nginx负载均衡问题

负载均衡配置后，可以访问前台页面，但是输入用户名密码后闪一下就没了。

http {
include /etc/nginx/mime.types;
default_type application/octet-stream;
log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                  '$status $body_bytes_sent "$http_referer" '
                  '"$http_user_agent" "$http_x_forwarded_for"';

access_log  /var/log/nginx/access.log  main;

sendfile        on;
#tcp_nopush     on;

#keepalive_timeout  0;
keepalive_timeout  65;

#gzip  on;
# Load config files from the /etc/nginx/conf.d directory
# The default server is in conf.d/default.conf
# include /etc/nginx/conf.d/*.conf;
 upstream tomcats{
    server 192.168.42.128:8080;
    server 192.168.42.129:8080;
     }
server
{
listen 80;
server_name 192.168.42.130;
location / {
proxy_pass http://tomcats;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
}
}