Allow for custom non-http transports

client_configuration.go

@@ -359,6 +359,47 @@ func DefaultRetryPolicy(ctx context.Context, resp *http.Response, err error) (bo
 	return false, nil
 }
 
+// empty returns true if t is equivalent to an empty TLSConfiguration{} object.
+func (t *TLSConfiguration) empty() bool {
+	if t.ServerCertificate.FromFile != "" {
+		return false
+	}
+
+	if len(t.ServerCertificate.FromBytes) != 0 {
+		return false
+	}
+
+	if t.ServerCertificate.FromDirectory != "" {
+		return false
+	}
+
+	if t.ClientCertificate.FromFile != "" {
+		return false
+	}
+
+	if len(t.ClientCertificate.FromBytes) != 0 {
+		return false
+	}
+
+	if t.ClientCertificateKey.FromFile != "" {
+		return false
+	}
+
+	if len(t.ClientCertificateKey.FromBytes) != 0 {
+		return false
+	}
+
+	if t.ServerName != "" {
+		return false
+	}
+
+	if t.InsecureSkipVerify {
+		return false
+	}
+
+	return true
+}
+
 // applyTo applies the user-defined TLS configuration to the given client's
 // *tls.Config pointer; it is used to configure the internal http.Client
 func (from *TLSConfiguration) applyTo(to *tls.Config) error {

client_configuration_test.go

@@ -10,7 +10,7 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func Test_walkconfigurationfields(t *testing.T) {
+func Test_walkConfigurationFields(t *testing.T) {
 	var (
 		actual   = []string{}
 		expected = []string{
@@ -44,3 +44,47 @@ func Test_walkconfigurationfields(t *testing.T) {
 
 	require.Subset(t, actual, expected)
 }
+
+func Test_TLSConfiguration_empty(t *testing.T) {
+	cases := map[string]struct {
+		tls           TLSConfiguration
+		expectedEmpty bool
+	}{
+		"empty": {
+			tls:           TLSConfiguration{},
+			expectedEmpty: true,
+		},
+		"with-server-name": {
+			tls: TLSConfiguration{
+				ServerName: "my-server",
+			},
+			expectedEmpty: false,
+		},
+		"with-server-certificate-from-file": {
+			tls: TLSConfiguration{
+				ServerCertificate: ServerCertificateEntry{
+					FromFile: "./cert.pem",
+				},
+			},
+			expectedEmpty: false,
+		},
+		"with-server-certificate-from-bytes": {
+			tls: TLSConfiguration{
+				ServerCertificate: ServerCertificateEntry{
+					FromBytes: []byte{1, 1, 2, 3, 5},
+				},
+			},
+			expectedEmpty: false,
+		},
+	}
+
+	for name, tc := range cases {
+		t.Run(name, func(t *testing.T) {
+			if tc.expectedEmpty {
+				require.True(t, tc.tls.empty())
+			} else {
+				require.False(t, tc.tls.empty())
+			}
+		})
+	}
+}

generate/templates/client.handlebars

@@ -87,20 +87,33 @@ func newClient(configuration ClientConfiguration) (*Client, error) {
 	}
 	c.parsedBaseAddress = address
 
-	transport, ok := c.client.Transport.(*http.Transport);
-	if !ok {
-		return nil, fmt.Errorf("the configured base client's transport (%T) is not of type *http.Transport", c.client.Transport)
-	}
-
-	// Adjust the dial context for unix domain socket addresses.
 	if strings.HasPrefix(configuration.Address, "unix://") {
-		transport.DialContext = func(context.Context, string, string) (net.Conn, error) {
-			return net.Dial("unix", strings.TrimPrefix(configuration.Address, "unix://"))
+		// Adjust the dial context for unix domain socket addresses in the
+		// internal HTTP transport, if exists.
+		if httpTransport, ok := c.client.Transport.(*http.Transport); ok {
+			httpTransport.DialContext = func(context.Context, string, string) (net.Conn, error) {
+				return net.Dial("unix", strings.TrimPrefix(configuration.Address, "unix://"))
+			}
+		} else {
+			return nil, fmt.Errorf(
+				"the configured base client's transport (%T) is not of type *http.Transport and cannot be used with the unix:// address",
+				c.client.Transport,
+			)
 		}
 	}
 
-	if err := configuration.TLS.applyTo(transport.TLSClientConfig); err != nil {
-		return nil, err
+	if !configuration.TLS.empty() {
+		// Apply TLS configuration to the internal HTTP transport, if exists.
+		if httpTransport, ok := c.client.Transport.(*http.Transport); ok {
+			if err := configuration.TLS.applyTo(httpTransport.TLSClientConfig); err != nil {
+				return nil, err
+			}
+		} else {
+			return nil, fmt.Errorf(
+				"the configured base client's transport (%T) is not of type *http.Transport and cannot be used with TLS configuration",
+				c.client.Transport,
+			)
+		}
 	}
 
 {{#with apiInfo}}