Override Process.Args regardless of the existing value

Previously firecracker-containerd keeps
/etc/containerd/firecracker-runc-config.json's Process.Args as is
if the value exists.

However passing VM ID (39e0475) doesn't work when it uses the exising
fixed value.

This change removes this confusing behavior and always overrides
Process.Args.

Signed-off-by: Kazuyoshi Kato <[email protected]>

Author: kzys

runtime/runc_jailer.go

@@ -258,7 +258,7 @@ func (j *runcJailer) BuildJailedRootHandler(cfg *config.Config, machineConfig *f
 			j.logger.Debugf("Writing %q for runc", rootPathToConfig)
 			// we pass m.Cfg as opposed to machineConfig as we want the populated
 			// config defaults when calling NewMachine
-			if err := j.overwriteConfig(cfg, &m.Cfg, filepath.Base(m.Cfg.SocketPath), rootPathToConfig); err != nil {
+			if err := j.overwriteConfig(&m.Cfg, filepath.Base(m.Cfg.SocketPath), rootPathToConfig); err != nil {
 				return errors.Wrap(err, "failed to overwrite config.json")
 			}
 
@@ -478,7 +478,7 @@ func (j *runcJailer) jailerCommand(containerName string, isDebug bool) *exec.Cmd
 }
 
 // overwriteConfig will set the proper default values if a field had not been set.
-func (j *runcJailer) overwriteConfig(cfg *config.Config, machineConfig *firecracker.Config, socketPath, configPath string) error {
+func (j *runcJailer) overwriteConfig(machineConfig *firecracker.Config, socketPath, configPath string) error {
 	spec := j.configSpec
 	if spec.Process.User.UID != 0 ||
 		spec.Process.User.GID != 0 {
@@ -489,7 +489,7 @@ func (j *runcJailer) overwriteConfig(cfg *config.Config, machineConfig *firecrac
 		)
 	}
 
-	spec = j.setDefaultConfigValues(cfg, socketPath, spec)
+	spec = j.setDefaultConfigValues(socketPath, spec)
 	spec.Root.Path = rootfsFolder
 	spec.Root.Readonly = false
 	spec.Process.User.UID = j.Config.UID
@@ -537,24 +537,21 @@ func (j runcJailer) CgroupPath() string {
 	return filepath.Join(basePath, j.vmID)
 }
 
-// setDefaultConfigValues will process the spec file provided and allow any
-// empty/zero values to be replaced with default values.
-func (j *runcJailer) setDefaultConfigValues(cfg *config.Config, socketPath string, spec specs.Spec) specs.Spec {
+// setDefaultConfigValues will override the spec to start Firecracker inside.
+func (j *runcJailer) setDefaultConfigValues(socketPath string, spec specs.Spec) specs.Spec {
 	if spec.Process == nil {
 		spec.Process = &specs.Process{}
 	}
 
-	if spec.Process.Args == nil {
-		cmd := firecracker.VMCommandBuilder{}.
-			WithBin("/" + firecrackerFileName).
-			WithSocketPath(socketPath).
-			WithArgs([]string{"--id", j.vmID}).
-			// Don't need to pass in an actual context here as we are only building
-			// the command arguments and not actually building a command
-			Build(context.Background())
+	cmd := firecracker.VMCommandBuilder{}.
+		WithBin("/" + firecrackerFileName).
+		WithSocketPath(socketPath).
+		WithArgs([]string{"--id", j.vmID}).
+		// Don't need to pass in an actual context here as we are only building
+		// the command arguments and not actually building a command
+		Build(context.Background())
 
-		spec.Process.Args = cmd.Args
-	}
+	spec.Process.Args = cmd.Args
 
 	cgroupPath := j.CgroupPath()
 	j.logger.WithField("CgroupPath", cgroupPath).Debug("using cgroup path")