Many plugins call on 3rd party services, and when they do those services often provide some form of credentials. About 9 times out of 10 those credentials get stored in wp-options table. Except I don’t want my security credentials in my database. Where you store you secrets can be deeply personal thing.
A common way to call credentials in plugin is something along the lines of:
$api_key = get_option( 'mysecretkey' ); define( 'SECRETKEY', $api_key );
If you are going to do that, then try this instead
if ( ! defined( 'SECRETKEY' ) ) {
$api_key = get_option( 'mysecretkey' );
define( 'SECRETKEY', $api_key );
}
By checking if it’s already defined before pulling it from DB, it allows me to add the API key in the wp-config.php and avoid putting it in my DB.
If you develop plugins that make use of third party services and storing API keys, then give your users the flexibility to store the keys where they want.