Fixes #1858: Allow specifying a custom HTTP transport for the otlphttp driver

exporters/otlp/internal/otlpconfig/options.go

@@ -17,6 +17,7 @@ package otlpconfig // import "go.opentelemetry.io/otel/exporters/otlp/internal/o
 import (
 	"crypto/tls"
 	"fmt"
+	"net/http"
 	"time"
 
 	"google.golang.org/grpc"
@@ -64,6 +65,9 @@ type (
 		Timeout     time.Duration
 		URLPath     string
 
+		// http configurations
+		HTTPTransport http.RoundTripper
+
 		// gRPC configurations
 		GRPCCredentials credentials.TransportCredentials
 	}
@@ -89,16 +93,18 @@ type (
 func NewDefaultConfig() Config {
 	c := Config{
 		Traces: SignalConfig{
-			Endpoint:    fmt.Sprintf("%s:%d", otlp.DefaultCollectorHost, otlp.DefaultCollectorPort),
-			URLPath:     DefaultTracesPath,
-			Compression: otlp.NoCompression,
-			Timeout:     DefaultTimeout,
+			Endpoint:      fmt.Sprintf("%s:%d", otlp.DefaultCollectorHost, otlp.DefaultCollectorPort),
+			URLPath:       DefaultTracesPath,
+			Compression:   otlp.NoCompression,
+			Timeout:       DefaultTimeout,
+			HTTPTransport: http.DefaultTransport,
 		},
 		Metrics: SignalConfig{
-			Endpoint:    fmt.Sprintf("%s:%d", otlp.DefaultCollectorHost, otlp.DefaultCollectorPort),
-			URLPath:     DefaultMetricsPath,
-			Compression: otlp.NoCompression,
-			Timeout:     DefaultTimeout,
+			Endpoint:      fmt.Sprintf("%s:%d", otlp.DefaultCollectorHost, otlp.DefaultCollectorPort),
+			URLPath:       DefaultMetricsPath,
+			Compression:   otlp.NoCompression,
+			Timeout:       DefaultTimeout,
+			HTTPTransport: http.DefaultTransport,
 		},
 		MaxAttempts:   DefaultMaxAttempts,
 		Backoff:       DefaultBackoff,
@@ -364,3 +370,22 @@ func WithBackoff(duration time.Duration) GenericOption {
 		cfg.Backoff = duration
 	})
 }
+
+func WithMetricsHTTPTransport(transport http.RoundTripper) HTTPOption {
+	return NewHTTPOption(func(cfg *Config) {
+		cfg.Metrics.HTTPTransport = transport
+	})
+}
+
+func WithTracesHTTPTransport(transport http.RoundTripper) HTTPOption {
+	return NewHTTPOption(func(cfg *Config) {
+		cfg.Traces.HTTPTransport = transport
+	})
+}
+
+func WithHTTPTransport(transport http.RoundTripper) HTTPOption {
+	return NewHTTPOption(func(cfg *Config) {
+		cfg.Metrics.HTTPTransport = transport
+		cfg.Traces.HTTPTransport = transport
+	})
+}

exporters/otlp/internal/otlpconfig/options_test.go

@@ -18,6 +18,7 @@ import (
 	"crypto/tls"
 	"crypto/x509"
 	"errors"
+	"net/http"
 	"testing"
 	"time"
 
@@ -423,3 +424,56 @@ func TestConfigs(t *testing.T) {
 		})
 	}
 }
+
+func TestHTTPConfigs(t *testing.T) {
+	customTransport := http.DefaultTransport.(*http.Transport).Clone()
+	customTransport.MaxConnsPerHost = 42
+
+	tests := []struct {
+		name    string
+		opts    []HTTPOption
+		asserts func(t *testing.T, c *Config)
+	}{
+		// HTTP Transport Tests
+		{
+			name: "Test with custom traces transport",
+			opts: []HTTPOption{
+				WithTracesHTTPTransport(customTransport),
+			},
+			asserts: func(t *testing.T, c *Config) {
+				assert.Equal(t, customTransport, c.Traces.HTTPTransport)
+				assert.Equal(t, http.DefaultTransport, c.Metrics.HTTPTransport)
+			},
+		},
+		{
+			name: "Test with custom metrics transport",
+			opts: []HTTPOption{
+				WithMetricsHTTPTransport(customTransport),
+			},
+			asserts: func(t *testing.T, c *Config) {
+				assert.Equal(t, http.DefaultTransport, c.Traces.HTTPTransport)
+				assert.Equal(t, customTransport, c.Metrics.HTTPTransport)
+			},
+		},
+		{
+			name: "Test with custom transports",
+			opts: []HTTPOption{
+				WithHTTPTransport(customTransport),
+			},
+			asserts: func(t *testing.T, c *Config) {
+				assert.Equal(t, customTransport, c.Traces.HTTPTransport)
+				assert.Equal(t, customTransport, c.Metrics.HTTPTransport)
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			cfg := NewDefaultConfig()
+			for _, opt := range tt.opts {
+				opt.ApplyHTTPOption(&cfg)
+			}
+			tt.asserts(t, &cfg)
+		})
+	}
+}

exporters/otlp/otlphttp/driver.go

@@ -22,7 +22,6 @@ import (
 	"io"
 	"io/ioutil"
 	"math/rand"
-	"net"
 	"net/http"
 	"path"
 	"strings"
@@ -45,24 +44,6 @@ import (
 const contentTypeProto = "application/x-protobuf"
 const contentTypeJSON = "application/json"
 
-// Keep it in sync with golang's DefaultTransport from net/http! We
-// have our own copy to avoid handling a situation where the
-// DefaultTransport is overwritten with some different implementation
-// of http.RoundTripper or it's modified by other package.
-var ourTransport *http.Transport = &http.Transport{
-	Proxy: http.ProxyFromEnvironment,
-	DialContext: (&net.Dialer{
-		Timeout:   30 * time.Second,
-		KeepAlive: 30 * time.Second,
-		DualStack: true,
-	}).DialContext,
-	ForceAttemptHTTP2:     true,
-	MaxIdleConns:          100,
-	IdleConnTimeout:       90 * time.Second,
-	TLSHandshakeTimeout:   10 * time.Second,
-	ExpectContinueTimeout: 1 * time.Second,
-}
-
 type driver struct {
 	metricsDriver signalDriver
 	tracesDriver  signalDriver
@@ -115,23 +96,29 @@ func NewDriver(opts ...Option) otlp.ProtocolDriver {
 	}
 
 	metricsClient := &http.Client{
-		Transport: ourTransport,
+		Transport: cfg.Metrics.HTTPTransport,
 		Timeout:   cfg.Metrics.Timeout,
 	}
 	if cfg.Metrics.TLSCfg != nil {
-		transport := ourTransport.Clone()
-		transport.TLSClientConfig = cfg.Metrics.TLSCfg
-		metricsClient.Transport = transport
+		// only support TLS config when the HTTP transport is a *http.Transport
+		if tr, ok := metricsClient.Transport.(*http.Transport); ok {
+			transport := tr.Clone()
+			transport.TLSClientConfig = cfg.Metrics.TLSCfg
+			metricsClient.Transport = transport
+		}
 	}
 
 	tracesClient := &http.Client{
-		Transport: ourTransport,
+		Transport: cfg.Traces.HTTPTransport,
 		Timeout:   cfg.Traces.Timeout,
 	}
 	if cfg.Traces.TLSCfg != nil {
-		transport := ourTransport.Clone()
-		transport.TLSClientConfig = cfg.Traces.TLSCfg
-		tracesClient.Transport = transport
+		// only support TLS config when the HTTP transport is a *http.Transport
+		if tr, ok := tracesClient.Transport.(*http.Transport); ok {
+			transport := tr.Clone()
+			transport.TLSClientConfig = cfg.Traces.TLSCfg
+			tracesClient.Transport = transport
+		}
 	}
 
 	stopCh := make(chan struct{})

exporters/otlp/otlphttp/options.go

@@ -16,6 +16,7 @@ package otlphttp
 
 import (
 	"crypto/tls"
+	"net/http"
 	"time"
 
 	"go.opentelemetry.io/otel/exporters/otlp"
@@ -197,3 +198,27 @@ func WithTracesTimeout(duration time.Duration) Option {
 func WithMetricsTimeout(duration time.Duration) Option {
 	return otlpconfig.WithMetricsTimeout(duration)
 }
+
+// WithMetricsHTTPTransport can be used to customize the HTTP transport that is used to
+// handle the HTTP connection to the metrics server
+func WithMetricsHTTPTransport(transport http.RoundTripper) Option {
+	return otlpconfig.WithMetricsHTTPTransport(transport)
+}
+
+// WithTracesHTTPTransport can be used to customize the HTTP transport that is used to
+// handle the HTTP connection to the traces server
+//
+// Note that a client should not provide a otelhttp.Transport to this method, as it will
+// create spans for every outgoing request, causing never-ending trace data.
+func WithTracesHTTPTransport(transport http.RoundTripper) Option {
+	return otlpconfig.WithTracesHTTPTransport(transport)
+}
+
+// WithTracesHTTPTransport can be used to customize the HTTP transport that is used to
+// handle both the HTTP connection to the traces and the metrics server.
+//
+// Note that a client should not provide a otelhttp.Transport to this method, as it will
+// create spans for every outgoing request, causing never-ending trace data.
+func WithHTTPTransport(transport http.RoundTripper) Option {
+	return otlpconfig.WithHTTPTransport(transport)
+}