package config import ( "log" "strings" "github.com/knadh/koanf" "github.com/knadh/koanf/parsers/yaml" "github.com/knadh/koanf/providers/env" "github.com/knadh/koanf/providers/file" "github.com/knadh/koanf/providers/structs" ) const ( defaultPrefix = "EB_" defaultDelimiter = "." defaultSeparator = "__" defaultYamlFilePath = "config.yml" ) var c Config type Option struct { Prefix string Delimiter string Separator string YamlFilePath string CallbackEnv func(string) string } // our environment variables must prefix with `EB_` // for nested .env should use `__` aka: EB__DB__HOST. func defaultCallbackEnv(source string) string { base := strings.ToLower(strings.TrimPrefix(source, defaultPrefix)) return strings.ReplaceAll(base, defaultSeparator, defaultDelimiter) } func init() { k := koanf.New(defaultDelimiter) // load default configuration from Default function if err := k.Load(structs.Provider(Default(), "koanf"), nil); err != nil { log.Fatalf("error loading default config: %s", err) } // load configuration from yaml file if err := k.Load(file.Provider(defaultYamlFilePath), yaml.Parser()); err != nil { log.Printf("error loading config from `config.yml` file: %s", err) } // load from environment variable if err := k.Load(env.Provider(defaultPrefix, defaultDelimiter, defaultCallbackEnv), nil); err != nil { log.Printf("error loading environment variables: %s", err) } if err := k.Unmarshal("", &c); err != nil { log.Fatalf("error unmarshaling config: %s", err) } } func C() Config { return c } func New(opt Option) Config { k := koanf.New(opt.Separator) if err := k.Load(structs.Provider(Default(), "koanf"), nil); err != nil { log.Fatalf("error loading default config: %s", err) } if err := k.Load(file.Provider(opt.YamlFilePath), yaml.Parser()); err != nil { log.Printf("error loading config from `config.yml` file: %s", err) } if err := k.Load(env.Provider(opt.Prefix, opt.Delimiter, opt.CallbackEnv), nil); err != nil { log.Printf("error loading environment variables: %s", err) } if err := k.Unmarshal("", &c); err != nil { log.Fatalf("error unmarshaling config: %s", err) } return c }