Add server config for stream processors

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

services/server/config/config.go

@@ -56,9 +56,25 @@ type Config struct {
 	// ProxyPlugins configures plugins which are communicated to over GRPC
 	ProxyPlugins map[string]ProxyPlugin `toml:"proxy_plugins"`
 
+	StreamProcessors []StreamProcessor `toml:"stream_processors"`
+
 	md toml.MetaData
 }
 
+// StreamProcessor provides configuration for diff content processors
+type StreamProcessor struct {
+	// ID of the processor, also used to fetch the specific payload
+	ID string `toml:"id"`
+	// Accepts specific media-types
+	Accepts []string `toml:"accepts"`
+	// Returns the media-type
+	Returns string `toml:"returns"`
+	// Path or name of the binary
+	Path string `toml:"path"`
+	// Args to the binary
+	Args []string `toml:"args"`
+}
+
 // GetVersion returns the config file's version
 func (c *Config) GetVersion() int {
 	if c.Version == 0 {

services/server/server.go

@@ -35,6 +35,7 @@ import (
 	"github.com/containerd/containerd/content/local"
 	csproxy "github.com/containerd/containerd/content/proxy"
 	"github.com/containerd/containerd/defaults"
+	"github.com/containerd/containerd/diff"
 	"github.com/containerd/containerd/events/exchange"
 	"github.com/containerd/containerd/log"
 	"github.com/containerd/containerd/metadata"
@@ -80,6 +81,10 @@ func New(ctx context.Context, config *srvconfig.Config) (*Server, error) {
 	if err != nil {
 		return nil, err
 	}
+	for _, p := range config.StreamProcessors {
+		diff.RegisterProcessor(diff.BinaryHandler(p.ID, p.Returns, p.Accepts, p.Path, p.Args))
+	}
+
 	serverOpts := []grpc.ServerOption{
 		grpc.UnaryInterceptor(grpc_prometheus.UnaryServerInterceptor),
 		grpc.StreamInterceptor(grpc_prometheus.StreamServerInterceptor),