nginx reverse proxy config

user nginx;
worker_processes auto;
error_log /var/log/nginx/error.log;
pid /run/nginx.pid;

# Load dynamic modules. See /usr/share/nginx/README.dynamic.
include /usr/share/nginx/modules/*.conf;

events {
    worker_connections 1024;
    accept_mutex off;
}


http {
    include       mime.types;
    default_type  application/octet-stream;

    gzip on;
    gzip_vary on;
    gzip_min_length 1000;
    gzip_proxied any;
    gzip_types text/plain text/html text/css text/xml application/xml text/javascript application/x-javascript image/svg+xml;
    gzip_disable "MSIE [1-6]\.";

    proxy_redirect off;
    proxy_buffering off;

    log_format main '$remote_addr $http_x_forwarded_for - $remote_user [$time_local] '
                    '"$request" $status $body_bytes_sent "$http_referer" '
                    '"$http_user_agent"' ;

    # Large file uploads and performance improvements
    sendfile        on;
   #aio threads;
    directio 16M;

   #keepalive_timeout  0;
    keepalive_timeout  65;

    ## Upstream servers
    upstream ssl_pool_cloud {
        server back-end-server:port1;
    }

    server {
        listen 443 ssl http2 default_server;
        server_name  _;
        root /mnt/appdata/nginx/www;

        ssl_certificate /mnt/appdata/nginx/certs/ssl_certificate.crt;
        ssl_certificate_key /mnt/appdata/nginx/certs/ssl_certificate_key.key;

        ssl_session_cache    shared:SSL:10m;
        ssl_session_timeout  1h;
        ssl on;
        ssl_protocols  TLSv1.1 TLSv1.2;
        ssl_ciphers HIGH:!aNULL:!eNULL:!EXPORT:!CAMELLIA:!DES:!MD5:!PSK:!RC4;
        ssl_prefer_server_ciphers on;

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

        ## HTTPS config
        location / {
            return 301 https://$host$request_uri/cloud;
            #return 404;
            #index  index.html index.htm;
        }

        location /cloud {
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
            proxy_redirect http:// https://;
            proxy_ssl_verify off;
            proxy_max_temp_file_size 0;
            client_max_body_size 512M;
            proxy_pass http://ssl_pool_cloud;
        }
    }

    server {
        listen       80;
        server_name  _;
        root /mnt/appdata/nginx/www;
        access_log /var/log/nginx/access.log main;

        ## HTTP config
        location /cloud {
            return 301 https://$host$request_uri;
        }
    }
}