Implement Config Manager

go.mod

@@ -15,6 +15,9 @@ require (
 	github.com/go-playground/validator/v10 v10.11.2 // indirect
 	github.com/klauspost/compress v1.10.3 // indirect
 	github.com/leodido/go-urn v1.2.1 // indirect
+	github.com/r3labs/diff/v3 v3.0.1 // indirect
+	github.com/vmihailenco/msgpack/v5 v5.3.5 // indirect
+	github.com/vmihailenco/tagparser/v2 v2.0.0 // indirect
 	golang.org/x/crypto v0.5.0 // indirect
 	golang.org/x/sys v0.4.0 // indirect
 	golang.org/x/text v0.6.0 // indirect

go.sum

@@ -48,6 +48,8 @@ github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421/go.mod h1:6dJ
 github.com/modern-go/reflect2 v0.0.0-20180701023420-4b7aa43c6742 h1:Esafd1046DLDQ0W1YjYsBW+p8U2u7vzgW2SQVmlNazg=
 github.com/modern-go/reflect2 v0.0.0-20180701023420-4b7aa43c6742/go.mod h1:bx2lNnkwVCuqBIxFjflWJWanXIb3RllmbCylyMrvgv0=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/r3labs/diff/v3 v3.0.1 h1:CBKqf3XmNRHXKmdU7mZP1w7TV0pDyVCis1AUHtA4Xtg=
+github.com/r3labs/diff/v3 v3.0.1/go.mod h1:f1S9bourRbiM66NskseyUdo0fTmEE0qKrikYJX63dgo=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
@@ -56,6 +58,10 @@ github.com/ugorji/go v1.1.7 h1:/68gy2h+1mWMrwZFeD1kQialdSzAb432dtpeJ42ovdo=
 github.com/ugorji/go v1.1.7/go.mod h1:kZn38zHttfInRq0xu/PH0az30d+z6vm202qpg1oXVMw=
 github.com/ugorji/go/codec v1.1.7 h1:2SvQaVZ1ouYrrKKwoSk2pzd4A9evlKJb9oTL+OaLUSs=
 github.com/ugorji/go/codec v1.1.7/go.mod h1:Ax+UKWsSmolVDwsd+7N3ZtXu+yMGCf907BLYF3GoBXY=
+github.com/vmihailenco/msgpack/v5 v5.3.5 h1:5gO0H1iULLWGhs2H5tbAHIZTV8/cYafcFOr9znI5mJU=
+github.com/vmihailenco/msgpack/v5 v5.3.5/go.mod h1:7xyJ9e+0+9SaZT0Wt1RGleJXzli6Q/V5KbhBonMG9jc=
+github.com/vmihailenco/tagparser/v2 v2.0.0 h1:y09buUbR+b5aycVFQs/g70pqKVZNBmxwAhO7/IwNM9g=
+github.com/vmihailenco/tagparser/v2 v2.0.0/go.mod h1:Wri+At7QHww0WTrCBeu4J6bNtoV6mEfg5OIWRZA9qds=
 go4.org/netipx v0.0.0-20230125063823-8449b0a6169f h1:ketMxHg+vWm3yccyYiq+uK8D3fRmna2Fcj+awpQp84s=
 go4.org/netipx v0.0.0-20230125063823-8449b0a6169f/go.mod h1:tgPU4N2u9RByaTN3NC2p9xOzyFpte4jYwsIIRF7XlSc=
 golang.org/x/crypto v0.5.0 h1:U/0M97KRkSFvyD/3FSmdP5W5swImpNgle/EHFhOsQPE=

internal/config/apply.go

@@ -0,0 +1,41 @@
+package config
+
+import (
+	"fmt"
+
+	"golang.org/x/exp/slog"
+	"nfsense.net/nfsense/internal/definitions"
+)
+
+// ApplyPendingChanges Takes all pending Changes and Tries to Apply them using the Registered Apply Functions.
+// In Case of error it Attempts to Revert to the Current Config
+func (m *ConfigManager) ApplyPendingChanges() error {
+	slog.Info("Applying Pending Changes...")
+	for _, fn := range m.applyFunctions {
+		err := fn(*m.pendingConfig)
+		if err != nil {
+			slog.Error("Applying Pending Changes", err)
+			err2 := revertToCurrent(m)
+			if err2 != nil {
+				slog.Error("Reverting Error", err2)
+				return fmt.Errorf("Apply Error %w; Reverting Error %w", err, err2)
+			}
+			return err
+		}
+	}
+	return nil
+}
+
+func revertToCurrent(m *ConfigManager) error {
+	for _, fn := range m.applyFunctions {
+		err := fn(*m.currentConfig)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (m *ConfigManager) RegisterApplyFunction(fn func(definitions.Config) error) {
+	m.applyFunctions = append(m.applyFunctions, fn)
+}

internal/config/diff.go

@@ -0,0 +1,11 @@
+package config
+
+import "github.com/r3labs/diff/v3"
+
+func (m *ConfigManager) AreChangesPending() bool {
+	return diff.Changed(m.currentConfig, m.pendingConfig)
+}
+
+func (m *ConfigManager) GetPendingChangelog() (diff.Changelog, error) {
+	return diff.Diff(m.currentConfig, m.pendingConfig)
+}

internal/config/discard.go

@@ -0,0 +1,6 @@
+package config
+
+func (m *ConfigManager) DiscardPendingConfig() error {
+	m.pendingConfig = m.currentConfig.Clone()
+	return nil
+}

internal/config/get.go

@@ -0,0 +1,11 @@
+package config
+
+import "nfsense.net/nfsense/internal/definitions"
+
+func (m *ConfigManager) GetCurrentConfig() definitions.Config {
+	return *m.currentConfig.Clone()
+}
+
+func (m *ConfigManager) GetPendingConfig() definitions.Config {
+	return *m.pendingConfig.Clone()
+}

internal/config/load.go

@@ -0,0 +1,57 @@
+package config
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+
+	"nfsense.net/nfsense/internal/definitions"
+)
+
+func (m *ConfigManager) LoadCurrentConfigFromDisk() error {
+	var config definitions.Config
+	configFile, err := os.Open(m.currentConfigFilePath)
+	if err != nil {
+		return fmt.Errorf("opening Config File %w", err)
+	}
+	defer configFile.Close()
+
+	jsonParser := json.NewDecoder(configFile)
+	jsonParser.DisallowUnknownFields()
+	err = jsonParser.Decode(&config)
+	if err != nil {
+		return fmt.Errorf("decoding Config File %w", err)
+	}
+
+	err = definitions.ValidateConfig(&config)
+	if err != nil {
+		return fmt.Errorf("validating Config: %w", err)
+	}
+
+	m.currentConfig = &config
+	return nil
+}
+
+func (m *ConfigManager) LoadPendingConfigFromDisk() error {
+	var config definitions.Config
+	configFile, err := os.Open(m.pendingConfigFilePath)
+	if err != nil {
+		return fmt.Errorf("opening Config File %w", err)
+	}
+	defer configFile.Close()
+
+	jsonParser := json.NewDecoder(configFile)
+	jsonParser.DisallowUnknownFields()
+	err = jsonParser.Decode(&config)
+	if err != nil {
+		return fmt.Errorf("decoding Config File %w", err)
+	}
+
+	err = definitions.ValidateConfig(&config)
+	if err != nil {
+		return fmt.Errorf("validating Config: %w", err)
+	}
+
+	m.pendingConfig = &config
+	return nil
+}

internal/config/manager.go

@@ -0,0 +1,29 @@
+package config
+
+import (
+	"sync"
+
+	"nfsense.net/nfsense/internal/definitions"
+)
+
+type ConfigManager struct {
+	currentConfigFilePath string
+	pendingConfigFilePath string
+
+	currentConfig *definitions.Config
+	pendingConfig *definitions.Config
+
+	transactionMutex sync.Mutex
+
+	applyFunctions []func(definitions.Config) error
+}
+
+func CreateConfigManager() *ConfigManager {
+	manager := ConfigManager{
+		currentConfigFilePath: "config.json",
+		pendingConfigFilePath: "pending.json",
+		currentConfig:         &definitions.Config{},
+		pendingConfig:         &definitions.Config{},
+	}
+	return &manager
+}

internal/config/transaction.go

@@ -0,0 +1,55 @@
+package config
+
+import (
+	"fmt"
+	"sync"
+
+	"nfsense.net/nfsense/internal/definitions"
+)
+
+type ConfigTransaction struct {
+	finished      bool
+	mutex         sync.Mutex
+	configManager *ConfigManager
+	changes       *definitions.Config
+}
+
+func (m *ConfigManager) StartTransaction() (*ConfigTransaction, *definitions.Config) {
+	m.transactionMutex.Lock()
+	confCopy := m.pendingConfig.Clone()
+	return &ConfigTransaction{
+		configManager: m,
+		changes:       confCopy,
+	}, confCopy
+}
+
+func (t *ConfigTransaction) Commit() error {
+	t.mutex.Lock()
+	defer t.mutex.Unlock()
+
+	if t.finished {
+		return fmt.Errorf("transaction already finished")
+	}
+
+	t.finished = true
+	defer t.configManager.transactionMutex.Unlock()
+
+	err := definitions.ValidateConfig(t.changes)
+	if err != nil {
+		return fmt.Errorf("validating Config before Apply: %w", err)
+	}
+
+	t.configManager.pendingConfig = t.changes.Clone()
+
+	return nil
+}
+
+func (t *ConfigTransaction) Discard() {
+	t.mutex.Lock()
+	defer t.mutex.Unlock()
+
+	if !t.finished {
+		t.finished = true
+		t.configManager.transactionMutex.Unlock()
+	}
+}