# Configuration Management

## Introduction

Configurations define property values used by the application to configure its behavior.

All configurations are located in `app/configs` directory. Environment-specific configurations (*e.g.*, NODE\_ENV=production) must reside in the `env` subdirectory and named after the target environment (*e.g.*, `app/configs/env/production`). Environment-specific configurations overwrite the values in general-purpose configuration files.

## Defining a Configuration

Define a configuration by exporting an object from the configuration file.

{% code title="app/configs/facebook.js" %}

```javascript
module.exports = {
  api_key: 'api key goes here'
};
```

{% endcode %}

## Accessing the Configuration

You access the configuration by looking it using the `blueprint.lookup()` method.  Because application configuration are the first resource loaded, it is safe to lookup a configuration at any time within in the servers lifetime. For example, the code snippet below shows how to access the Facebook API key from the configuration above:..

{% code title="app/controllers/facebook.js" %}

```javascript
const {Controller} = require ('@onhilltech/blueprint');

module.exports = Controller.extend ({
  apiKey: null,
  
  init () {
    this._super.call (this, ...arguments);
    const config = this.app.lookup ('config:facebook');
    this.apiKey = config.apiKey;
  }
});
```

{% endcode %}


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