META.md

Meta

Schema

meta:
  pkg: "main"                             # package name, default "main"
  container_type:          "Gontainer"    # autogenerated type, default "Gontainer"
  container_constructor:   "NewGontainer" # autogenerated constructor, default "NewGontainer"
  default_must_getter: false              # whether must-getters should be auto-generated for services by default, default false
  imports:                                # aliases for imports in YAML, default empty
    "http": "server/http"
  functions:                              # functions that can be used in parameters
    "env": "os.Getenv"

Functions

Each function must return a single or two values. If the function returns two values, the second value should be of type error. If the second value is not nil, the error will be reported.

Built-in functions

env

parameters:
    appHost:  '%env("HOST")%'              # returns the error when the env var does not exist
    appHost2: '%env("HOST", "localhost")%' # returns "localhost" when the env var does not exist

func env(key string, def ...string) (string, error) {
    val, ok := os.LookupEnv(key)
    if !ok {
        if len(def) > 0 {
            return def[0], nil
        }
        return "", fmt.Errorf("environment variable %+q does not exist", key)
    }
    return val, nil
}

envInt

func envInt(key string, def ...int) (int, error) {
    val, ok := os.LookupEnv(key)
    if !ok {
        if len(def) > 0 {
            return def[0], nil
        }
        return 0, fmt.Errorf("environment variable %+q does not exist", key)
    }
    res, err := strconv.Atoi(val)
    if err != nil {
        return 0, fmt.Errorf("cannot cast env(%+q) to int: %s", key, err.Error())
    }
    return res, nil
}

todo

parameters:
    appPort: '%todo()%'                  # returns the error "parameter todo" always
    appPort2: '%todo("in development")%' # returns the error "in development" always

func todo(params ...string) (interface{}, error) {
    if len(params) > 0 {
        return nil, errors.New(params[0])
    }
    return nil, errors.New("parameter todo")
}

You can mark a parameter as todo, it means that Gontainer won't print an error param "myParam" does not exist during the compilation time, but accessing that parameter during the execution time reports an error. Use that if you want to define the param value during the execution time.

parameters:
  startedAt: "%todo()%"

service:
  application:
    value: "MyApplication{}"
    fields:
      StartedAt: "%startedAt%"

g := gontainer.New()
g.OverrideParam("startedAt", container.NewDependencyValue(time.Now()))