feat(client): enhance HTTP client configuration with proxy support (#668)

* feat: enhance HTTP client configuration with proxy support

- Add `ProxyURL` field to `Config` struct with YAML tag
- Implement proxy URL parsing and setting in `getHTTPClient` method
- Add test case for `getHTTPClient` method with custom proxy URL setting
- Include `net/url` package in both `config.go` and `config_test.go` files

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

* docs: enhance README with Proxy and OAuth2 Docs

- Remove empty lines from README.md
- Add documentation for proxy configuration in client examples
- Include YAML examples for client using a proxy, custom DNS resolver, OAuth2, and identity-aware proxy configurations in README.md

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

* docs: add proxy client

Signed-off-by: appleboy <appleboy.tw@gmail.com>

* Update client/config.go

* Update README.md

* Update client/config_test.go

---------

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>
Signed-off-by: appleboy <appleboy.tw@gmail.com>
Co-authored-by: TwiN <twin@linux.com>

client/config.go

@@ -7,6 +7,7 @@ import (
 	"log"
 	"net"
 	"net/http"
+	"net/url"
 	"regexp"
 	"strconv"
 	"time"
@@ -42,6 +43,9 @@ func GetDefaultConfig() *Config {
 
 // Config is the configuration for clients
 type Config struct {
+	// ProxyURL is the URL of the proxy to use for the client
+	ProxyURL string `yaml:"proxy-url,omitempty"`
+
 	// Insecure determines whether to skip verifying the server's certificate chain and host name
 	Insecure bool `yaml:"insecure,omitempty"`
 
@@ -184,6 +188,14 @@ func (c *Config) getHTTPClient() *http.Client {
 				return nil
 			},
 		}
+		if c.ProxyURL != "" {
+			proxyURL, err := url.Parse(c.ProxyURL)
+			if err != nil {
+				log.Println("[client][getHTTPClient] THIS SHOULD NOT HAPPEN. Silently ignoring custom proxy due to error:", err.Error())
+			} else {
+				c.httpClient.Transport.(*http.Transport).Proxy = http.ProxyURL(proxyURL)
+			}
+		}
 		if c.HasCustomDNSResolver() {
 			dnsResolver, err := c.parseDNSResolver()
 			if err != nil {

client/config_test.go

@@ -2,6 +2,7 @@ package client
 
 import (
 	"net/http"
+	"net/url"
 	"testing"
 	"time"
 )
@@ -79,3 +80,29 @@ func TestConfig_ValidateAndSetDefaults_withCustomDNSResolver(t *testing.T) {
 		})
 	}
 }
+
+func TestConfig_getHTTPClient_withCustomProxyURL(t *testing.T) {
+	proxyURL := "http://proxy.example.com:8080"
+	cfg := &Config{
+		ProxyURL: proxyURL,
+	}
+	cfg.ValidateAndSetDefaults()
+	client := cfg.getHTTPClient()
+	transport := client.Transport.(*http.Transport)
+	if transport.Proxy == nil {
+		t.Errorf("expected Config.ProxyURL to set the HTTP client's proxy to %s", proxyURL)
+	}
+	req := &http.Request{
+		URL: &url.URL{
+			Scheme: "http",
+			Host:   "www.example.com",
+		},
+	}
+	expectProxyURL, err := transport.Proxy(req)
+	if err != nil {
+		t.Errorf("can't proxy the request %s", proxyURL)
+	}
+	if proxyURL != expectProxyURL.String() {
+		t.Errorf("expected Config.ProxyURL to set the HTTP client's proxy to %s", proxyURL)
+	}
+}