Add support for drop-in config

Signed-off-by: Harshal Patil <harpatil@redhat.com>

store.go

@@ -3710,7 +3710,7 @@ func DefaultConfigFile() (string, error) {
 // the configuration in storeOptions.
 // Deprecated: Use types.ReloadConfigurationFile, which can return an error.
 func ReloadConfigurationFile(configFile string, storeOptions *types.StoreOptions) {
-	_ = types.ReloadConfigurationFile(configFile, storeOptions)
+	_ = types.ReloadConfigurationFile(configFile, storeOptions, true)
 }
 
 // GetDefaultMountOptions returns the default mountoptions defined in container/storage

types/options.go

@@ -49,6 +49,12 @@ var (
 	defaultConfigFile = SystemConfigFile
 	// DefaultStoreOptions is a reasonable default set of options.
 	defaultStoreOptions StoreOptions
+
+	// defaultOverrideConfigFile path to override the default system wide storage.conf file
+	defaultOverrideConfigFile = "/etc/containers/storage.conf"
+
+	// defaultDropInConfigDir path to the folder containing drop in config files
+	defaultDropInConfigDir = defaultOverrideConfigFile + ".d"
 )
 
 func loadDefaultStoreOptions() {
@@ -114,11 +120,53 @@ func loadDefaultStoreOptions() {
 
 // loadStoreOptions returns the default storage ops for containers
 func loadStoreOptions() (StoreOptions, error) {
-	storageConf, err := DefaultConfigFile()
+	baseConf, err := DefaultConfigFile()
+	if err != nil {
+		return defaultStoreOptions, err
+	}
+
+	// Load the base config file
+	baseOptions, err := loadStoreOptionsFromConfFile(baseConf)
 	if err != nil {
 		return defaultStoreOptions, err
 	}
-	return loadStoreOptionsFromConfFile(storageConf)
+
+	if _, err := os.Stat(defaultDropInConfigDir); err == nil {
+		// The directory exists, so merge the configuration from this directory
+		err = mergeConfigFromDirectory(&baseOptions, defaultDropInConfigDir)
+		if err != nil {
+			return defaultStoreOptions, err
+		}
+	} else if !os.IsNotExist(err) {
+		// There was an error other than the directory not existing
+		return defaultStoreOptions, err
+	}
+
+	return baseOptions, nil
+}
+
+func mergeConfigFromDirectory(baseOptions *StoreOptions, configDir string) error {
+	return filepath.Walk(configDir, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if info.IsDir() {
+			return nil
+		}
+
+		// Only consider files with .conf extension
+		if filepath.Ext(path) != ".conf" {
+			return nil
+		}
+
+		// Load drop-in options from the current file
+		err = ReloadConfigurationFile(path, baseOptions, false)
+		if err != nil {
+			return err
+		}
+
+		return nil
+	})
 }
 
 // usePerUserStorage returns whether the user private storage must be used.
@@ -399,7 +447,7 @@ func ReloadConfigurationFileIfNeeded(configFile string, storeOptions *StoreOptio
 		return nil
 	}
 
-	if err := ReloadConfigurationFile(configFile, storeOptions); err != nil {
+	if err := ReloadConfigurationFile(configFile, storeOptions, true); err != nil {
 		return err
 	}
 
@@ -412,7 +460,7 @@ func ReloadConfigurationFileIfNeeded(configFile string, storeOptions *StoreOptio
 
 // ReloadConfigurationFile parses the specified configuration file and overrides
 // the configuration in storeOptions.
-func ReloadConfigurationFile(configFile string, storeOptions *StoreOptions) error {
+func ReloadConfigurationFile(configFile string, storeOptions *StoreOptions, initializeOptions bool) error {
 	config := new(TomlConfig)
 
 	meta, err := toml.DecodeFile(configFile, &config)
@@ -428,8 +476,11 @@ func ReloadConfigurationFile(configFile string, storeOptions *StoreOptions) erro
 		}
 	}
 
-	// Clear storeOptions of previous settings
-	*storeOptions = StoreOptions{}
+	if initializeOptions {
+		// Clear storeOptions of previous settings
+		*storeOptions = StoreOptions{}
+	}
+
 	if config.Storage.Driver != "" {
 		storeOptions.GraphDriverName = config.Storage.Driver
 	}
@@ -519,8 +570,13 @@ func ReloadConfigurationFile(configFile string, storeOptions *StoreOptions) erro
 		storeOptions.PullOptions = config.Storage.Options.PullOptions
 	}
 
-	storeOptions.DisableVolatile = config.Storage.Options.DisableVolatile
-	storeOptions.TransientStore = config.Storage.TransientStore
+	if config.Storage.Options.DisableVolatile {
+		storeOptions.DisableVolatile = config.Storage.Options.DisableVolatile
+	}
+
+	if config.Storage.TransientStore {
+		storeOptions.TransientStore = config.Storage.TransientStore
+	}
 
 	storeOptions.GraphDriverOptions = append(storeOptions.GraphDriverOptions, cfg.GetGraphDriverOptions(storeOptions.GraphDriverName, config.Storage.Options)...)
 

types/options_darwin.go

@@ -8,8 +8,6 @@ const (
 	SystemConfigFile        = "/usr/share/containers/storage.conf"
 )
 
-var defaultOverrideConfigFile = "/etc/containers/storage.conf"
-
 // canUseRootlessOverlay returns true if the overlay driver can be used for rootless containers
 func canUseRootlessOverlay(home, runhome string) bool {
 	return false

types/options_freebsd.go

@@ -8,11 +8,6 @@ const (
 	SystemConfigFile        = "/usr/local/share/containers/storage.conf"
 )
 
-// defaultConfigFile path to the system wide storage.conf file
-var (
-	defaultOverrideConfigFile = "/usr/local/etc/containers/storage.conf"
-)
-
 // canUseRootlessOverlay returns true if the overlay driver can be used for rootless containers
 func canUseRootlessOverlay(home, runhome string) bool {
 	return false

types/options_linux.go

@@ -16,11 +16,6 @@ const (
 	SystemConfigFile        = "/usr/share/containers/storage.conf"
 )
 
-// defaultConfigFile path to the system wide storage.conf file
-var (
-	defaultOverrideConfigFile = "/etc/containers/storage.conf"
-)
-
 // canUseRootlessOverlay returns true if the overlay driver can be used for rootless containers
 func canUseRootlessOverlay(home, runhome string) bool {
 	// we check first for fuse-overlayfs since it is cheaper.

types/options_test.go

@@ -143,7 +143,7 @@ func TestSetRemapUIDsGIDsOpts(t *testing.T) {
 		},
 	}
 
-	err := ReloadConfigurationFile("./storage_test.conf", &remapOpts)
+	err := ReloadConfigurationFile("./storage_test.conf", &remapOpts, true)
 	require.NoError(t, err)
 	if !reflect.DeepEqual(uidmap, remapOpts.UIDMap) {
 		t.Errorf("Failed to set UIDMap: Expected %v Actual %v", uidmap, remapOpts.UIDMap)
@@ -185,7 +185,7 @@ remap-group = "%s"
 
 	mappings, err := idtools.NewIDMappings(user, user)
 	require.NoError(t, err)
-	err = ReloadConfigurationFile(configPath, &remapOpts)
+	err = ReloadConfigurationFile(configPath, &remapOpts, true)
 	require.NoError(t, err)
 	if !reflect.DeepEqual(mappings.UIDs(), remapOpts.UIDMap) {
 		t.Errorf("Failed to set UIDMap: Expected %v Actual %v", mappings.UIDs(), remapOpts.UIDMap)
@@ -199,10 +199,65 @@ func TestReloadConfigurationFile(t *testing.T) {
 	content := bytes.NewBufferString("")
 	logrus.SetOutput(content)
 	var storageOpts StoreOptions
-	err := ReloadConfigurationFile("./storage_broken.conf", &storageOpts)
+	err := ReloadConfigurationFile("./storage_broken.conf", &storageOpts, true)
 	require.NoError(t, err)
 	assert.Equal(t, storageOpts.RunRoot, "/run/containers/test")
 	logrus.SetOutput(os.Stderr)
 
 	assert.Equal(t, strings.Contains(content.String(), "Failed to decode the keys [\\\"foo\\\" \\\"storage.options.graphroot\\\"] from \\\"./storage_broken.conf\\\"\""), true)
 }
+
+func TestMergeConfigFromDirectory(t *testing.T) {
+	tempDir, err := os.MkdirTemp("", "testConfigDir")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tempDir)
+
+	// Creating a mix of files with .txt and .conf extensions
+	fileNames := []string{"config1.conf", "config2.conf", "ignore.txt", "config3.conf", "config4.txt"}
+	contents := []string{
+		`[storage]
+runroot = 'temp/run1'
+graphroot = 'temp/graph1'`,
+		`[storage]
+runroot = 'temp/run2'
+graphroot = 'temp/graph2'`,
+		`[storage]
+runroot = 'should/ignore'
+graphroot = 'should/ignore'`,
+		`[storage]
+runroot = 'temp/run3'`,
+		`[storage]
+runroot = 'temp/run4'
+graphroot = 'temp/graph4'`,
+	}
+	for i, fileName := range fileNames {
+		filePath := filepath.Join(tempDir, fileName)
+		if err := os.WriteFile(filePath, []byte(contents[i]), 0o666); err != nil {
+			t.Fatalf("Failed to write to temp file: %v", err)
+		}
+	}
+
+	// Set base options
+	baseOptions := StoreOptions{
+		RunRoot:        "initial/run",
+		GraphRoot:      "initial/graph",
+		TransientStore: true,
+	}
+
+	// Expected results after merging configurations from only .conf files
+	expectedOptions := StoreOptions{
+		RunRoot:        "temp/run3", // Last .conf file (config3.conf) read overrides earlier values
+		GraphRoot:      "temp/graph2",
+		TransientStore: true,
+	}
+
+	// Run the merging function
+	err = mergeConfigFromDirectory(&baseOptions, tempDir)
+	if err != nil {
+		t.Fatalf("Error merging config from directory: %v", err)
+	}
+
+	assert.DeepEqual(t, expectedOptions, baseOptions)
+}

types/options_windows.go

@@ -8,11 +8,6 @@ const (
 	SystemConfigFile        = "/usr/share/containers/storage.conf"
 )
 
-// defaultConfigFile path to the system wide storage.conf file
-var (
-	defaultOverrideConfigFile = "/etc/containers/storage.conf"
-)
-
 // canUseRootlessOverlay returns true if the overlay driver can be used for rootless containers
 func canUseRootlessOverlay(home, runhome string) bool {
 	return false

types/utils.go

@@ -66,7 +66,7 @@ func reloadConfigurationFileIfNeeded(configFile string, storeOptions *StoreOptio
 		return
 	}
 
-	ReloadConfigurationFile(configFile, storeOptions)
+	ReloadConfigurationFile(configFile, storeOptions, true)
 
 	prevReloadConfig.storeOptions = storeOptions
 	prevReloadConfig.mod = mtime