Do not keep alive http connection (#3878)

CHANGELOG.md

@@ -56,6 +56,7 @@ To learn more about active deprecations, we recommend checking [GitHub Discussio
 - **General:** Add explicit seccompProfile type to securityContext config ([#3561](https://github.com/kedacore/keda/issues/3561))
 - **General:** Add `Min` column to ScaledJob visualization ([#3689](https://github.com/kedacore/keda/issues/3689))
 - **General:** Add support to use pod identities for authentication in Azure Key Vault ([#3813](https://github.com/kedacore/keda/issues/3813)
+- **General:** Support disable keep http connection alive([#3874](https://github.com/kedacore/keda/issues/3874)
 - **General:** Improve the function used to normalize metric names ([#3789](https://github.com/kedacore/keda/issues/3789)
 - **Apache Kafka Scaler:** SASL/OAuthbearer Implementation ([#3681](https://github.com/kedacore/keda/issues/3681))
 - **Azure AD Pod Identity Authentication:** Improve error messages to emphasize problems around the integration with aad-pod-identity itself ([#3610](https://github.com/kedacore/keda/issues/3610))

pkg/util/env_resolver.go

@@ -26,3 +26,13 @@ func ResolveOsEnvDuration(envName string) (*time.Duration, error) {
 
 	return nil, nil
 }
+
+func ResolveOsEnvBool(envName string, defaultValue bool) (bool, error) {
+	valueStr, found := os.LookupEnv(envName)
+
+	if found && valueStr != "" {
+		return strconv.ParseBool(valueStr)
+	}
+
+	return defaultValue, nil
+}

pkg/util/http.go

@@ -22,6 +22,16 @@ import (
 	"time"
 )
 
+var disableKeepAlives bool
+
+func init() {
+	var err error
+	disableKeepAlives, err = ResolveOsEnvBool("KEDA_HTTP_DISABLE_KEEP_ALIVE", false)
+	if err != nil {
+		disableKeepAlives = false
+	}
+}
+
 // HTTPDoer is an interface that matches the Do method on
 // (net/http).Client. It should be used in function signatures
 // instead of raw *http.Clients wherever possible
@@ -37,13 +47,18 @@ func CreateHTTPClient(timeout time.Duration, unsafeSsl bool) *http.Client {
 	if timeout <= 0 {
 		timeout = 300 * time.Millisecond
 	}
+	transport := &http.Transport{
+		TLSClientConfig: &tls.Config{InsecureSkipVerify: unsafeSsl},
+		Proxy:           http.ProxyFromEnvironment,
+	}
+	if disableKeepAlives {
+		// disable keep http connection alive
+		transport.DisableKeepAlives = true
+		transport.IdleConnTimeout = 100 * time.Second
+	}
 	httpClient := &http.Client{
-		Timeout: timeout,
-		Transport: &http.Transport{
-			TLSClientConfig: &tls.Config{InsecureSkipVerify: unsafeSsl},
-			Proxy:           http.ProxyFromEnvironment,
-		},
+		Timeout:   timeout,
+		Transport: transport,
 	}
-
 	return httpClient
 }