在Nanobox中，pip安装遇到NewConnectionError。无法使用pip安装软件包。

Question

我为运行Ubuntu 18.04.1。的本地计算机安装了nanobox。 Nanobox使用本地docker。因此，我安装了Docker版本18.06.1。我能够运行使用boxfile.yml文件的nanobox，该文件告诉nanobox运行python引擎。之后，我尝试使用pip安装新软件包，但返回了NewConnectionError。我可以在本地计算机上使用pip安装新软件包，但在nanobox中失败。

dinesh@dinesh-Inspiron-5559:~/Desktop/Test$ nanobox run
Preparing environment :

Test (local) :
  ✓ Restoring App

Preparing environment :

Building dev environment :
  ✓ Starting docker container
  ✓ Configuring


                                   **
                                ********
                             ***************
                          *********************
                            *****************
                          ::    *********    ::
                             ::    ***    ::
                           ++   :::   :::   ++
                              ++   :::   ++
                                 ++   ++
                                    +
                    _  _ ____ _  _ ____ ___  ____ _  _
                    |\ | |__| |\ | |  | |__) |  |  \/
                    | \| |  | | \| |__| |__) |__| _/\_

--------------------------------------------------------------------------------
+ You are in a Linux container
+ Your local source code has been mounted into the container
+ Changes to your code in either the container or desktop will be mirrored
+ If you run a server, access it at >> 172.20.0.5
--------------------------------------------------------------------------------

/app $ pip install Flask
Collecting Flask
  Retrying (Retry(total=4, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f2b29152d10>: Failed to establish a new connection: [Errno 113] No route to host',)': /simple/flask/
  Retrying (Retry(total=3, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f2b291525d0>: Failed to establish a new connection: [Errno 113] No route to host',)': /simple/flask/
  Retrying (Retry(total=2, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f2b291521d0>: Failed to establish a new connection: [Errno 113] No route to host',)': /simple/flask/
  Retrying (Retry(total=1, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f2b29159f90>: Failed to establish a new connection: [Errno 113] No route to host',)': /simple/flask/
  Retrying (Retry(total=0, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f2b29159610>: Failed to establish a new connection: [Errno 113] No route to host',)': /simple/flask/
  Could not find a version that satisfies the requirement Flask (from versions: )
No matching distribution found for Flask