auth/foo/bar/MD5")),
 			}, *client, map[string]string{}, backend.PluginContext{})
 			require.NotNil(t, res.Error)
-			require.Equal(t, "error while performing the infinity query. unsuccessful HTTP response. 401 UNAUTHORIZED", res.Error.Error())
+			require.Equal(t, "error while performing the infinity query. unsuccessful HTTP response\nHTTP status code: 401 Unauthorized", res.Error.Error())
 		})
 	})
 }