feat: allow customization of proxy transport configuration

internal/config/proxy_server.go

@@ -1,13 +1,71 @@
 package config
 
+import "time"
+
 type ProxyServerConfig struct {
-	HTTP    HTTPConfig    `yaml:"http"`
-	Metrics MetricsConfig `yaml:"metrics"`
+	HTTP      HTTPConfig      `yaml:"http"`
+	Metrics   MetricsConfig   `yaml:"metrics"`
+	Transport TransportConfig `yaml:"transport"`
+	Dial      DialConfig      `yaml:"dial"`
+}
+
+// See https://pkg.go.dev/net/http#Transport
+type TransportConfig struct {
+	ForceAttemptHTTP2      InterpolatedBool      `yaml:"forceAttemptHTTP2"`
+	MaxIdleConns           InterpolatedInt       `yaml:"maxIdleConns"`
+	MaxIdleConnsPerHost    InterpolatedInt       `yaml:"maxIdleConnsPerHost"`
+	MaxConnsPerHost        InterpolatedInt       `yaml:"maxConnsPerHost"`
+	IdleConnTimeout        *InterpolatedDuration `yaml:"idleConnTimeout"`
+	TLSHandshakeTimeout    *InterpolatedDuration `yaml:"tlsHandshakeTimeout"`
+	ExpectContinueTimeout  *InterpolatedDuration `yaml:"expectContinueTimeout"`
+	DisableKeepAlives      InterpolatedBool      `yaml:"disableKeepAlives"`
+	DisableCompression     InterpolatedBool      `yaml:"disableCompression"`
+	ResponseHeaderTimeout  *InterpolatedDuration `yaml:"responseHeaderTimeout"`
+	WriteBufferSize        InterpolatedInt       `yaml:"writeBufferSize"`
+	ReadBufferSize         InterpolatedInt       `yaml:"readBufferSize"`
+	MaxResponseHeaderBytes InterpolatedInt       `yaml:"maxResponseHeaderBytes"`
 }
 
 func NewDefaultProxyServerConfig() ProxyServerConfig {
 	return ProxyServerConfig{
-		HTTP:    NewHTTPConfig("0.0.0.0", 8080),
-		Metrics: NewDefaultMetricsConfig(),
+		HTTP:      NewHTTPConfig("0.0.0.0", 8080),
+		Metrics:   NewDefaultMetricsConfig(),
+		Transport: NewDefaultTransportConfig(),
+		Dial:      NewDefaultDialConfig(),
+	}
+}
+
+// See https://pkg.go.dev/net#Dialer
+type DialConfig struct {
+	Timeout       *InterpolatedDuration `yaml:"timeout"`
+	KeepAlive     *InterpolatedDuration `yaml:"keepAlive"`
+	FallbackDelay *InterpolatedDuration `yaml:"fallbackDelay"`
+	DualStack     InterpolatedBool      `yaml:"dualStack"`
+}
+
+func NewDefaultDialConfig() DialConfig {
+	return DialConfig{
+		Timeout:       NewInterpolatedDuration(30 * time.Second),
+		KeepAlive:     NewInterpolatedDuration(30 * time.Second),
+		FallbackDelay: NewInterpolatedDuration(300 * time.Millisecond),
+		DualStack:     true,
+	}
+}
+
+func NewDefaultTransportConfig() TransportConfig {
+	return TransportConfig{
+		ForceAttemptHTTP2:      true,
+		MaxIdleConns:           100,
+		MaxIdleConnsPerHost:    100,
+		MaxConnsPerHost:        100,
+		IdleConnTimeout:        NewInterpolatedDuration(90 * time.Second),
+		TLSHandshakeTimeout:    NewInterpolatedDuration(10 * time.Second),
+		ExpectContinueTimeout:  NewInterpolatedDuration(1 * time.Second),
+		ResponseHeaderTimeout:  NewInterpolatedDuration(10 * time.Second),
+		DisableCompression:     false,
+		DisableKeepAlives:      false,
+		ReadBufferSize:         4096,
+		WriteBufferSize:        4096,
+		MaxResponseHeaderBytes: 0,
 	}
 }