nginx 泛域名配置，proxy_pass如何使用变量参数

[cn111]

server {
listen 80;
server_name *.m.abc.com;
if ( $host ~* ^([^\.]+)\.([^\.]+)\.([^\.]+)\.([^\.]+)$ ) {
set $subdomain $1;
set $mD2 $2.$3.$4;
set $d2 $2;
set $d3 $3;
}
location / {
rewrite ^/$ /index.jsp?cdm=$subdomain last;
#proxy_pass http://m.abc.com/;#这个正确访问网页
proxy_pass http://$mD2/; #502 bad Gateway
#proxy_pass http://$d2.abc.com/; #502 bad Gateway
#proxy_pass http://${d2}.${d3}.${d4}/; #502 bad Gateway
#proxy_pass $mD2/; #502 bad Gateway
}
}

[aabbabababaa]

location ^~ /wap/
{
if ($request_uri ~ /wap/(\d+)/(.+))
{
set $bucketid $1;
set $params $2;
}
proxy_pass http://mx$bucketid.test.com:6601/$params;
}

是要在local里面先set?

[blt_白骆驼]

?????????????????????????????????????????????????????????????? 删我的回复是什么意思？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？