Configuration

When starting a project, you need to configure your application.

Simple settings

For small program, you could use the default settings which is provided by Prologue.

import prologue

var app = newApp()
app.run()

You may want to specify settings by yourself. Prologue provides newSettings function to create a new settings. The program below creates a new settings with debug = false. This will disable the default logging.

import prologue

let settings = newSettings(debug = false)
var app = newApp(settings = settings)
app.run()

You can also read settings from .env file. Prologue provides loadPrologueEnv to read data from .env file. You can use get or getOrDefault to retrieve the value.

import prologue

let
  env = loadPrologueEnv(".env")
  settings = newSettings(appName = env.getOrDefault("appName", "Prologue"),
                         debug = false,
                         port = Port(env.getOrDefault("port", 8080))
    )

var app = newApp(settings = settings)
app.run()

Config file

You need to specify a config file for a big project. Prologue provides loadSettings to read JSON file. You should give the path of the Json config file.

let settings = loadSettings(".config/config.debug.json")
var app = newApp(settings)

.config/config.debug.json

In config file, the prologue key must be present. The corresponding data will be used by framework. Among the corresponding data, the secretKey must be present and should not be empty. Otherwise, the program will raise exception. Other keys can be absent, they will be given a default value setting by Prologue.

Below is the type of settings:

address: string
port: int
debug: bool
reusePort: bool
appName: string
secretKey: string
bufSize: int

{
  "prologue": {
    "address": "",
    "port": 8080,
    "debug": true,
    "reusePort": true,
    "appName": "",
    "secretKey": "Set by yourself",
    "bufSize": 40960
  },
  "name": "debug"
}

Changing config file via environment variable

Prologue also supports automatically loading configure file by environment variables. The .config directory must be present in the current path(in the same directory as the main program). If you don't set the environment variable(namely PROLOGUE) or the value is default, the application will read .config/config.json file. Otherwise, if you set the PROLOGUE environment variable to custom, the application will read .config/config.custom.json. The common names includes debug and production. If the file doesn't exist, it will raise exception.

import prologue

var app = newAppQueryEnv()
app.run()