Rewrite Http to Https in Nginx

server {
       listen         80;
       server_name    example.com example2.com;
       return         301 https://$host$request_uri;
}

server {
       listen         443 ssl;
       server_name    example.com example2.com;
       ...
}

For ssl, usually we need

server {
        listen 443 ssl http2;
        listen [::]:443 ssl http2;

        ssl_certificate /etc/nginx/cert/certchain.crt;
        ssl_certificate_key /etc/nginx/cert/cert.key;

        ssl_session_cache shared:SSL:20m;
        ssl_session_timeout 60m;

        ssl_prefer_server_ciphers on;

        ssl_ciphers ECDH+AESGCM:ECDH+AES256:ECDH+AES128:DHE+AES128:!ADH:!AECDH:!MD5;

        #ssl_dhparam /etc/nginx/cert/dhparam.pem;

        ssl_protocols TLSv1 TLSv1.1 TLSv1.2;

        #ssl_stapling on;
        #ssl_stapling_verify on;
        #ssl_trusted_certificate /etc/nginx/cert/trustchain.crt;
        #resolver 8.8.8.8 8.8.4.4;

        #add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
        add_header Strict-Transport-Security "max-age=31536000" always;

        # Rest of your regular config goes here:
        # […]
}