错误如下，遇到第二次了，而且看到网上很多回答并不管用，当然也可能是对应的问题不太相同。
Collecting requests (from -r requirements.txt (line 1))
Retrying (Retry(total=4, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f443a504350>: Failed to establish a new connection: [Errno -3] Temporary failure in name resolution',)': /simple/requests/
Retrying (Retry(total=3, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f443a504990>: Failed to establish a new connection: [Errno -3] Temporary failure in name resolution',)': /simple/requests/
Retrying (Retry(total=2, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f443a504390>: Failed to establish a new connection: [Errno -3] Temporary failure in name resolution',)': /simple/requests/
Retrying (Retry(total=1, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f443a504090>: Failed to establish a new connection: [Errno -3] Temporary failure in name resolution',)': /simple/requests/
Retrying (Retry(total=0, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f443a504a50>: Failed to establish a new connection: [Errno -3] Temporary failure in name resolution',)': /simple/requests/
解决方法：service docker restart
