python----使用ftp遇到的“大坑”--＞ftplib.error_perm: 553 Can‘t open that file: No such file or directory

业务场景：

    需求呢简单来说就是：服务A在B服务器上运行，而服务A主要是将某些文件下载并传输到C服务器上，但是服务A不能直接运行在C服务器上

所以就使用了ftplib，paramiko

下面是部分代码：

#! encoding=utf-8
from ftplib import FTP
import os
import sys
import time
import socket
import paramiko

import serverConfig


class MyFTP:
    def __init__(self, host, port=21):
        self.host = host
        self.port = port
        self.ftp = FTP()
        # 重新设置下编码方式
        self.ftp.encoding = 'utf-8'
        self.log_file = open("log.txt", "a")
        self.file_list = []

    def login(self, username, password):
        try:
            timeout = 60
            socket.setdefaulttimeout(timeout)
            # 0主动模式 1 #被动模式
            self.ftp.set_pasv(True)
            # 打开调试级别2，显示详细信息
            # self.ftp.set_debuglevel(2)

            self.debug_print('----begin connect to %s' % self.host)
            self.ftp.connect(self.host, self.port)
            self.debug_print('------success connect to %s' % self.host)

            self.debug_print('--------begin login to %s' % self.host)
            self.ftp.login(username, password)
            self.debug_print('-----------success login to %s' % self.host)

            self.debug_print(self.ftp.welcome)
        except Exception as err:
            self.deal_error("FTP connect or login failed, error msg ->:：%s" % err)
            pass

    def is_same_size(self, local_file, remote_file):
        try:
            remote_file_size = self.ftp.size(remote_file)
        except Exception as err:
            # self.debug_print("is_same_size() 错误描述为：%s" % err)
            remote_file_size = -1

        try:
            local_file_size = os.path.getsize(local_file)
        except Exception as err:
            # self.debug_print("is_same_size() 错误描述为：%s" % err)
            local_file_size = -1

        self.debug_print('local_file_size:%d  , remote_file_size:%d' % (local_file_size, remote_file_size))
        if remote_file_size == local_file_size:
            return 1
        else:
            return 0

    def download_file(self, local_file, remote_file):
        self.debug_print("download_file()---> local_path = %s ,remote_path = %s" % (local_file, remote_file))

        if self.is_same_size(local_file, remote_file):
            self.debug_print('%s 文件大小相同，无需下载' % local_file)
            return
        else:
            try:
                self.debug_print('>>>>>>>>>>>>下载文件 %s ... ...' % local_file)
                buf_size = 1024
                file_handler = open(local_file, 'wb')
                self.ftp.retrbinary('RETR %s' % remote_file, file_handler.write, buf_size)
                file_handler.close()
            except Exception as err:
                self.debug_print('下载文件出错，出现异常：%s ' % err)
                return

    def download_file_tree(self, local_path, remote_path):
        print("download_file_tree()--->  local_path = %s ,remote_path = %s" % (local_path, remote_path))
        try:
            self.ftp.cwd(remote_path)
        except Exception as err:
            self.debug_print('远程目录%s不存在，继续...' % remote_path + " ,具体错误描述为：%s" % err)
            return

        if not os.path.isdir(local_path):
            self.debug_print('本地目录%s不存在，先创建本地目录' % local_path)
            os.makedirs(local_path)

        self.debug_print('切换至目录: %s' % self.ftp.pwd())

        self.file_list = []
        # 方法回调
        self.ftp.dir(self.get_file_list)

        remote_names = self.file_list
        self.debug_print('远程目录 列表: %s' % remote_names)
        for item in remote_names:
            file_type = item[0]
            file_name = item[1]
            local = os.path.join(local_path, file_name)
            if file_type == 'd':
                print("download_file_tree()---> 下载目录： %s" % file_name)
                self.download_file_tree(local, file_name)
            elif file_type == '-':
                print("download_file()---> 下载文件： %s" % file_name)
                self.download_file(local, file_name)
            self.ftp.cwd("..")
            self.debug_print('返回上层目录 %s' % self.ftp.pwd())
        return True

    def upload_file(self, local_file, remote_file):

        # if not os.path.isfile(local_file):
        #     self.debug_print('%s 不存在' % local_file)
        #     return
        #
        # if self.is_same_size(local_file, remote_file):
        #     self.debug_print('跳过相等的文件: %s' % local_file)
        #     return

        buf_size = 1024
        file_handler = open(local_file, 'rb')
        self.ftp.storbinary('STOR %s' % remote_file, file_handler, buf_size)
        file_handler.close()
        self.debug_print('upload: %s' % local_file + "success!")

    def mkdir(self, file_path):
        try:
            ssh = paramiko.SSHClient()
            ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
            ssh.connect(hostname=serverConfig.IP, port=22, username=serverConfig.USER, password=serverConfig.PASSWD)
        except Exception as e:
            self.debug_print("mkdir need ssh connect, but failed, error msg: -> %s" % e)
        else:
            ssh.exec_command('mkdir -p %s'% file_path)
            ssh.exec_command("chmod 777 %s" % file_path)

    def close(self):
        """ 退出ftp
        """
        self.debug_print("close()---> FTP logout success")
        self.ftp.quit()
        self.log_file.close()

    def debug_print(self, s):
        self.write_log(s)

    def deal_error(self, e):
        log_str = '发生错误: %s' % e
        self.write_log(log_str)
        sys.exit()

    def write_log(self, log_str):

        time_now = time.localtime()
        date_now = time.strftime('%Y-%m-%d', time_now)
        format_log_str = "%s ---> %s \n " % (date_now, log_str)
        print(format_log_str)
        self.log_file.write(format_log_str)


if __name__ == "__main__":
    my_ftp = MyFTP("xx.xx.xx.xx")
    my_ftp.login("ftp用户名", "ftp用户密码")

    # 下载单个文件
    # my_ftp.download_file("G:/ftp_test/XTCLauncher.apk", "/App/AutoUpload/ouyangpeng/I12/Release/XTCLauncher.apk")

    # 下载目录
    # my_ftp.download_file_tree("G:/ftp_test/", "App/AutoUpload/ouyangpeng/I12/")

    # 上传单个文件
    my_ftp.upload_file(r"C:\Users\ysten\Desktop\Ocean\pythonSpiders\test.jpg", r"/app/test.jpg")

    # 上传目录
    # my_ftp.upload_file_tree("G:/ftp_test/", "/App/AutoUpload/ouyangpeng/I12/")
    my_ftp.mkdir("/app/app")
    my_ftp.close()

以上代码主要实现了传输的功能，在我实现了功能以后找了两台服务器进行测试，测试过程中还是比较顺利的，能够正常实现，但是当放到我们线上后，莫名的就开始报错了。。。。。 

下面直接说引起这个错误的原因是什么？

因为我测试的时候没有指定ftp用户目录，默认是“/”，而我的业务逻辑就是从“/”根目录开始，动态创建多层目录，然后将其保存。

然而，运维将ftp用户的目录指定到了其他的目录，所以我的代码就找不到路径了，就报了上面那个错