Installing without an internet connection erroneous reports requirements are up to date

• Pip version: 9.0.1
• Python version: 3.5
• Operating system: Fedora 25

Description:

Installing without an internet connection gives erroneous output.

Specifically after attempting to fetch some information from the net, it will report that a requirement is up to date. I had pytest-2.9.2 installed, and without internet it shows

Requirement already up-to-date: pytest in /usr/lib/python3.5/site-packages

With internet, it upgrades to pytest-3.0.6.

What I’ve run:

$ python3 -m pip install -U pytest
Retrying (Retry(total=4, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f77960b9cc0>: Failed to establish a new connection: [Errno -2] Name or service not known',)': /simple/pytest/
Retrying (Retry(total=3, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f779605a128>: Failed to establish a new connection: [Errno -2] Name or service not known',)': /simple/pytest/
Retrying (Retry(total=2, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f779508e4e0>: Failed to establish a new connection: [Errno -2] Name or service not known',)': /simple/pytest/
Retrying (Retry(total=1, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f779507d6d8>: Failed to establish a new connection: [Errno -2] Name or service not known',)': /simple/pytest/
Retrying (Retry(total=0, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f779507d828>: Failed to establish a new connection: [Errno -2] Name or service not known',)': /simple/pytest/
Requirement already up-to-date: pytest in /usr/lib/python3.5/site-packages
Retrying (Retry(total=4, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f7795031f98>: Failed to establish a new connection: [Errno -2] Name or service not known',)': /simple/py/
Retrying (Retry(total=3, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f7795031e48>: Failed to establish a new connection: [Errno -2] Name or service not known',)': /simple/py/
Retrying (Retry(total=2, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f7795038080>: Failed to establish a new connection: [Errno -2] Name or service not known',)': /simple/py/
Retrying (Retry(total=1, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f7795038128>: Failed to establish a new connection: [Errno -2] Name or service not known',)': /simple/py/
Retrying (Retry(total=0, connect=None, read=None, redirect=None)) after connection broken by 'NewConnectionError('<pip._vendor.requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0x7f7795038208>: Failed to establish a new connection: [Errno -2] Name or service not known',)': /simple/py/
Requirement already up-to-date: py>=1.4.29 in /usr/lib/python3.5/site-packages (from pytest)

Then with an internet connection,

$ sudo python3 -m pip install -U pytest
[sudo] password for jayvdb: 
Collecting pytest
  Downloading pytest-3.0.6-py2.py3-none-any.whl (172kB)
    100% |████████████████████████████████| 174kB 612kB/s 
Collecting setuptools (from pytest)
  Downloading setuptools-34.1.1-py2.py3-none-any.whl (389kB)
    100% |████████████████████████████████| 399kB 624kB/s 
Requirement already up-to-date: py>=1.4.29 in /usr/lib/python3.5/site-packages (from pytest)
Requirement already up-to-date: six>=1.6.0 in /usr/lib/python3.5/site-packages (from setuptools->pytest)
Requirement already up-to-date: packaging>=16.8 in /usr/lib/python3.5/site-packages (from setuptools->pytest)
Requirement already up-to-date: appdirs>=1.4.0 in /usr/lib/python3.5/site-packages (from setuptools->pytest)
Requirement already up-to-date: pyparsing in /usr/lib/python3.5/site-packages (from packaging>=16.8->setuptools->pytest)
Installing collected packages: setuptools, pytest
  Found existing installation: setuptools 27.1.2
    Uninstalling setuptools-27.1.2:
      Successfully uninstalled setuptools-27.1.2
  Found existing installation: pytest 2.9.2
    Uninstalling pytest-2.9.2:
      Successfully uninstalled pytest-2.9.2
Successfully installed pytest-3.0.6 setuptools-34.1.1

[jayvdb]

I don’t have any custom repositories setup. Only the cache. pip should give a non-zero exit status and an appropriate failure message, even “No repositories could be reached” would be better.

[chrahunt]

How would this look in the following situations:

1. Multiple repositories are configured and only some of them are unreachable
2. No repositories are reachable but --find-links was provided on the command-line
3. Same as the above two, but the currently-installed requirement does not have any available versions present

I could see reasonable use cases for the above that would all want different behavior, especially with respect to return code since it would be relevant to CI or any automation.

I think the best we could do here without being on the hook to make things complex later is to add an explicit warning when we’re giving up on an index:

Giving up on index <url>, due to <last error>

That easy enough to grep, so enforcement that a repo is accessible in CI (for users that don’t want to pin versions) should be straightforward.