I always use environment variables, you can just use ENV['AWS_S3_KEY'] or whatever in your application code. Keep the keys in your local environment, and add se

I always use environment variables, you can just use ENV['AWS_S3_KEY'] or whatever in your application code. Keep the keys in your local environment, and add separate sets of keys to the staging / production environments. These files probably live in your project (.env or similar) in development but are gitignored. On production, they can be in your web-server or application configuration wherever appropriate, as long as they get loaded. If you are using a tool to manage deployment, you probably just need a step to verify on deploy the files / lines containing keys exist. I can't think of a widely-used programming language that doesn't support environment variables, though support may be less than exemplary in your language of choice. In ruby land, I use https://github.com/bkeepers/dotenv https://github.com/bkeepers/dotenv