Refactor Toml config handling

This change refactors the toml config file handlig for runtimes
such as containerd or crio. A toml.Loader is introduced that
encapsulates loading the required file.

This can be extended to allow other mechanisms for loading
loading the current config.

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

pkg/config/engine/crio/crio.go

@@ -19,10 +19,9 @@ package crio
 import (
 	"fmt"
 
-	"github.com/pelletier/go-toml"
-
 	"github.com/NVIDIA/nvidia-container-toolkit/internal/logger"
 	"github.com/NVIDIA/nvidia-container-toolkit/pkg/config/engine"
+	"github.com/NVIDIA/nvidia-container-toolkit/pkg/config/toml"
 )
 
 // Config represents the cri-o config
@@ -39,8 +38,23 @@ func New(opts ...Option) (engine.Interface, error) {
 	for _, opt := range opts {
 		opt(b)
 	}
+	if b.logger == nil {
+		b.logger = logger.New()
+	}
+	if b.configSource == nil {
+		b.configSource = toml.FromFile(b.path)
+	}
 
-	return b.build()
+	tomlConfig, err := b.configSource.Load()
+	if err != nil {
+		return nil, err
+	}
+
+	cfg := Config{
+		Tree:   tomlConfig,
+		Logger: b.logger,
+	}
+	return &cfg, nil
 }
 
 // AddRuntime adds a new runtime to the crio config
@@ -115,22 +129,3 @@ func (c *Config) RemoveRuntime(name string) error {
 	*c.Tree = config
 	return nil
 }
-
-// Set sets the specified cri-o option.
-func (c *Config) Set(key string, value interface{}) {
-	config := *c.Tree
-	config.Set(key, value)
-	*c.Tree = config
-}
-
-// Save writes the config to the specified path
-func (c Config) Save(path string) (int64, error) {
-	config := c.Tree
-	output, err := config.Marshal()
-	if err != nil {
-		return 0, fmt.Errorf("unable to convert to TOML: %v", err)
-	}
-
-	n, err := engine.Config(path).Write(output)
-	return int64(n), err
-}

pkg/config/engine/crio/crio_test.go

@@ -19,9 +19,10 @@ package crio
 import (
 	"testing"
 
-	"github.com/pelletier/go-toml"
 	testlog "github.com/sirupsen/logrus/hooks/test"
 	"github.com/stretchr/testify/require"
+
+	"github.com/NVIDIA/nvidia-container-toolkit/pkg/config/toml"
 )
 
 func TestAddRuntime(t *testing.T) {
@@ -126,20 +127,20 @@ func TestAddRuntime(t *testing.T) {
 
 	for _, tc := range testCases {
 		t.Run(tc.description, func(t *testing.T) {
-			config, err := toml.Load(tc.config)
+			cfg, err := toml.Load(tc.config)
 			require.NoError(t, err)
 			expectedConfig, err := toml.Load(tc.expectedConfig)
 			require.NoError(t, err)
 
 			c := &Config{
 				Logger: logger,
-				Tree:   config,
+				Tree:   cfg,
 			}
 
 			err = c.AddRuntime("test", "/usr/bin/test", tc.setAsDefault)
 			require.NoError(t, err)
 
-			require.EqualValues(t, expectedConfig.String(), config.String())
+			require.EqualValues(t, expectedConfig.String(), cfg.String())
 		})
 	}
 }

pkg/config/engine/crio/option.go

@@ -17,17 +17,14 @@
 package crio
 
 import (
-	"fmt"
-	"os"
-
-	"github.com/pelletier/go-toml"
-
 	"github.com/NVIDIA/nvidia-container-toolkit/internal/logger"
+	"github.com/NVIDIA/nvidia-container-toolkit/pkg/config/toml"
 )
 
 type builder struct {
-	logger logger.Interface
-	path   string
+	logger       logger.Interface
+	configSource toml.Loader
+	path         string
 }
 
 // Option defines a function that can be used to configure the config builder
@@ -47,48 +44,9 @@ func WithPath(path string) Option {
 	}
 }
 
-func (b *builder) build() (*Config, error) {
-	if b.logger == nil {
-		b.logger = logger.New()
+// WithConfigSource sets the TOML source for the config.
+func WithConfigSource(configSource toml.Loader) Option {
+	return func(b *builder) {
+		b.configSource = configSource
 	}
-	if b.path == "" {
-		empty := toml.Tree{}
-		c := Config{
-			Tree:   &empty,
-			Logger: b.logger,
-		}
-		return &c, nil
-	}
-
-	return b.loadConfig(b.path)
-}
-
-// loadConfig loads the cri-o config from disk
-func (b *builder) loadConfig(config string) (*Config, error) {
-	b.logger.Infof("Loading config: %v", config)
-
-	info, err := os.Stat(config)
-	if os.IsExist(err) && info.IsDir() {
-		return nil, fmt.Errorf("config file is a directory")
-	}
-
-	if os.IsNotExist(err) {
-		b.logger.Infof("Config file does not exist; using empty config")
-		config = "/dev/null"
-	} else {
-		b.logger.Infof("Loading config from %v", config)
-	}
-
-	cfg, err := toml.LoadFile(config)
-	if err != nil {
-		return nil, err
-	}
-
-	b.logger.Infof("Successfully loaded config")
-
-	c := Config{
-		Tree:   cfg,
-		Logger: b.logger,
-	}
-	return &c, nil
 }