confab

Contents

• Source code
• Readme
• License (MIT)
• confab
  • confab
• transforms
  • loadJSON
  • loadEnvironment
  • assign
  • required
  • defaults
  • freeze

Convention and Configuration

Confab is configuration-first by nature, as the details of configuration may vary widely from one project to the next. Nevertheless, the built-in transformations reflect certain opinions.

Namely, configuration should be:

• separate. Keeping configuration isolated from application logic eases deployment across multiple environments. Confab encourages developers to author complete configurations independent of the application.

• predictable. Like any other exception, errors in configuration should be immediately fatal. All confab transformations will fail immediately if unexpected conditions are encountered, while the required transformation can assert the presence of certain configuration keys. Similarly, the defaults transformation--while unquestionably useful--should be approached with care.

• immutable. The running application should not be concerned with configuration changes: if a change must be applied it should be applied to a new process. The freeze transformation guarantees that a config will not change after initialization.

• simple. File-based configs (JSON, YAML, etc.) make it easy to nest data inside multiple levels of keys. This is convenient for grouping like data, but it is not immediately clear how these data would map to (e.g.) environment variables or command-line arguments. Sub-configurations can enhance separation between unrelated concerns, but they should be used with care.

And one non-opinion

• Command-line parsing, and what impact (if any) arguments should have on the configuration is left as a project-specific decision. No transformations are provided for command-line support--but you can write your own!

 var confab = require('confab');
 var config = confab([
   confab.loadJSON([
     './config.' + process.env.NODE_ENV + '.json',
     './config.json'
   ]),

   confab.defaults({
     role: 'api',
     port: 3200
   })
 ]);

 console.log(config.role); // 'api'

var loadJSONTransform = confab.loadJSON([
 './config.json',
  __dirname + '/config.json',
  process.env.HOME + '/config.json'
]);

var envTransform = confab.loadEnvironment({
  'NODE_ENV': 'environment',
  'PORT': 'port'
});

var envTransform = confab.assign({
  port: '1492'
});

var defaultsTransform = confab.defaults({
  port: 3200,
  logLevel: 'debug'
});