Nginx Redirect HTTP to HTTPS automatiquement pour les sous-domaines

J'essaie de rediriger tout mon trafic de http a https automatiquement. Comment puis-je faire une redirection 301 sur tous mes domaines et sous-domaines ?

Voici le fichier de configuration NGNIX

upstream app_server {
    server unix:/run/DigitalOceanOneClick/unicorn.sock fail_timeout=0;
}

server {
        listen 80 default_server;
        listen [::]:80 default_server;
        server_name sprintsocial.io app.sprintsocial.io admin.sprintsocial.io;
#       return 301 https://$server_name$request_uri;
}

server {
    #listen   80;
    listen 443;
    root /home/rails/sprintsocial/public;
    #server_name _;
    server_name sprintsocial.io app.sprintsocial.io admin.sprintsocial.io;
    ssl on;
    ssl_certificate /home/sprintsocial.io.chained.crt;
    ssl_certificate_key /home/sprintsocial.io.key;
    index index.htm index.html;
#    return 301 https://$server_name$request_uri;

#    rewrite ^/(.*) https://app.sprintsocial.io/$1 permanent;
#    rewrite ^/(.*) https://admin.sprintsocial.io/$1 permanent;

    location / {
            try_files $uri/index.html $uri.html $uri @app;
    }

    location ~* ^.+\.(jpg|jpeg|gif|png|ico|zip|tgz|gz|rar|bz2|doc|xls|exe|pdf|ppt|txt|tar|mid|midi|wav|bmp|rtf|mp3|flv|mpeg|avi)$ {
                    try_files $uri @app;
            }

     location @app {
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header Host $http_host;
            proxy_redirect off;
            proxy_pass http://app_server;
    }
}