How to make nginx redirect based on the value of a header?

The simplest way to do this is with an if directive. If there is a better way, please let me know, as people say the if directive is inefficient. Nginx converts dashes to underscores in headers, so X-Forwarded-Proto becomes $http_x_forwarded_proto.

server {
    listen 80;
    server_name example.com; # Replace this with your own hostname
    if ($http_x_forwarded_proto = "http") {
        return 301 https://example.com$request_uri;
    }

    # Rest of configuration goes here... 
}