libnetwork: don't register "libnetwork-setkey" re-exec on non-unix

It's a no-op on Windows and other non-Linux, non-FreeBSD platforms,
so there's no need to register the re-exec.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

libnetwork/sandbox_externalkey.go

@@ -1,12 +0,0 @@
-package libnetwork
-
-import "github.com/docker/docker/pkg/reexec"
-
-type setKeyData struct {
-	ContainerID string
-	Key         string
-}
-
-func init() {
-	reexec.Register("libnetwork-setkey", processSetKeyReexec)
-}

libnetwork/sandbox_externalkey_unix.go

@@ -13,6 +13,7 @@ import (
 	"path/filepath"
 
 	"github.com/docker/docker/libnetwork/types"
+	"github.com/docker/docker/pkg/reexec"
 	"github.com/docker/docker/pkg/stringid"
 	"github.com/opencontainers/runtime-spec/specs-go"
 	"github.com/sirupsen/logrus"
@@ -24,6 +25,16 @@ const (
 	success         = "success"
 )
 
+func init() {
+	// TODO(thaJeztah): should this actually be registered on FreeBSD, or only on Linux?
+	reexec.Register("libnetwork-setkey", processSetKeyReexec)
+}
+
+type setKeyData struct {
+	ContainerID string
+	Key         string
+}
+
 // processSetKeyReexec is a private function that must be called only on an reexec path
 // It expects 3 args { [0] = "libnetwork-setkey", [1] = <container-id>, [2] = <short-controller-id> }
 // It also expects specs.State as a json string in <stdin>
@@ -65,7 +76,8 @@ func setKey() error {
 func SetExternalKey(shortCtlrID string, containerID string, key string, execRoot string) error {
 	keyData := setKeyData{
 		ContainerID: containerID,
-		Key:         key}
+		Key:         key,
+	}
 
 	uds := filepath.Join(execRoot, execSubdir, shortCtlrID+".sock")
 	c, err := net.Dial("unix", uds)

libnetwork/sandbox_externalkey_unsupported.go

@@ -0,0 +1,11 @@
+//go:build !linux && !freebsd
+// +build !linux,!freebsd
+
+package libnetwork
+
+// no-op on non linux systems
+func (c *Controller) startExternalKeyListener() error {
+	return nil
+}
+
+func (c *Controller) stopExternalKeyListener() {}

libnetwork/sandbox_externalkey_windows.go

@@ -1,46 +0,0 @@
-//go:build windows
-// +build windows
-
-package libnetwork
-
-import (
-	"io"
-	"net"
-
-	"github.com/docker/docker/libnetwork/types"
-)
-
-// processSetKeyReexec is a private function that must be called only on an reexec path
-// It expects 3 args { [0] = "libnetwork-setkey", [1] = <container-id>, [2] = <controller-id> }
-// It also expects configs.HookState as a json string in <stdin>
-// Refer to https://github.com/opencontainers/runc/pull/160/ for more information
-func processSetKeyReexec() {
-}
-
-// SetExternalKey provides a convenient way to set an External key to a sandbox
-func SetExternalKey(controllerID string, containerID string, key string) error {
-	return types.NotImplementedErrorf("SetExternalKey isn't supported on non linux systems")
-}
-
-func sendKey(c net.Conn, data setKeyData) error {
-	return types.NotImplementedErrorf("sendKey isn't supported on non linux systems")
-}
-
-func processReturn(r io.Reader) error {
-	return types.NotImplementedErrorf("processReturn isn't supported on non linux systems")
-}
-
-// no-op on non linux systems
-func (c *Controller) startExternalKeyListener() error {
-	return nil
-}
-
-func (c *Controller) acceptClientConnections(sock string, l net.Listener) {
-}
-
-func (c *Controller) processExternalKey(conn net.Conn) error {
-	return types.NotImplementedErrorf("processExternalKey isn't supported on non linux systems")
-}
-
-func (c *Controller) stopExternalKeyListener() {
-}