Add configurable plugin path

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

services/server/config/config.go

@@ -28,6 +28,8 @@ type Config struct {
 	Root string `toml:"root"`
 	// State is the path to a directory where containerd will store transient data
 	State string `toml:"state"`
+	// PluginDir is the directory for dynamic plugins to be stored
+	PluginDir string `toml:"plugin_dir"`
 	// GRPC configuration settings
 	GRPC GRPCConfig `toml:"grpc"`
 	// Debug and profiling settings

services/server/server.go

@@ -220,7 +220,11 @@ func (s *Server) Stop() {
 // of all plugins.
 func LoadPlugins(ctx context.Context, config *srvconfig.Config) ([]*plugin.Registration, error) {
 	// load all plugins into containerd
-	if err := plugin.Load(filepath.Join(config.Root, "plugins")); err != nil {
+	path := config.PluginDir
+	if path == "" {
+		path = filepath.Join(config.Root, "plugins")
+	}
+	if err := plugin.Load(path); err != nil {
 		return nil, err
 	}
 	// load additional plugins that don't automatically register themselves