Use .env values in Craft 3 plugin settings

Question

I’m writing a plugin and need some of its settings to be pulled from the .env file. According to the docs the following should work, but the getter isn’t getting called whenever the plugin’s youtubeApiKey setting is requested; it just keeps returning $YOUTUBE_API_KEY.

When I set the property visibility to protected instead of public, it does call the getter but also reveals the (sensitive) key in he admin settings panel.

class Settings extends Model
{
    public $youtubeApiKey = '$YOUTUBE_API_KEY';

    public function getYoutubeApiKey(): string
    {
        return Craft::parseEnv($this->youtubeApiKey);
    }

    public function behaviors()
    {
        return [
            'parser' => [
                'class' => EnvAttributeParserBehavior::class,
                'attributes' => ['youtubeApiKey'],
            ],
        ];
    }

    public function rules()
    {
        return [
            [['youtubeApiKey'], 'string'],
            [['youtubeApiKey'], 'default', 'value' => ''],
        ];
    }
}

I suppose my understanding of the settings getters is incorrect, but what I’m trying to achieve is for MyPlugin::getInstance()->getSettings()->youtubeApiKey to return the actual API key (not $YOUTUBE_API_KEY) and for the settings field (below) to display $YOUTUBE_API_KEY (not the actual API key).

{{ forms.textField({
    'id': 'youtubeApiKey',
    'label': 'YouTube API key',
    'name': 'youtubeApiKey',
    'suggestEnvVars': true,
    'value': settings.youtubeApiKey
}) }}

Answer 1

You could try declaring the variable $youtubeApiKey with no value set. Instead of using

public $youtubeApiKey = '$YOUTUBE_API_KEY';

try using

public $youtubeApiKey;