nginx use cookie as cache key

nginx.conf

# guide https://www.nginx.com/blog/nginx-caching-guide/
# document for variable http://nginx.org/en/docs/http/ngx_http_core_module.html#Variables
server {
    ...
    location / {
        # point is cookie name shouldn't contain - (hyphen), it cause wrong hash key.
        # example $cookie_gist_var
        proxy_cache_key $proxy_host$request_uri$cookie_{cookieNameShouldNotContainHyphen};
        ...
    }
}