add ID and Hostname in docker info

Signed-off-by: Victor Vieux <vieux@docker.com>

api/common.go

@@ -3,12 +3,15 @@ package api
 import (
 	"fmt"
 	"mime"
+	"os"
+	"path"
 	"strings"
 
 	log "github.com/Sirupsen/logrus"
 	"github.com/docker/docker/engine"
 	"github.com/docker/docker/pkg/parsers"
 	"github.com/docker/docker/pkg/version"
+	"github.com/docker/docker/vendor/src/github.com/docker/libtrust"
 )
 
 const (
@@ -47,3 +50,25 @@ func MatchesContentType(contentType, expectedType string) bool {
 	}
 	return err == nil && mimetype == expectedType
 }
+
+// LoadOrCreateTrustKey attempts to load the libtrust key at the given path,
+// otherwise generates a new one
+func LoadOrCreateTrustKey(trustKeyPath string) (libtrust.PrivateKey, error) {
+	err := os.MkdirAll(path.Dir(trustKeyPath), 0700)
+	if err != nil {
+		return nil, err
+	}
+	trustKey, err := libtrust.LoadKeyFile(trustKeyPath)
+	if err == libtrust.ErrKeyFileDoesNotExist {
+		trustKey, err = libtrust.GenerateECP256PrivateKey()
+		if err != nil {
+			return nil, fmt.Errorf("Error generating key: %s", err)
+		}
+		if err := libtrust.SaveKey(trustKeyPath, trustKey); err != nil {
+			return nil, fmt.Errorf("Error saving key file: %s", err)
+		}
+	} else if err != nil {
+		log.Fatalf("Error loading key file: %s", err)
+	}
+	return trustKey, nil
+}