Headers configuration

README.md

@@ -18,6 +18,7 @@ It's worth to mention that the extension is using the [OpenTelemetry Go SDK](htt
 
 * `K6_OTEL_EXPORT_INTERVAL` - configures the intervening time between metrics exports. Default is `10s`.
 * `K6_OTEL_EXPORTER_TYPE` - metric exporter type. Default is `grpc`.
+* `K6_OTEL_HEADERS` - headers in W3C Correlation-Context format without additional semi-colon delimited metadata (i.e. "k1=v1,k2=v2"). Passes the headers to the exporter.
 
 #### TLS configuration
 

pkg/opentelemetry/config.go

@@ -39,6 +39,9 @@ type Config struct {
 	// ExportInterval configures the intervening time between metrics exports
 	ExportInterval types.NullDuration `json:"exportInterval" envconfig:"K6_OTEL_EXPORT_INTERVAL"`
 
+	// Headers in W3C Correlation-Context format without additional semi-colon delimited metadata (i.e. "k1=v1,k2=v2")
+	Headers null.String `json:"headers" envconfig:"K6_OTEL_HEADERS"`
+
 	// TLSInsecureSkipVerify disables verification of the server's certificate chain
 	TLSInsecureSkipVerify null.Bool `json:"tlsInsecureSkipVerify" envconfig:"K6_OTEL_TLS_INSECURE_SKIP_VERIFY"`
 	// TLSCertificate is the path to the certificate file (rootCAs) to use for the exporter's TLS connection
@@ -179,6 +182,10 @@ func (cfg Config) Apply(v Config) Config {
 		cfg.TLSClientKey = v.TLSClientKey
 	}
 
+	if v.Headers.Valid {
+		cfg.Headers = v.Headers
+	}
+
 	return cfg
 }
 

pkg/opentelemetry/config_test.go

@@ -68,6 +68,7 @@ func TestConfig(t *testing.T) {
 				"K6_OTEL_TLS_CERTIFICATE":          "cert_path",
 				"K6_OTEL_TLS_CLIENT_CERTIFICATE":   "client_cert_path",
 				"K6_OTEL_TLS_CLIENT_KEY":           "client_key_path",
+				"K6_OTEL_HEADERS":                  "key1=value1,key2=value2",
 			},
 			expectedConfig: Config{
 				ServiceName:           null.StringFrom("foo"),
@@ -84,6 +85,7 @@ func TestConfig(t *testing.T) {
 				TLSCertificate:        null.StringFrom("cert_path"),
 				TLSClientCertificate:  null.StringFrom("client_cert_path"),
 				TLSClientKey:          null.StringFrom("client_key_path"),
+				Headers:               null.StringFrom("key1=value1,key2=value2"),
 			},
 		},
 
@@ -103,7 +105,8 @@ func TestConfig(t *testing.T) {
 					`"tlsInsecureSkipVerify":true,` +
 					`"tlsCertificate":"cert_path",` +
 					`"tlsClientCertificate":"client_cert_path",` +
-					`"tlsClientKey":"client_key_path"` +
+					`"tlsClientKey":"client_key_path",` +
+					`"headers":"key1=value1,key2=value2"` +
 					`}`,
 			),
 			expectedConfig: Config{
@@ -121,6 +124,7 @@ func TestConfig(t *testing.T) {
 				TLSCertificate:        null.StringFrom("cert_path"),
 				TLSClientCertificate:  null.StringFrom("client_cert_path"),
 				TLSClientKey:          null.StringFrom("client_key_path"),
+				Headers:               null.StringFrom("key1=value1,key2=value2"),
 			},
 		},
 

pkg/opentelemetry/exporter.go

@@ -4,6 +4,9 @@ import (
 	"context"
 	"crypto/tls"
 	"errors"
+	"fmt"
+	"net/url"
+	"strings"
 
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc"
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp"
@@ -27,20 +30,33 @@ func getExporter(cfg Config) (metric.Exporter, error) {
 		return nil, err
 	}
 
+	var headers map[string]string
+	if cfg.Headers.Valid {
+		headers, err = parseHeaders(cfg.Headers.String)
+		if err != nil {
+			return nil, fmt.Errorf("failed to parse headers: %w", err)
+		}
+	}
+
 	exporterType := cfg.ExporterType.String
 
 	if exporterType == grpcExporterType {
-		return buildGRPCExporter(ctx, cfg, tlsConfig)
+		return buildGRPCExporter(ctx, cfg, tlsConfig, headers)
 	}
 
 	if exporterType == httpExporterType {
-		return buildHTTPExporter(ctx, cfg, tlsConfig)
+		return buildHTTPExporter(ctx, cfg, tlsConfig, headers)
 	}
 
 	return nil, errors.New("unsupported exporter type " + exporterType + " specified")
 }
 
-func buildHTTPExporter(ctx context.Context, cfg Config, tlsConfig *tls.Config) (metric.Exporter, error) {
+func buildHTTPExporter(
+	ctx context.Context,
+	cfg Config,
+	tlsConfig *tls.Config,
+	headers map[string]string,
+) (metric.Exporter, error) {
 	opts := []otlpmetrichttp.Option{
 		otlpmetrichttp.WithEndpoint(cfg.HTTPExporterEndpoint.String),
 		otlpmetrichttp.WithURLPath(cfg.HTTPExporterURLPath.String),
@@ -50,14 +66,23 @@ func buildHTTPExporter(ctx context.Context, cfg Config, tlsConfig *tls.Config) (
 		opts = append(opts, otlpmetrichttp.WithInsecure())
 	}
 
+	if len(headers) > 0 {
+		opts = append(opts, otlpmetrichttp.WithHeaders(headers))
+	}
+
 	if tlsConfig != nil {
 		opts = append(opts, otlpmetrichttp.WithTLSClientConfig(tlsConfig))
 	}
 
 	return otlpmetrichttp.New(ctx, opts...)
 }
 
-func buildGRPCExporter(ctx context.Context, cfg Config, tlsConfig *tls.Config) (metric.Exporter, error) {
+func buildGRPCExporter(
+	ctx context.Context,
+	cfg Config,
+	tlsConfig *tls.Config,
+	headers map[string]string,
+) (metric.Exporter, error) {
 	opt := []otlpmetricgrpc.Option{
 		otlpmetricgrpc.WithEndpoint(cfg.GRPCExporterEndpoint.String),
 	}
@@ -66,9 +91,37 @@ func buildGRPCExporter(ctx context.Context, cfg Config, tlsConfig *tls.Config) (
 		opt = append(opt, otlpmetricgrpc.WithInsecure())
 	}
 
+	if len(headers) > 0 {
+		opt = append(opt, otlpmetricgrpc.WithHeaders(headers))
+	}
+
 	if tlsConfig != nil {
 		opt = append(opt, otlpmetricgrpc.WithTLSCredentials(credentials.NewTLS(tlsConfig)))
 	}
 
 	return otlpmetricgrpc.New(ctx, opt...)
 }
+
+func parseHeaders(raw string) (map[string]string, error) {
+	headers := make(map[string]string)
+	for _, header := range strings.Split(raw, ",") {
+		rawKey, rawValue, ok := strings.Cut(header, "=")
+		if !ok {
+			return nil, fmt.Errorf("invalid header %q, expected format key=value", header)
+		}
+
+		key, err := url.PathUnescape(rawKey)
+		if err != nil {
+			return nil, fmt.Errorf("failed to unescape header key %q: %w", rawKey, err)
+		}
+
+		value, err := url.PathUnescape(rawValue)
+		if err != nil {
+			return nil, fmt.Errorf("failed to unescape header value %q: %w", rawValue, err)
+		}
+
+		headers[key] = value
+	}
+
+	return headers, nil
+}