Problem in step 3 of build: Failed to establish a new connection

[MSTechKnow]

Getting connection failure in 'RUN pip install --upgrade pip'

Retrying (Retry(total=4, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f35053cfb00>: Failed to establish a new connection: [Errno -2] Name or service not known',)': /simple/pip/
Retrying (Retry(total=3, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f35053cfe10>: Failed to establish a new connection: [Errno -2] Name or service not known',)': /simple/pip/
Retrying (Retry(total=2, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f35053cfef0>: Failed to establish a new connection: [Errno -2] Name or service not known',)': /simple/pip/
Retrying (Retry(total=1, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f35053cffd0>: Failed to establish a new connection: [Errno -2] Name or service not known',)': /simple/pip/

[dmtucker]

@MSTechKnow Are you running on a Ubuntu machine or some other OS with resolvconf? I have hit a very similar issue (on a completely unrelated project), and the culprit seems to be that resolvconf puts the loopback address as the only nameserver in /etc/resolv.conf.