[exporter/otlphttp] added support for configurable telemetry encoding (…

…#9276)

**Description:**
This PR adds support for encoding configuration in the `otlphttp`
exporter.

**Link to tracking Issue:** 
#6945

**Testing:** 
Updated existing tests, and added relevant tests 

**Documentation:** 
Updated the `otlphttp` docs to include the new configuration option.

---------

Co-authored-by: Yang Song <songy23@users.noreply.github.com>

.chloggen/otlphttp-json-encoding.yaml

@@ -0,0 +1,25 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: otlphttpexporter
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add support for json content encoding when exporting telemetry
+
+# One or more tracking issues or pull requests related to the change
+issues: [6945]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

exporter/otlphttpexporter/README.md

@@ -37,6 +37,7 @@ The following settings can be optionally configured:
 - `timeout` (default = 30s): HTTP request time limit. For details see https://golang.org/pkg/net/http/#Client
 - `read_buffer_size` (default = 0): ReadBufferSize for HTTP client.
 - `write_buffer_size` (default = 512 * 1024): WriteBufferSize for HTTP client.
+- `encoding` (default = proto): The encoding to use for the messages (valid options: `proto`, `json`)
 
 Example:
 
@@ -55,5 +56,14 @@ exporters:
     compression: none
 ```
 
+By default `proto` encoding is used, to change the content encoding of the message configure it as follows:
+
+```yaml
+exporters:
+  otlphttp:
+    ...
+    encoding: json
+```
+
 The full list of settings exposed for this exporter are documented [here](./config.go)
 with detailed sample configurations [here](./testdata/config.yaml).

exporter/otlphttpexporter/config.go

@@ -4,14 +4,45 @@
 package otlphttpexporter // import "go.opentelemetry.io/collector/exporter/otlphttpexporter"
 
 import (
+	"encoding"
 	"errors"
+	"fmt"
 
 	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/config/confighttp"
 	"go.opentelemetry.io/collector/config/configretry"
 	"go.opentelemetry.io/collector/exporter/exporterhelper"
 )
 
+// EncodingType defines the type for content encoding
+type EncodingType string
+
+const (
+	EncodingProto EncodingType = "proto"
+	EncodingJSON  EncodingType = "json"
+)
+
+var _ encoding.TextUnmarshaler = (*EncodingType)(nil)
+
+// UnmarshalText unmarshalls text to an EncodingType.
+func (e *EncodingType) UnmarshalText(text []byte) error {
+	if e == nil {
+		return errors.New("cannot unmarshal to a nil *EncodingType")
+	}
+
+	str := string(text)
+	switch str {
+	case string(EncodingProto):
+		*e = EncodingProto
+	case string(EncodingJSON):
+		*e = EncodingJSON
+	default:
+		return fmt.Errorf("invalid encoding type: %s", str)
+	}
+
+	return nil
+}
+
 // Config defines configuration for OTLP/HTTP exporter.
 type Config struct {
 	confighttp.ClientConfig `mapstructure:",squash"`     // squash ensures fields are correctly decoded in embedded struct.
@@ -26,6 +57,9 @@ type Config struct {
 
 	// The URL to send logs to. If omitted the Endpoint + "/v1/logs" will be used.
 	LogsEndpoint string `mapstructure:"logs_endpoint"`
+
+	// The encoding to export telemetry (default: "proto")
+	Encoding EncodingType `mapstructure:"encoding"`
 }
 
 var _ component.Config = (*Config)(nil)

exporter/otlphttpexporter/config_test.go

@@ -51,6 +51,7 @@ func TestUnmarshalConfig(t *testing.T) {
 				NumConsumers: 2,
 				QueueSize:    10,
 			},
+			Encoding: EncodingProto,
 			ClientConfig: confighttp.ClientConfig{
 				Headers: map[string]configopaque.String{
 					"can you have a . here?": "F0000000-0000-0000-0000-000000000000",
@@ -73,3 +74,57 @@ func TestUnmarshalConfig(t *testing.T) {
 			},
 		}, cfg)
 }
+
+func TestUnmarshalConfigInvalidEncoding(t *testing.T) {
+	cm, err := confmaptest.LoadConf(filepath.Join("testdata", "bad_invalid_encoding.yaml"))
+	require.NoError(t, err)
+	factory := NewFactory()
+	cfg := factory.CreateDefaultConfig()
+	assert.Error(t, component.UnmarshalConfig(cm, cfg))
+}
+
+func TestUnmarshalEncoding(t *testing.T) {
+	tests := []struct {
+		name          string
+		encodingBytes []byte
+		expected      EncodingType
+		shouldError   bool
+	}{
+		{
+			name:          "UnmarshalEncodingProto",
+			encodingBytes: []byte("proto"),
+			expected:      EncodingProto,
+			shouldError:   false,
+		},
+		{
+			name:          "UnmarshalEncodingJson",
+			encodingBytes: []byte("json"),
+			expected:      EncodingJSON,
+			shouldError:   false,
+		},
+		{
+			name:          "UnmarshalEmptyEncoding",
+			encodingBytes: []byte(""),
+			shouldError:   true,
+		},
+		{
+			name:          "UnmarshalInvalidEncoding",
+			encodingBytes: []byte("invalid"),
+			shouldError:   true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var encoding EncodingType
+			err := encoding.UnmarshalText(tt.encodingBytes)
+
+			if tt.shouldError {
+				assert.Error(t, err)
+			} else {
+				assert.NoError(t, err)
+				assert.Equal(t, tt.expected, encoding)
+			}
+		})
+	}
+}

exporter/otlphttpexporter/factory.go

@@ -36,6 +36,7 @@ func createDefaultConfig() component.Config {
 	return &Config{
 		RetryConfig: configretry.NewDefaultBackOffConfig(),
 		QueueConfig: exporterhelper.NewDefaultQueueSettings(),
+		Encoding:    EncodingProto,
 		ClientConfig: confighttp.ClientConfig{
 			Endpoint: "",
 			Timeout:  30 * time.Second,

exporter/otlphttpexporter/factory_test.go

@@ -35,6 +35,7 @@ func TestCreateDefaultConfig(t *testing.T) {
 	assert.Equal(t, ocfg.RetryConfig.InitialInterval, 5*time.Second, "default retry InitialInterval")
 	assert.Equal(t, ocfg.RetryConfig.MaxInterval, 30*time.Second, "default retry MaxInterval")
 	assert.Equal(t, ocfg.QueueConfig.Enabled, true, "default sending queue is enabled")
+	assert.Equal(t, ocfg.Encoding, EncodingProto)
 	assert.Equal(t, ocfg.Compression, configcompression.TypeGzip)
 }
 
@@ -154,6 +155,20 @@ func TestCreateTracesExporter(t *testing.T) {
 				},
 			},
 		},
+		{
+			name: "ProtoEncoding",
+			config: &Config{
+				Encoding:     EncodingProto,
+				ClientConfig: confighttp.ClientConfig{Endpoint: endpoint},
+			},
+		},
+		{
+			name: "JSONEncoding",
+			config: &Config{
+				Encoding:     EncodingJSON,
+				ClientConfig: confighttp.ClientConfig{Endpoint: endpoint},
+			},
+		},
 	}
 
 	for _, tt := range tests {

exporter/otlphttpexporter/otlp.go

@@ -48,6 +48,7 @@ const (
 	headerRetryAfter         = "Retry-After"
 	maxHTTPResponseReadBytes = 64 * 1024
 
+	jsonContentType     = "application/json"
 	protobufContentType = "application/x-protobuf"
 )
 
@@ -87,7 +88,18 @@ func (e *baseExporter) start(_ context.Context, host component.Host) error {
 
 func (e *baseExporter) pushTraces(ctx context.Context, td ptrace.Traces) error {
 	tr := ptraceotlp.NewExportRequestFromTraces(td)
-	request, err := tr.MarshalProto()
+
+	var err error
+	var request []byte
+	switch e.config.Encoding {
+	case EncodingJSON:
+		request, err = tr.MarshalJSON()
+	case EncodingProto:
+		request, err = tr.MarshalProto()
+	default:
+		err = fmt.Errorf("invalid encoding: %s", e.config.Encoding)
+	}
+
 	if err != nil {
 		return consumererror.NewPermanent(err)
 	}
@@ -97,7 +109,18 @@ func (e *baseExporter) pushTraces(ctx context.Context, td ptrace.Traces) error {
 
 func (e *baseExporter) pushMetrics(ctx context.Context, md pmetric.Metrics) error {
 	tr := pmetricotlp.NewExportRequestFromMetrics(md)
-	request, err := tr.MarshalProto()
+
+	var err error
+	var request []byte
+	switch e.config.Encoding {
+	case EncodingJSON:
+		request, err = tr.MarshalJSON()
+	case EncodingProto:
+		request, err = tr.MarshalProto()
+	default:
+		err = fmt.Errorf("invalid encoding: %s", e.config.Encoding)
+	}
+
 	if err != nil {
 		return consumererror.NewPermanent(err)
 	}
@@ -106,7 +129,18 @@ func (e *baseExporter) pushMetrics(ctx context.Context, md pmetric.Metrics) erro
 
 func (e *baseExporter) pushLogs(ctx context.Context, ld plog.Logs) error {
 	tr := plogotlp.NewExportRequestFromLogs(ld)
-	request, err := tr.MarshalProto()
+
+	var err error
+	var request []byte
+	switch e.config.Encoding {
+	case EncodingJSON:
+		request, err = tr.MarshalJSON()
+	case EncodingProto:
+		request, err = tr.MarshalProto()
+	default:
+		err = fmt.Errorf("invalid encoding: %s", e.config.Encoding)
+	}
+
 	if err != nil {
 		return consumererror.NewPermanent(err)
 	}
@@ -120,7 +154,16 @@ func (e *baseExporter) export(ctx context.Context, url string, request []byte, p
 	if err != nil {
 		return consumererror.NewPermanent(err)
 	}
-	req.Header.Set("Content-Type", protobufContentType)
+
+	switch e.config.Encoding {
+	case EncodingJSON:
+		req.Header.Set("Content-Type", jsonContentType)
+	case EncodingProto:
+		req.Header.Set("Content-Type", protobufContentType)
+	default:
+		return fmt.Errorf("invalid encoding: %s", e.config.Encoding)
+	}
+
 	req.Header.Set("User-Agent", e.userAgent)
 
 	resp, err := e.client.Do(req)
@@ -231,7 +274,6 @@ func readResponseStatus(resp *http.Response) *status.Status {
 		// "Response body for all HTTP 4xx and HTTP 5xx responses MUST be a
 		// Protobuf-encoded Status message that describes the problem."
 		respBytes, err := readResponseBody(resp)
-
 		if err != nil {
 			return nil
 		}
@@ -249,7 +291,6 @@ func readResponseStatus(resp *http.Response) *status.Status {
 
 func handlePartialSuccessResponse(resp *http.Response, partialSuccessHandler partialSuccessHandler) error {
 	bodyBytes, err := readResponseBody(resp)
-
 	if err != nil {
 		return err
 	}
@@ -260,14 +301,22 @@ func handlePartialSuccessResponse(resp *http.Response, partialSuccessHandler par
 type partialSuccessHandler func(bytes []byte, contentType string) error
 
 func (e *baseExporter) tracesPartialSuccessHandler(protoBytes []byte, contentType string) error {
-	if contentType != protobufContentType {
-		return nil
-	}
 	exportResponse := ptraceotlp.NewExportResponse()
-	err := exportResponse.UnmarshalProto(protoBytes)
-	if err != nil {
-		return fmt.Errorf("error parsing protobuf response: %w", err)
+	switch contentType {
+	case protobufContentType:
+		err := exportResponse.UnmarshalProto(protoBytes)
+		if err != nil {
+			return fmt.Errorf("error parsing protobuf response: %w", err)
+		}
+	case jsonContentType:
+		err := exportResponse.UnmarshalJSON(protoBytes)
+		if err != nil {
+			return fmt.Errorf("error parsing json response: %w", err)
+		}
+	default:
+		return nil
 	}
+
 	partialSuccess := exportResponse.PartialSuccess()
 	if !(partialSuccess.ErrorMessage() == "" && partialSuccess.RejectedSpans() == 0) {
 		e.logger.Warn("Partial success response",
@@ -279,14 +328,22 @@ func (e *baseExporter) tracesPartialSuccessHandler(protoBytes []byte, contentTyp
 }
 
 func (e *baseExporter) metricsPartialSuccessHandler(protoBytes []byte, contentType string) error {
-	if contentType != protobufContentType {
-		return nil
-	}
 	exportResponse := pmetricotlp.NewExportResponse()
-	err := exportResponse.UnmarshalProto(protoBytes)
-	if err != nil {
-		return fmt.Errorf("error parsing protobuf response: %w", err)
+	switch contentType {
+	case protobufContentType:
+		err := exportResponse.UnmarshalProto(protoBytes)
+		if err != nil {
+			return fmt.Errorf("error parsing protobuf response: %w", err)
+		}
+	case jsonContentType:
+		err := exportResponse.UnmarshalJSON(protoBytes)
+		if err != nil {
+			return fmt.Errorf("error parsing json response: %w", err)
+		}
+	default:
+		return nil
 	}
+
 	partialSuccess := exportResponse.PartialSuccess()
 	if !(partialSuccess.ErrorMessage() == "" && partialSuccess.RejectedDataPoints() == 0) {
 		e.logger.Warn("Partial success response",
@@ -298,14 +355,22 @@ func (e *baseExporter) metricsPartialSuccessHandler(protoBytes []byte, contentTy
 }
 
 func (e *baseExporter) logsPartialSuccessHandler(protoBytes []byte, contentType string) error {
-	if contentType != protobufContentType {
-		return nil
-	}
 	exportResponse := plogotlp.NewExportResponse()
-	err := exportResponse.UnmarshalProto(protoBytes)
-	if err != nil {
-		return fmt.Errorf("error parsing protobuf response: %w", err)
+	switch contentType {
+	case protobufContentType:
+		err := exportResponse.UnmarshalProto(protoBytes)
+		if err != nil {
+			return fmt.Errorf("error parsing protobuf response: %w", err)
+		}
+	case jsonContentType:
+		err := exportResponse.UnmarshalJSON(protoBytes)
+		if err != nil {
+			return fmt.Errorf("error parsing json response: %w", err)
+		}
+	default:
+		return nil
 	}
+
 	partialSuccess := exportResponse.PartialSuccess()
 	if !(partialSuccess.ErrorMessage() == "" && partialSuccess.RejectedLogRecords() == 0) {
 		e.logger.Warn("Partial success response",