Parse facebook share counter using nginx with lua extension

knife-facebook-lua.conf

location /facebook {
    set $token "href=${arg_id}&layout=button_count&locale=en_US";

    resolver 1.1.1.1;

    proxy_pass https://www.facebook.com/plugins/like.php?$token;
    proxy_ignore_headers Expires;
    proxy_ignore_headers Cache-Control;

    proxy_hide_header Content-Type;
    proxy_hide_header Content-Security-Policy;
    proxy_hide_header X-content-Type-Options;

    proxy_set_header Accept-Encoding "";
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

    lua_need_request_body on;
    lua_use_default_type off;

    header_filter_by_lua_block {
        ngx.header.content_length = nil
    }

    add_header Content-Type "application/json";

    body_filter_by_lua_block {
        ngx.ctx.buffered = (ngx.ctx.buffered or "") .. ngx.arg[1]

        ngx.arg[1] = nil

        if ngx.arg[2] then
            local count = ngx.re.match(ngx.ctx.buffered, '>Like</span><span.+?>([^<]+)<', 's')

            if count then
                ngx.arg[1] = 'knifeFacebookCount({"engagement":{"custom":' .. count[1] .. '}})'
            else
                ngx.arg[1] = 'knifeFacebookCount({"error":"Facebook parse error"})'
            end
        end
    }
}

Use sudo apt install nginx-extras to install nginx-lua module.
To receive counter follow link http://example.com/facebook-share/?href=https%3A%2F%2Fknife.media%2Fsmells-in-culture%2F