config: add dns_lookup_family option to customize DNS IP resolution (#1436)

config/validate.go

@@ -0,0 +1,39 @@
+package config
+
+import (
+	"fmt"
+	"strings"
+
+	envoy_config_cluster_v3 "github.com/envoyproxy/go-control-plane/envoy/config/cluster/v3"
+)
+
+// DNSLookupFamily values.
+const (
+	DNSLookupFamilyAuto   = "AUTO"
+	DNSLookupFamilyV4Only = "V4_ONLY"
+	DNSLookupFamilyV6Only = "V6_ONLY"
+)
+
+// AllDNSLookupFamilies are all the available DNSLookupFamily values.
+var AllDNSLookupFamilies = []string{DNSLookupFamilyV6Only, DNSLookupFamilyV4Only, DNSLookupFamilyAuto}
+
+// ValidateDNSLookupFamily validates the value to confirm its one of the available DNS lookup families.
+func ValidateDNSLookupFamily(value string) error {
+	switch value {
+	case "", DNSLookupFamilyAuto, DNSLookupFamilyV4Only, DNSLookupFamilyV6Only:
+		return nil
+	}
+
+	return fmt.Errorf("unknown dns_lookup_family: %s, known families are: %s", value, strings.Join(AllDNSLookupFamilies, ", "))
+}
+
+// GetEnvoyDNSLookupFamily gets the envoy DNS lookup family.
+func GetEnvoyDNSLookupFamily(value string) envoy_config_cluster_v3.Cluster_DnsLookupFamily {
+	switch value {
+	case DNSLookupFamilyV4Only:
+		return envoy_config_cluster_v3.Cluster_V4_ONLY
+	case DNSLookupFamilyV6Only:
+		return envoy_config_cluster_v3.Cluster_V6_ONLY
+	}
+	return envoy_config_cluster_v3.Cluster_AUTO
+}