Add NVCT_CONFIG_FILE_PATH envvar

This change adds support for explicitly specifying the path
to the config file through an environment variable.
The NVCT_CONFIG_FILE_PATH variable is used for both the nvidia-container-runtime
and nvidia-container-runtime-hook.

Signed-off-by: Evan Lezar <elezar@nvidia.com>

Author: elezar

cmd/nvidia-container-runtime-hook/main.go

@@ -174,6 +174,7 @@ func main() {
 			Name:        "config",
 			Destination: &a.configFile,
 			Usage:       "The path to the configuration file to use",
+			EnvVars:     []string{config.FilePathOverrideEnvVar},
 		},
 	}
 

internal/config/config.go

@@ -30,6 +30,8 @@ import (
 )
 
 const (
+	FilePathOverrideEnvVar = "NVCTK_CONFIG_FILE_PATH"
+
 	configOverride = "XDG_CONFIG_HOME"
 	configFilePath = "nvidia-container-runtime/config.toml"
 
@@ -71,6 +73,9 @@ type Config struct {
 
 // GetConfigFilePath returns the path to the config file for the configured system
 func GetConfigFilePath() string {
+	if configFilePathOverride := os.Getenv(FilePathOverrideEnvVar); configFilePathOverride != "" {
+		return configFilePathOverride
+	}
 	if XDGConfigDir := os.Getenv(configOverride); len(XDGConfigDir) != 0 {
 		return filepath.Join(XDGConfigDir, configFilePath)
 	}