How to set variables with convict, and override them with env variables and npm arguments.

In config.js, the default port is 9999 and the default value of "foo" is "bar". In the start-script in package.json, the value of foo is overridden using the env-variable FOO, and the port-number is overridden with the argument port.

config.js

  httpServerPort: {
      doc     : "The port the server should bind to",
      format  : "port",
      default : 9999,
      env     : "PORT",
      arg     : "port"
  },

  foo: {
      doc: "just testing…",
      format: String,
      default: "bar",
      env: "FOO"
  }

start script

"scripts": {
  "start": "FOO=baz nodemon ./server.js --port=8888 | bunyan"
}

override-files

The environment variables can also be overridden using the development.json, production.json and local.json files. Switch between these during start-up, i.e. node server.js --env=production

fish

To modify env-variables directly using fish, start with env, i.e.: env FOO=barbaz node server.js