detect environment type (production, development or staging) in Silex
I don't have experience with Silex but I always use environment variables for this. Then in your application you can get the current environment with:
getenv('ENVIRONMENT')
Silex by itself doesn't have environments, only has a debug mode. In order to know if your application is in debug mode you have the $app['debug'] variable.
Having said that nothing prevents you to create your own environment variable in, let's say $app['env'] (yes very original...). So everywhere you need to know which environment are you running you can use the $app['env'] variable.
In order to initialize this variable and following the silex skeleton you can have (in the web folder, your DocumentRoot) an index.php, index_dev.php, index_stg.php where you set the $app['env'] accordingly before calling $app->run().
Or you can use the technique explained by @WimMostmans and use a real environment variable :-)