Add proxy configuration options to the HTTP client

Author: ShocOne

httpclient/httpclient_client.go

@@ -13,6 +13,7 @@ import (
 	"time"
 
 	"github.com/deploymenttheory/go-api-http-client/logger"
+	"github.com/deploymenttheory/go-api-http-client/proxy"
 	"github.com/deploymenttheory/go-api-http-client/redirecthandler"
 	"go.uber.org/zap"
 )
@@ -38,6 +39,7 @@ type ClientConfig struct {
 	Auth          AuthConfig        // User can either supply these values manually or pass from LoadAuthConfig/Env vars
 	Environment   EnvironmentConfig // User can either supply these values manually or pass from LoadAuthConfig/Env vars
 	ClientOptions ClientOptions     // Optional configuration options for the HTTP Client
+	Proxy         ProxyConfig       // Proxy configuration options for the HTTP Client
 }
 
 // AuthConfig represents the structure to read authentication details from a JSON configuration file.
@@ -72,6 +74,13 @@ type ClientOptions struct {
 	CustomTimeout             time.Duration
 }
 
+type ProxyConfig struct {
+	ProxyURL       string `json:"ProxyURL,omitempty"`
+	ProxyUsername  string `json:"ProxyUsername,omitempty"`
+	ProxyPassword  string `json:"ProxyPassword,omitempty"`
+	ProxyAuthToken string `json:"ProxyAuthToken,omitempty"`
+}
+
 // ClientPerformanceMetrics captures various metrics related to the client's
 // interactions with the API, providing insights into its performance and behavior.
 type PerformanceMetrics struct {
@@ -126,6 +135,12 @@ func BuildClient(config ClientConfig) (*Client, error) {
 		log.Error("Failed to set up redirect handler", zap.Error(err))
 		return nil, err
 	}
+
+	// Conditionally Initialize the proxy if provided in the configuration
+	if err := proxy.InitializeProxy(httpClient, config.Proxy.ProxyURL, config.Proxy.ProxyUsername, config.Proxy.ProxyPassword, config.Proxy.ProxyAuthToken, log); err != nil {
+		return nil, err
+	}
+
 	// Create a new HTTP client with the provided configuration.
 	client := &Client{
 		APIHandler:         apiHandler,

proxy/proxy.go

@@ -0,0 +1,59 @@
+// proxy.go
+
+package proxy
+
+import (
+	"net/http"
+	"net/url"
+
+	"github.com/deploymenttheory/go-api-http-client/logger"
+	"go.uber.org/zap"
+)
+
+// InitializeProxy initializes the proxy configuration based on the provided options.
+// It supports proxy authentication using username/password or an authentication token (e.g., for SSO).
+func InitializeProxy(httpClient *http.Client, proxyURL, proxyUsername, proxyPassword, authToken string, log logger.Logger) error {
+	if proxyURL == "" {
+		return nil // No proxy configuration provided, nothing to do
+	}
+
+	parsedProxyURL, err := url.Parse(proxyURL)
+	if err != nil {
+		log.Error("Failed to parse proxy URL", zap.Error(err))
+		return err
+	}
+
+	// Initialize proxyAuth variable for username/password authentication
+	var proxyAuth *url.Userinfo
+	if proxyUsername != "" && proxyPassword != "" {
+		proxyAuth = url.UserPassword(proxyUsername, proxyPassword)
+	}
+
+	// Set up proxy with authentication if necessary
+	if proxyAuth != nil {
+		parsedProxyURL.User = proxyAuth
+		httpClient.Transport = &http.Transport{
+			Proxy: http.ProxyURL(parsedProxyURL),
+			ProxyConnectHeader: http.Header{
+				"Proxy-Authorization": []string{proxyAuth.String()},
+			},
+		}
+	} else if authToken != "" {
+		// SSO authentication
+		// Assuming authToken is passed in a configurable way (e.g., as a header)
+		httpClient.Transport = &http.Transport{
+			Proxy: http.ProxyURL(parsedProxyURL),
+			ProxyConnectHeader: http.Header{
+				"Authorization": []string{"Bearer " + authToken},
+			},
+		}
+	} else {
+		// Proxy without authentication
+		httpClient.Transport = &http.Transport{
+			Proxy: http.ProxyURL(parsedProxyURL),
+		}
+	}
+
+	log.Info("Proxy configured", zap.String("ProxyURL", proxyURL))
+	return nil
+}