backport of commit 48889f33ec94b1f6f58357b64536662d5b14b9ec (#17746)

Co-authored-by: Chris Chapman <cchapman@hashicorp.com>

agent/hcp/client/metrics_client.go

@@ -32,6 +32,10 @@ const (
 	// defaultRetryMax is set to 0 to turn off retry functionality, until dynamic configuration is possible.
 	// This is to circumvent any spikes in load that may cause or exacerbate server-side issues for now.
 	defaultRetryMax = 0
+
+	// defaultErrRespBodyLength refers to the max character length of the body on a failure to export metrics.
+	// anything beyond we will truncate.
+	defaultErrRespBodyLength = 100
 )
 
 // MetricsClient exports Consul metrics in OTLP format to the HCP Telemetry Gateway.
@@ -150,8 +154,18 @@ func (o *otlpClient) ExportMetrics(ctx context.Context, protoMetrics *metricpb.R
 	}
 
 	if resp.StatusCode != http.StatusOK {
-		return fmt.Errorf("failed to export metrics: code %d: %s", resp.StatusCode, string(body))
+		truncatedBody := truncate(respData.String(), defaultErrRespBodyLength)
+		return fmt.Errorf("failed to export metrics: code %d: %s", resp.StatusCode, truncatedBody)
 	}
 
 	return nil
 }
+
+func truncate(text string, width uint) string {
+	if len(text) <= int(width) {
+		return text
+	}
+	r := []rune(text)
+	trunc := r[:width]
+	return string(trunc) + "..."
+}

agent/hcp/client/metrics_client_test.go

@@ -3,6 +3,7 @@ package client
 import (
 	"context"
 	"fmt"
+	"math/rand"
 	"net/http"
 	"net/http/httptest"
 	"testing"
@@ -64,10 +65,21 @@ func TestNewMetricsClient(t *testing.T) {
 	}
 }
 
+var letterRunes = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZäöüÄÖÜ世界")
+
+func randStringRunes(n int) string {
+	b := make([]rune, n)
+	for i := range b {
+		b[i] = letterRunes[rand.Intn(len(letterRunes))]
+	}
+	return string(b)
+}
+
 func TestExportMetrics(t *testing.T) {
 	for name, test := range map[string]struct {
-		wantErr string
-		status  int
+		wantErr        string
+		status         int
+		largeBodyError bool
 	}{
 		"success": {
 			status: http.StatusOK,
@@ -76,8 +88,14 @@ func TestExportMetrics(t *testing.T) {
 			status:  http.StatusBadRequest,
 			wantErr: "failed to export metrics: code 400",
 		},
+		"failsWithNonRetryableErrorWithLongError": {
+			status:         http.StatusBadRequest,
+			wantErr:        "failed to export metrics: code 400",
+			largeBodyError: true,
+		},
 	} {
 		t.Run(name, func(t *testing.T) {
+			randomBody := randStringRunes(1000)
 			srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 				require.Equal(t, r.Header.Get("content-type"), "application/x-protobuf")
 				require.Equal(t, r.Header.Get("x-hcp-resource-id"), testResourceID)
@@ -91,7 +109,12 @@ func TestExportMetrics(t *testing.T) {
 
 				w.Header().Set("Content-Type", "application/x-protobuf")
 				w.WriteHeader(test.status)
-				w.Write(bytes)
+				if test.largeBodyError {
+					w.Write([]byte(randomBody))
+				} else {
+					w.Write(bytes)
+				}
+
 			}))
 			defer srv.Close()
 
@@ -105,6 +128,10 @@ func TestExportMetrics(t *testing.T) {
 			if test.wantErr != "" {
 				require.Error(t, err)
 				require.Contains(t, err.Error(), test.wantErr)
+				if test.largeBodyError {
+					truncatedBody := truncate(randomBody, defaultErrRespBodyLength)
+					require.Contains(t, err.Error(), truncatedBody)
+				}
 				return
 			}
 
@@ -112,3 +139,37 @@ func TestExportMetrics(t *testing.T) {
 		})
 	}
 }
+
+func TestTruncate(t *testing.T) {
+	for name, tc := range map[string]struct {
+		body         string
+		expectedSize int
+	}{
+		"ZeroSize": {
+			body:         "",
+			expectedSize: 0,
+		},
+		"LessThanSize": {
+			body:         "foobar",
+			expectedSize: 6,
+		},
+		"defaultSize": {
+			body:         "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Duis vel tincidunt nunc, sed tristique risu",
+			expectedSize: 100,
+		},
+		"greaterThanSize": {
+			body:         "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Duis vel tincidunt nunc, sed tristique risus",
+			expectedSize: 103,
+		},
+		"greaterThanSizeWithUnicode": {
+			body:         randStringRunes(1000),
+			expectedSize: 103,
+		},
+	} {
+		t.Run(name, func(t *testing.T) {
+			truncatedBody := truncate(tc.body, defaultErrRespBodyLength)
+			truncatedRunes := []rune(truncatedBody)
+			require.Equal(t, len(truncatedRunes), tc.expectedSize)
+		})
+	}
+}