Move plugin client creation to the extension point

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
Upstream-commit: f51a96c0165fdcbbe11f62b66b582b7e202f211b
Component: engine

components/engine/pkg/plugins/plugins.go

@@ -31,6 +31,9 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
+// ProtocolSchemeHTTPV1 is the name of the protocol used for interacting with plugins using this package.
+const ProtocolSchemeHTTPV1 = "moby.plugins.http/v1"
+
 var (
 	// ErrNotImplements is returned if the plugin does not implement the requested driver.
 	ErrNotImplements = errors.New("Plugin does not implement the requested driver")
@@ -88,6 +91,11 @@ func (p *Plugin) Client() *Client {
 	return p.client
 }
 
+// Protocol returns the protocol name/version used for plugins in this package.
+func (p *Plugin) Protocol() string {
+	return ProtocolSchemeHTTPV1
+}
+
 // IsV1 returns true for V1 plugins and false otherwise.
 func (p *Plugin) IsV1() bool {
 	return true