add proxy support to the HTTP client built by library

core/util/httputil/http_client_builder.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"net"
 	"net/http"
+	"net/url"
 	"time"
 
 	"github.com/pkg/errors"
@@ -16,6 +17,14 @@ import (
 	"github.com/retailcrm/mg-transport-core/v2/core/logger"
 )
 
+const (
+	defaultDialerTimeout         = 30 * time.Second
+	defaultIdleConnTimeout       = 90 * time.Second
+	defaultTLSHandshakeTimeout   = 10 * time.Second
+	defaultExpectContinueTimeout = 1 * time.Second
+	defaultMaxIdleConns          = 100
+)
+
 // DefaultClient stores original http.DefaultClient.
 var DefaultClient = http.DefaultClient
 
@@ -24,6 +33,7 @@ var DefaultTransport = http.DefaultTransport
 
 // HTTPClientBuilder builds http client with mocks (if necessary) and timeout.
 // Example:
+//
 //	// Build HTTP client with timeout = 10 sec, without SSL certificates verification and with mocked google.com
 //	client, err := NewHTTPClientBuilder().
 //		SetTimeout(10).
@@ -66,9 +76,20 @@ func NewHTTPClientBuilder() *HTTPClientBuilder {
 	return &HTTPClientBuilder{
 		built:      false,
 		httpClient: &http.Client{},
-		httpTransport: &http.Transport{},
+		httpTransport: &http.Transport{
+			Proxy: http.ProxyFromEnvironment,
+			DialContext: (&net.Dialer{
+				Timeout:   defaultDialerTimeout,
+				KeepAlive: defaultDialerTimeout,
+			}).DialContext,
+			ForceAttemptHTTP2:     true,
+			MaxIdleConns:          defaultMaxIdleConns,
+			IdleConnTimeout:       defaultIdleConnTimeout,
+			TLSHandshakeTimeout:   defaultTLSHandshakeTimeout,
+			ExpectContinueTimeout: defaultExpectContinueTimeout,
+		},
 		tlsVersion:    tls.VersionTLS12,
-		timeout:       30 * time.Second,
+		timeout:       defaultDialerTimeout,
 		mockAddress:   "",
 		mockedDomains: []string{},
 		logging:       false,
@@ -147,6 +168,11 @@ func (b *HTTPClientBuilder) SetLogging(flag bool) *HTTPClientBuilder {
 	return b
 }
 
+func (b *HTTPClientBuilder) SetProxy(proxy func(*http.Request) (*url.URL, error)) *HTTPClientBuilder {
+	b.httpTransport.Proxy = proxy
+	return b
+}
+
 // FromConfig fulfills mock configuration from HTTPClientConfig.
 func (b *HTTPClientBuilder) FromConfig(config *config.HTTPClientConfig) *HTTPClientBuilder {
 	if config == nil {
@@ -212,6 +238,7 @@ func (b *HTTPClientBuilder) buildMocks() error {
 			b.logf(" - %s\n", domain)
 		}
 
+		b.httpTransport.Proxy = nil
 		b.httpTransport.DialContext = func(ctx context.Context, network, addr string) (conn net.Conn, e error) {
 			var (
 				host string

core/util/httputil/http_client_builder_test.go

@@ -92,6 +92,13 @@ func (t *HTTPClientBuilderTest) Test_SetCertPool() {
 	assert.Equal(t.T(), pool, t.builder.httpTransport.TLSClientConfig.RootCAs)
 }
 
+func (t *HTTPClientBuilderTest) Test_SetProxy() {
+	t.builder.SetProxy(nil)
+	assert.Nil(t.T(), t.builder.httpTransport.Proxy)
+	t.builder.SetProxy(http.ProxyFromEnvironment)
+	assert.NotNil(t.T(), t.builder.httpTransport.Proxy)
+}
+
 func (t *HTTPClientBuilderTest) Test_FromConfigNil() {
 	defer func() {
 		assert.Nil(t.T(), recover())
@@ -161,6 +168,7 @@ func (t *HTTPClientBuilderTest) Test_Build() {
 
 	assert.NoError(t.T(), err)
 	assert.NotNil(t.T(), client)
+	assert.Nil(t.T(), client.Transport.(*http.Transport).Proxy)
 	assert.Equal(t.T(), client, http.DefaultClient)
 	assert.Equal(t.T(), timeout*time.Second, client.Timeout)
 	assert.Equal(t.T(), pool, client.Transport.(*http.Transport).TLSClientConfig.RootCAs)
@@ -290,6 +298,7 @@ uf/TQPpjrGW5nxOf94qn6FzV2WSype9BcM5MD7z7rk202Fs7Zqc=
 		SetSSLVerification(false).
 		Build()
 	require.NoError(t.T(), err, "cannot build client")
+	assert.Nil(t.T(), client.Transport.(*http.Transport).Proxy)
 
 	resp, err := client.Get(mockProto + mockDomainAddr)
 	if err != nil && strings.Contains(err.Error(), "connection refused") {
@@ -314,6 +323,7 @@ func (t *HTTPClientBuilderTest) Test_UseTLS10() {
 	t.Require().NotNil(client.Transport)
 	t.Require().NotNil(client.Transport.(*http.Transport).TLSClientConfig)
 	t.Assert().Equal(uint16(tls.VersionTLS10), client.Transport.(*http.Transport).TLSClientConfig.MinVersion)
+	t.Assert().NotNil(client.Transport.(*http.Transport).Proxy)
 }
 
 // taken from https://stackoverflow.com/questions/23558425/how-do-i-get-the-local-ip-address-in-go