server/container_create: Simplify Kube/OCI process merge

Handling both the nil ociConfig check and kubeCommands length check on
the same line lets us drop one level of nesting.  And that initial
zero-length check makes the internal kubeCommands nil check redundant,
so we can drop that too.

Also adjust the buildOCIProcessArgs argument from a *v1.Image to
*v1.ImageConfig, because we don't need anything else from Image here.
This moves the nil Image check from inside buildOCIProcessArgs to the
calling function, but I think that's worth the tighter scoping.

Author: wking

server/container_create.go

@@ -376,7 +376,7 @@ func addDevices(sb *sandbox.Sandbox, containerConfig *pb.ContainerConfig, specge
 }
 
 // buildOCIProcessArgs build an OCI compatible process arguments slice.
-func buildOCIProcessArgs(containerKubeConfig *pb.ContainerConfig, imageOCIConfig *v1.Image) ([]string, error) {
+func buildOCIProcessArgs(containerKubeConfig *pb.ContainerConfig, ociConfig *v1.ImageConfig) ([]string, error) {
 	//# Start the nginx container using the default command, but use custom
 	//arguments (arg1 .. argN) for that command.
 	//kubectl run nginx --image=nginx -- <arg1> <arg2> ... <argN>
@@ -388,15 +388,10 @@ func buildOCIProcessArgs(containerKubeConfig *pb.ContainerConfig, imageOCIConfig
 	kubeArgs := containerKubeConfig.Args
 
 	// merge image config and kube config
-	// same as docker does today...
-	if imageOCIConfig != nil {
-		if len(kubeCommands) == 0 {
-			if len(kubeArgs) == 0 {
-				kubeArgs = imageOCIConfig.Config.Cmd
-			}
-			if kubeCommands == nil {
-				kubeCommands = imageOCIConfig.Config.Entrypoint
-			}
+	if ociConfig != nil && len(kubeCommands) == 0 {
+		kubeCommands = ociConfig.Entrypoint
+		if len(kubeArgs) == 0 {
+			kubeArgs = ociConfig.Cmd
 		}
 	}
 
@@ -1163,9 +1158,12 @@ func (s *Server) createSandboxContainer(ctx context.Context, containerID string,
 		return nil, err
 	}
 
-	processArgs, err := buildOCIProcessArgs(containerConfig, containerImageConfig)
-	if err != nil {
-		return nil, err
+	processArgs := []string{}
+	if containerImageConfig != nil {
+		processArgs, err := buildOCIProcessArgs(containerConfig, &containerImageConfig.Config)
+		if err != nil {
+			return nil, err
+		}
 	}
 	specgen.SetProcessArgs(processArgs)