你可以使用 rewrite 重写你的请求路径

    location / {
        rewrite ^/pages/\d+_index\.json /pages/index.json break;
        proxy_pass http://127.0.0.1:8080;
    }
    # 测试下 会返回重写后的 url /pages/index.json
    location = /pages/index.json {
        return 200 $request_uri;
    }

我找到了两种解决的方法
rewrite:

location ~ ^/pages/{
     rewrite ^/pages/(\d+)/\d+_index.json   http://$host/pages/$1/index.json break;
}

proxy_pass

location ~ ^/pages/(\d+)/\d+_index.json$ {
    proxy_pass http://$host/pages/$1/index.json;
}