env config implementation (#2024)

config/env/env.go

@@ -0,0 +1,48 @@
+// Package env provides config from environment variables
+package env
+
+import (
+	"encoding/json"
+	"os"
+	"strings"
+
+	"github.com/micro/go-micro/v3/config"
+)
+
+type envConfig struct{}
+
+// NewConfig returns new config
+func NewConfig() (*envConfig, error) {
+	return new(envConfig), nil
+}
+
+func formatKey(v string) string {
+	if len(v) == 0 {
+		return ""
+	}
+
+	v = strings.ToUpper(v)
+	return strings.Replace(v, ".", "_", -1)
+}
+
+func (c *envConfig) Get(path string, options ...config.Option) (config.Value, error) {
+	v := os.Getenv(formatKey(path))
+	if len(v) == 0 {
+		v = "{}"
+	}
+	return config.NewJSONValue([]byte(v)), nil
+}
+
+func (c *envConfig) Set(path string, val interface{}, options ...config.Option) error {
+	key := formatKey(path)
+	v, err := json.Marshal(val)
+	if err != nil {
+		return err
+	}
+	return os.Setenv(key, string(v))
+}
+
+func (c *envConfig) Delete(path string, options ...config.Option) error {
+	v := formatKey(path)
+	return os.Unsetenv(v)
+}