From 21afa1a9759ce963cc4f2bfc1dee5288c57781e8 Mon Sep 17 00:00:00 2001
From: Samuel Ortiz <sameo@linux.intel.com>
Date: Thu, 23 Mar 2017 12:59:26 +0100
Subject: [PATCH] server: Fix the OCI process arguments build routine

We need to support a 2x2 matrix of use cases with both
kubelet giving us (command, args) slices and the OCI
image config file giving us (ENTRYPOINT, CMD) slices.

Here we always prioritize the kubelet information over
the OCI image one, and use the latter when the former
is incomplete.

Not that this routine will be slightly simpler when
issue #395 is fixed.

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
---
 server/container_create.go | 77 +++++++++++++++++++++++++++-----------
 1 file changed, 55 insertions(+), 22 deletions(-)

diff --git a/server/container_create.go b/server/container_create.go
index 0a051f0b..caa95591 100644
--- a/server/container_create.go
+++ b/server/container_create.go
@@ -60,6 +60,7 @@ func addOciBindMounts(sb *sandbox, containerConfig *pb.ContainerConfig, specgen
 // buildOCIProcessArgs build an OCI compatible process arguments slice.
 func buildOCIProcessArgs(containerKubeConfig *pb.ContainerConfig, imageOCIConfig *v1.Image) ([]string, error) {
 	processArgs := []string{}
+	var processEntryPoint, processCmd []string
 
 	kubeCommands := containerKubeConfig.Command
 	kubeArgs := containerKubeConfig.Args
@@ -86,34 +87,66 @@ func buildOCIProcessArgs(containerKubeConfig *pb.ContainerConfig, imageOCIConfig
 
 	// We got an OCI Image configuration.
 	// We will only use it if the kubelet information is incomplete.
-	if kubeCommands == nil {
-		if imageOCIConfig != nil && imageOCIConfig.Config.Entrypoint != nil {
-			processArgs = append(processArgs, imageOCIConfig.Config.Entrypoint...)
-		}
+
+	// First we set the process entry point.
+	if kubeCommands != nil {
+		// The kubelet command slice is prioritized.
+		processEntryPoint = kubeCommands
 	} else {
-		processArgs = append(processArgs, kubeCommands...)
+		// Here the kubelet command slice is empty.
+		if imageOCIConfig != nil {
+			// If the OCI image config has an ENTRYPOINT we
+			// use it as our process command.
+			// Otherwise we use the CMD slice if it's not
+			// empty.
+			if imageOCIConfig.Config.Entrypoint != nil {
+				processEntryPoint = imageOCIConfig.Config.Entrypoint
+			} else if imageOCIConfig.Config.Cmd != nil {
+				processEntryPoint = imageOCIConfig.Config.Cmd
+			}
+		} else {
+			// We neither have a kubelet command not an image OCI config.
+			// Missing an image OCI config will no longer be supported after
+			// https://github.com/kubernetes-incubator/cri-o/issues/395 is fixed.
+			processEntryPoint = []string{"/bin/sh", "-c"}
+		}
 	}
 
-	if kubeArgs == nil {
-		// Our kubelet command arguments slice is empty.
-		// We will use the OCI Image configuration only if we already
-		// have found a process command, i.e. if processArgs is no
-		// longer empty. No doing so will have us create a process
-		// arguments slice starting with the OCI Image command arguments
-		// as the entry point.
-		if processArgs != nil &&
-			imageOCIConfig != nil &&
-			imageOCIConfig.Config.Entrypoint != nil && imageOCIConfig.Config.Cmd != nil {
-			processArgs = append(processArgs, imageOCIConfig.Config.Cmd...)
-		}
+	// Then we build the process command arguments
+	if kubeArgs != nil {
+		// The kubelet command arguments slice is prioritized.
+		processCmd = kubeArgs
 	} else {
-		processArgs = append(processArgs, kubeArgs...)
+		if kubeCommands != nil {
+			// kubelet gave us a command slice but explicitely
+			// left the arguments slice empty. We should keep
+			// it that way.
+			processCmd = []string{}
+		} else {
+			// Here kubelet kept both the command and arguments
+			// slices empty. We should try building the process
+			// arguments slice from the OCI image config.
+			// If the OCI image config has an ENTRYPOINT slice,
+			// we use the CMD slice as the process arguments.
+			// Otherwise, we already picked CMD as our process
+			// command and we must not add the CMD slice twice.
+			if imageOCIConfig != nil {
+				if imageOCIConfig.Config.Entrypoint != nil {
+					processCmd = imageOCIConfig.Config.Cmd
+				} else {
+					processCmd = []string{}
+				}
+			} else {
+				// Missing an image OCI config will no longer
+				// be supported after https://github.com/kubernetes-incubator/cri-o/issues/395
+				// is fixed.
+				processCmd = []string{}
+			}
+		}
 	}
 
-	if processArgs == nil {
-		// Use a reasonable default if everything failed.
-		processArgs = []string{"/bin/sh"}
-	}
+	processArgs = append(processArgs, processEntryPoint...)
+	processArgs = append(processArgs, processCmd...)
 
 	logrus.Debugf("OCI process args %v", processArgs)