config: add Validate func, small lint fixes

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

config/config.go

@@ -4,11 +4,16 @@ package config // import "go.unistack.org/micro/v3/config"
 import (
 	"context"
 	"errors"
+	"reflect"
 	"time"
 )
 
+type Validator interface {
+	Validate() error
+}
+
 // DefaultConfig default config
-var DefaultConfig Config = NewConfig()
+var DefaultConfig = NewConfig()
 
 // DefaultWatcherMinInterval default min interval for poll changes
 var DefaultWatcherMinInterval = 5 * time.Second
@@ -67,7 +72,59 @@ func Load(ctx context.Context, cs []Config, opts ...LoadOption) error {
 	return nil
 }
 
+// Validate runs Validate() error func for each struct field
+func Validate(ctx context.Context, cfg interface{}) error {
+	if cfg == nil {
+		return nil
+	}
+
+	if v, ok := cfg.(Validator); ok {
+		if err := v.Validate(); err != nil {
+			return err
+		}
+	}
+
+	sv := reflect.ValueOf(cfg)
+	if sv.Kind() == reflect.Ptr {
+		sv = sv.Elem()
+	}
+	if sv.Kind() != reflect.Struct {
+		return nil
+	}
+
+	typ := sv.Type()
+	for idx := 0; idx < typ.NumField(); idx++ {
+		fld := typ.Field(idx)
+		val := sv.Field(idx)
+		if !val.IsValid() || len(fld.PkgPath) != 0 {
+			continue
+		}
+
+		if v, ok := val.Interface().(Validator); ok {
+			if err := v.Validate(); err != nil {
+				return err
+			}
+		}
+
+		switch val.Kind() {
+		case reflect.Ptr:
+			if reflect.Indirect(val).Kind() == reflect.Struct {
+				if err := Validate(ctx, val.Interface()); err != nil {
+					return err
+				}
+			}
+		case reflect.Struct:
+			if err := Validate(ctx, val.Interface()); err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
+
 var (
+	// DefaultAfterLoad default func that runs after config load
 	DefaultAfterLoad = func(ctx context.Context, c Config) error {
 		for _, fn := range c.Options().AfterLoad {
 			if err := fn(ctx, c); err != nil {
@@ -79,7 +136,7 @@ var (
 		}
 		return nil
 	}
-
+	// DefaultAfterSave default func that runs after config save
 	DefaultAfterSave = func(ctx context.Context, c Config) error {
 		for _, fn := range c.Options().AfterSave {
 			if err := fn(ctx, c); err != nil {
@@ -91,7 +148,7 @@ var (
 		}
 		return nil
 	}
-
+	// DefaultBeforeLoad default func that runs before config load
 	DefaultBeforeLoad = func(ctx context.Context, c Config) error {
 		for _, fn := range c.Options().BeforeLoad {
 			if err := fn(ctx, c); err != nil {
@@ -103,11 +160,11 @@ var (
 		}
 		return nil
 	}
-
+	// DefaultBeforeSave default func that runs befora config save
 	DefaultBeforeSave = func(ctx context.Context, c Config) error {
 		for _, fn := range c.Options().BeforeSave {
 			if err := fn(ctx, c); err != nil {
-				c.Options().Logger.Errorf(ctx, "%s BeforeSavec err: %v", c.String(), err)
+				c.Options().Logger.Errorf(ctx, "%s BeforeSave err: %v", c.String(), err)
 				if !c.Options().AllowFail {
 					return err
 				}

config/default_test.go

@@ -8,30 +8,46 @@ import (
 	"go.unistack.org/micro/v3/config"
 )
 
-type Cfg struct {
+type cfg struct {
 	StringValue string `default:"string_value"`
 	IgnoreValue string `json:"-"`
-	StructValue struct {
-		StringValue string `default:"string_value"`
+	StructValue *cfgStructValue
+	IntValue    int `default:"99"`
+}
+
+type cfgStructValue struct {
+	StringValue string `default:"string_value"`
+}
+
+func (c *cfg) Validate() error {
+	if c.IntValue != 10 {
+		return fmt.Errorf("invalid IntValue %d != %d", 10, c.IntValue)
 	}
-	IntValue int `default:"99"`
+	return nil
+}
+
+func (c *cfgStructValue) Validate() error {
+	if c.StringValue != "string_value" {
+		return fmt.Errorf("invalid StringValue %s != %s", "string_value", c.StringValue)
+	}
+	return nil
 }
 
 func TestDefault(t *testing.T) {
 	ctx := context.Background()
-	conf := &Cfg{IntValue: 10}
-	blfn := func(ctx context.Context, cfg config.Config) error {
-		nconf, ok := cfg.Options().Struct.(*Cfg)
+	conf := &cfg{IntValue: 10}
+	blfn := func(_ context.Context, c config.Config) error {
+		nconf, ok := c.Options().Struct.(*cfg)
 		if !ok {
-			return fmt.Errorf("failed to get Struct from options: %v", cfg.Options())
+			return fmt.Errorf("failed to get Struct from options: %v", c.Options())
 		}
 		nconf.StringValue = "before_load"
 		return nil
 	}
-	alfn := func(ctx context.Context, cfg config.Config) error {
-		nconf, ok := cfg.Options().Struct.(*Cfg)
+	alfn := func(_ context.Context, c config.Config) error {
+		nconf, ok := c.Options().Struct.(*cfg)
 		if !ok {
-			return fmt.Errorf("failed to get Struct from options: %v", cfg.Options())
+			return fmt.Errorf("failed to get Struct from options: %v", c.Options())
 		}
 		nconf.StringValue = "after_load"
 		return nil
@@ -50,3 +66,19 @@ func TestDefault(t *testing.T) {
 	_ = conf
 	// t.Logf("%#+v\n", conf)
 }
+
+func TestValidate(t *testing.T) {
+	ctx := context.Background()
+	conf := &cfg{IntValue: 10}
+	cfg := config.NewConfig(config.Struct(conf))
+	if err := cfg.Init(); err != nil {
+		t.Fatal(err)
+	}
+	if err := cfg.Load(ctx); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := config.Validate(ctx, conf); err != nil {
+		t.Fatal(err)
+	}
+}

config/options.go

@@ -69,6 +69,7 @@ type LoadOptions struct {
 	Context  context.Context
 }
 
+// NewLoadOptions create LoadOptions struct with provided opts
 func NewLoadOptions(opts ...LoadOption) LoadOptions {
 	options := LoadOptions{}
 	for _, o := range opts {
@@ -221,8 +222,10 @@ type WatchOptions struct {
 	Coalesce bool
 }
 
+// WatchOption func signature
 type WatchOption func(*WatchOptions)
 
+// NewWatchOptions create WatchOptions struct with provided opts
 func NewWatchOptions(opts ...WatchOption) WatchOptions {
 	options := WatchOptions{
 		Context:     context.Background(),