Load most common kernel modules on startup

cmd/hepto/service.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"net"
 	"os"
+	"os/exec"
 	"path"
 	"time"
 
@@ -51,6 +52,26 @@ var Start = &cobra.Command{
 				return err
 			}
 		}
+		// Load useful kernel modules for later operations
+		// This uses exec at the moment, which is undesireable in case hepto is used in a very
+		// limited environment
+		desiredModules := []string{
+			"nf_conntrack", // Required by most CNI
+			"ip6_tables",   // Required by kube-router, kube-proxy, Calico, and even Cilium
+			"ip6table_filter",
+			"ip6table_nat",
+			"ip6table_mangle",
+			"ip_tables", // Not used since hepto is IPv6 only, but required by most CNI
+			"iptable_filter",
+			"iptable_nat",
+			"iptable_mangle",
+		}
+		for _, mod := range desiredModules {
+			err := exec.Command("modprobe", "--", mod).Run()
+			if err != nil {
+				return err
+			}
+		}
 		return nil
 	},
 	RunE: func(cmd *cobra.Command, args []string) error {