daemon: only create trust-key if DOCKER_ALLOW_SCHEMA1_PUSH_DONOTUSE is set

The libtrust trust-key is only used for pushing legacy image manifests;
pushing these images has been deprecated, and we only need to be able
to push them in our CI.

This patch disables generating the trust-key (and related paths) unless
the DOCKER_ALLOW_SCHEMA1_PUSH_DONOTUSE env-var is set (which we do in
our CI).

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

daemon/daemon.go

@@ -985,17 +985,6 @@ func NewDaemon(ctx context.Context, config *config.Config, pluginStore *plugin.S
 		logrus.WithError(err).Warnf("unable to migrate engine ID; a new engine ID will be generated")
 	}
 
-	trustKey, err := loadOrCreateTrustKey(config.TrustKeyPath)
-	if err != nil {
-		return nil, err
-	}
-
-	trustDir := filepath.Join(config.Root, "trust")
-
-	if err := system.MkdirAll(trustDir, 0700); err != nil {
-		return nil, err
-	}
-
 	// We have a single tag/reference store for the daemon globally. However, it's
 	// stored under the graphdriver. On host platforms which only support a single
 	// container OS, but multiple selectable graphdrivers, this means depending on which
@@ -1057,10 +1046,22 @@ func NewDaemon(ctx context.Context, config *config.Config, pluginStore *plugin.S
 		MaxDownloadAttempts:       *config.MaxDownloadAttempts,
 		ReferenceStore:            rs,
 		RegistryService:           registryService,
-		TrustKey:                  trustKey,
 		ContentNamespace:          config.ContainerdNamespace,
 	}
 
+	// This is a temporary environment variables used in CI to allow pushing
+	// manifest v2 schema 1 images to test-registries used for testing *pulling*
+	// these images.
+	if os.Getenv("DOCKER_ALLOW_SCHEMA1_PUSH_DONOTUSE") != "" {
+		imgSvcConfig.TrustKey, err = loadOrCreateTrustKey(config.TrustKeyPath)
+		if err != nil {
+			return nil, err
+		}
+		if err = system.MkdirAll(filepath.Join(config.Root, "trust"), 0700); err != nil {
+			return nil, err
+		}
+	}
+
 	// containerd is not currently supported with Windows.
 	// So sometimes d.containerdCli will be nil
 	// In that case we'll create a local content store... but otherwise we'll use containerd

integration-cli/docker_cli_daemon_test.go

@@ -559,6 +559,7 @@ func (s *DockerDaemonSuite) TestDaemonAllocatesListeningPort(c *testing.T) {
 func (s *DockerDaemonSuite) TestDaemonKeyGeneration(c *testing.T) {
 	// TODO: skip or update for Windows daemon
 	os.Remove("/etc/docker/key.json")
+	c.Setenv("DOCKER_ALLOW_SCHEMA1_PUSH_DONOTUSE", "1")
 	s.d.Start(c)
 	s.d.Stop(c)
 
@@ -1212,6 +1213,7 @@ func (s *DockerDaemonSuite) TestDaemonWithWrongkey(c *testing.T) {
 	}
 
 	os.Remove("/etc/docker/key.json")
+	c.Setenv("DOCKER_ALLOW_SCHEMA1_PUSH_DONOTUSE", "1")
 	s.d.Start(c)
 	s.d.Stop(c)