Allow config sources to be specified for containerd

By default container extracts the current config by running
the `containerd config dump` command and if that fails
we read the existing config file.

This change allows ordering of these sources to be defined as
we do for the nvidia-ctk runtime configure command.

Signed-off-by: Evan Lezar <[email protected]>

Author: elezar

tools/container/container.go

@@ -50,6 +50,8 @@ type Options struct {
 	SetAsDefault  bool
 	RestartMode   string
 	HostRootMount string
+
+	ConfigSources []string
 }
 
 // ParseArgs parses the command line arguments to the CLI

tools/container/runtime/containerd/containerd.go

@@ -169,12 +169,23 @@ func GetLowlevelRuntimePaths(o *container.Options, co *Options) ([]string, error
 }
 
 func getRuntimeConfig(o *container.Options, co *Options) (engine.Interface, error) {
+	var loaders []toml.Loader
+	for _, source := range o.ConfigSources {
+		switch source {
+		case "file":
+			loaders = append(loaders, toml.FromFile(o.Config))
+		case "command":
+			loaders = append(loaders, containerd.CommandLineSource(o.HostRootMount, o.ExecutablePath))
+		default:
+			// TODO: log a warning here.
+		}
+	}
+
 	return containerd.New(
 		containerd.WithPath(o.Config),
 		containerd.WithConfigSource(
 			toml.LoadFirst(
-				containerd.CommandLineSource(o.HostRootMount, o.ExecutablePath),
-				toml.FromFile(o.Config),
+				loaders...,
 			),
 		),
 		containerd.WithRuntimeType(co.runtimeType),

tools/container/runtime/runtime.go

@@ -103,6 +103,12 @@ func Flags(opts *Options) []cli.Flag {
 			EnvVars:     []string{"NVIDIA_RUNTIME_SET_AS_DEFAULT", "CONTAINERD_SET_AS_DEFAULT", "DOCKER_SET_AS_DEFAULT"},
 			Hidden:      true,
 		},
+		&cli.StringSliceFlag{
+			Name:        "config-source",
+			Usage:       "specify the config sources",
+			Destination: &opts.ConfigSources,
+			Sources:     cli.EnvVars("RUNTIME_CONFIG_SOURCES"),
+		},
 	}
 
 	flags = append(flags, containerd.Flags(&opts.containerdOptions)...)
@@ -137,6 +143,9 @@ func (opts *Options) Validate(c *cli.Context, runtime string, toolkitRoot string
 		if opts.RestartMode == runtimeSpecificDefault {
 			opts.RestartMode = containerd.DefaultRestartMode
 		}
+		if len(opts.ConfigSources) == 0 {
+			opts.ConfigSources = []string{"command", "file"}
+		}
 	case crio.Name:
 		if opts.Config == runtimeSpecificDefault {
 			opts.Config = crio.DefaultConfig