option to set custom http client in otel exporter

CHANGELOG.md

@@ -36,6 +36,7 @@ The next release will require at least [Go 1.22].
   It replaces the existing `Enabled` method that is removed from the `Processor` interface itself.
   It does not fall within the scope of the OpenTelemetry Go versioning and stability [policy](./VERSIONING.md) and it may be changed in backwards incompatible ways or removed in feature releases. (#5692)
 - Support [Go 1.23]. (#5720)
+- Option to configure `http.Client` in `go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp`. (#5752)
 
 ### Changed
 
@@ -1681,15 +1682,15 @@ with major version 0.
 
 - Adds `otlpgrpc.WithRetry`option for configuring the retry policy for transient errors on the otlp/gRPC exporter. (#1832)
   - The following status codes are defined as transient errors:
-      | gRPC Status Code | Description |
-      | ---------------- | ----------- |
-      | 1  | Cancelled |
-      | 4  | Deadline Exceeded |
-      | 8  | Resource Exhausted |
-      | 10 | Aborted |
-      | 10 | Out of Range |
-      | 14 | Unavailable |
-      | 15 | Data Loss |
+      | gRPC Status Code | Description        |
+      | ---------------- | ------------------ |
+      | 1                | Cancelled          |
+      | 4                | Deadline Exceeded  |
+      | 8                | Resource Exhausted |
+      | 10               | Aborted            |
+      | 10               | Out of Range       |
+      | 14               | Unavailable        |
+      | 15               | Data Loss          |
 - Added `Status` type to the `go.opentelemetry.io/otel/sdk/trace` package to represent the status of a span. (#1874)
 - Added `SpanStub` type and its associated functions to the `go.opentelemetry.io/otel/sdk/trace/tracetest` package.
   This type can be used as a testing replacement for the `SpanSnapshot` that was removed from the `go.opentelemetry.io/otel/sdk/trace` package. (#1873)

exporters/otlp/otlptrace/otlptracegrpc/internal/otlpconfig/options.go

@@ -52,7 +52,8 @@ type (
 		// gRPC configurations
 		GRPCCredentials credentials.TransportCredentials
 
-		Proxy HTTPTransportProxyFunc
+		Proxy  HTTPTransportProxyFunc
+		Client *http.Client
 	}
 
 	Config struct {
@@ -351,3 +352,10 @@ func WithProxy(pf HTTPTransportProxyFunc) GenericOption {
 		return cfg
 	})
 }
+
+func WithHTTPClient(c *http.Client) GenericOption {
+	return newGenericOption(func(cfg Config) Config {
+		cfg.Traces.Client = c
+		return cfg
+	})
+}

exporters/otlp/otlptrace/otlptracehttp/client.go

@@ -76,7 +76,9 @@ func NewClient(opts ...Option) otlptrace.Client {
 		Timeout:   cfg.Traces.Timeout,
 	}
 
-	if cfg.Traces.TLSCfg != nil || cfg.Traces.Proxy != nil {
+	if cfg.Traces.Client != nil {
+		httpClient = cfg.Traces.Client
+	} else if cfg.Traces.TLSCfg != nil || cfg.Traces.Proxy != nil {
 		clonedTransport := ourTransport.Clone()
 		httpClient.Transport = clonedTransport
 

exporters/otlp/otlptrace/otlptracehttp/client_test.go

@@ -43,6 +43,18 @@ var (
 	}
 )
 
+type rtWrapper struct {
+	base http.RoundTripper
+}
+
+func (rt rtWrapper) RoundTrip(req *http.Request) (*http.Response, error) {
+	for k, v := range customProxyHeader {
+		req.Header.Set(k, v)
+	}
+
+	return rt.base.RoundTrip(req)
+}
+
 func TestEndToEnd(t *testing.T) {
 	tests := []struct {
 		name            string
@@ -169,6 +181,17 @@ func TestEndToEnd(t *testing.T) {
 				ExpectedHeaders: customProxyHeader,
 			},
 		},
+		{
+			name: "with custom http client",
+			opts: []otlptracehttp.Option{
+				otlptracehttp.WithHTTPClient(&http.Client{
+					Transport: &rtWrapper{base: http.DefaultTransport},
+				}),
+			},
+			mcCfg: mockCollectorConfig{
+				ExpectedHeaders: customProxyHeader,
+			},
+		},
 	}
 
 	for _, tc := range tests {

exporters/otlp/otlptrace/otlptracehttp/internal/otlpconfig/options.go

@@ -52,7 +52,8 @@ type (
 		// gRPC configurations
 		GRPCCredentials credentials.TransportCredentials
 
-		Proxy HTTPTransportProxyFunc
+		Proxy  HTTPTransportProxyFunc
+		Client *http.Client
 	}
 
 	Config struct {
@@ -351,3 +352,10 @@ func WithProxy(pf HTTPTransportProxyFunc) GenericOption {
 		return cfg
 	})
 }
+
+func WithHTTPClient(c *http.Client) GenericOption {
+	return newGenericOption(func(cfg Config) Config {
+		cfg.Traces.Client = c
+		return cfg
+	})
+}

exporters/otlp/otlptrace/otlptracehttp/options.go

@@ -153,3 +153,11 @@ func WithRetry(rc RetryConfig) Option {
 func WithProxy(pf HTTPTransportProxyFunc) Option {
 	return wrappedOption{otlpconfig.WithProxy(otlpconfig.HTTPTransportProxyFunc(pf))}
 }
+
+// WithHTTPClient sets the HTTP client the exporter will use to send
+// traces to the collector. If this option is not used, the exporter will
+// create a new HTTP client. If the client is configured, WithProxy and WithTLSClientConfig
+// will have no effect.
+func WithHTTPClient(client *http.Client) Option {
+	return wrappedOption{otlpconfig.WithHTTPClient(client)}
+}

internal/shared/otlp/otlptrace/otlpconfig/options.go.tmpl

@@ -53,6 +53,7 @@ type (
 		GRPCCredentials credentials.TransportCredentials
 
 		Proxy HTTPTransportProxyFunc
+		Client *http.Client
 	}
 
 	Config struct {
@@ -351,3 +352,10 @@ func WithProxy(pf HTTPTransportProxyFunc) GenericOption {
 		return cfg
 	})
 }
+
+func WithHTTPClient(c *http.Client) GenericOption {
+	return newGenericOption(func(cfg Config) Config {
+		cfg.Traces.Client = c
+		return cfg
+	})
+}