initial import

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

env.go

@@ -0,0 +1,150 @@
+package env
+
+import (
+	"github.com/unistack-org/micro/v3/config"
+	"context"
+	"reflect"
+	"os"
+	"strconv"
+)
+
+var (
+	DefaultStructTag = "env"
+)
+
+type envConfig struct {
+	opts config.Options
+}
+
+func (c *envConfig) Options() config.Options {
+	return c.opts
+}
+
+
+func (c *envConfig) Init(opts...config.Option) error {
+	for _, o := range opts {
+		o(&c.opts)
+	}
+	return nil
+}
+
+func (c *envConfig) Load(ctx context.Context) error {
+	fields := reflect.TypeOf(c.opts.Struct).Elem()
+	values := reflect.ValueOf(c.opts.Struct).Elem()
+
+	for idx := 0; idx < fields.NumField(); idx++ {
+		field := fields.Field(idx)
+		value := values.Field(idx)
+		if !value.CanSet() {
+			continue
+		}
+		tag, ok := field.Tag.Lookup(c.opts.StructTag)
+		if !ok {
+			continue
+		}
+		val, ok := os.LookupEnv(tag)
+		if !ok {
+			continue
+		}
+		switch value.Kind() {
+		case reflect.Bool:
+			v, err := strconv.ParseBool(val)
+			if err != nil {
+				return err
+			}
+			value.Set(reflect.ValueOf(v))
+		case reflect.String:
+			value.Set(reflect.ValueOf(val))
+		case reflect.Float32:
+			v, err := strconv.ParseFloat(val, 32)
+			if err != nil {
+				return err
+			}
+			value.Set(reflect.ValueOf(v))
+		case reflect.Float64:
+			v, err := strconv.ParseFloat(val, 64)
+			if err != nil {
+				return err
+			}
+			value.Set(reflect.ValueOf(v))
+		case reflect.Int:
+			v, err := strconv.ParseInt(val, 10, 0)
+			if err != nil {
+				return err
+			}
+			value.Set(reflect.ValueOf(v))
+		case reflect.Int8:
+			v, err := strconv.ParseInt(val, 10, 8)
+			if err != nil {
+				return err
+			}
+			value.Set(reflect.ValueOf(v))
+		case reflect.Int16:
+			v, err := strconv.ParseInt(val, 10, 16)
+			if err != nil {
+				return err
+			}
+			value.Set(reflect.ValueOf(v))
+		case reflect.Int32:
+			v, err := strconv.ParseInt(val, 10, 32)
+			if err != nil {
+				return err
+			}
+			value.Set(reflect.ValueOf(v))
+		case reflect.Int64:
+			v, err := strconv.ParseInt(val, 10, 64)
+			if err != nil {
+				return err
+			}
+			value.Set(reflect.ValueOf(v))
+		case reflect.Uint:
+			v, err := strconv.ParseUint(val, 10, 0)
+			if err != nil {
+				return err
+			}
+			value.Set(reflect.ValueOf(v))
+		case reflect.Uint8:
+			v, err := strconv.ParseUint(val, 10, 8)
+			if err != nil {
+				return err
+			}
+			value.Set(reflect.ValueOf(v))
+		case reflect.Uint16:
+			v, err := strconv.ParseUint(val, 10, 16)
+			if err != nil {
+				return err
+			}
+			value.Set(reflect.ValueOf(v))
+		case reflect.Uint32:
+			v, err := strconv.ParseUint(val, 10, 32)
+			if err != nil {
+				return err
+			}
+			value.Set(reflect.ValueOf(v))
+		case reflect.Uint64:
+			v, err := strconv.ParseUint(val, 10, 64)
+			if err != nil {
+				return err
+			}
+			value.Set(reflect.ValueOf(v))
+		}
+	}
+
+	return nil
+}
+
+func (c *envConfig) Save(ctx context.Context) error {
+	return nil
+}
+
+func (c *envConfig) String() string {
+	return "env"
+}
+
+func NewConfig(opts...config.Option) config.Config {
+	options := config.NewOptions(opts...)
+	if len(options.StructTag) == 0 {
+		options.StructTag = DefaultStructTag
+	}
+	return &envConfig{opts:options}
+}