Ian Wienand 6dce7ba605 ensure-pip: export ensure_pip_virtualenv_command
This makes ensure-pip export something that should be sensible for
users of pip: to put in their 'virtualenv_command' for their host.

The theory of operation is fairly simple; see if "python3 -m venv"
looks like it works, and set that as the command if it does.  If not,
set "virtualenv".  For sanity, we check if it works.

We pull in virtualenv in the Python 2 case, but for Python 3 we are
deliberately do not bring it as it is an unnecessary dependency.  If
jobs do require the actual `virtualenv` package, they should provision
it themselves ... except for Xenial, which, as described inline, has
issues.

Follow-on changes will convert existing zuul-jobs roles that install
tools into virtualenvs to use this argument.

Change-Id: Idad14c0e77eed5bf8df2c8f84f52fbdea2236a9f
2020-04-15 15:34:19 -07:00
..
2020-04-14 10:20:33 +10:00
2020-04-14 10:20:33 +10:00

Ensure pip is available

This role is intended install the requirements for the pip module on hosts.

Jobs that also wish to call pip via shell commands directly can also use this to ensure pip is available. However, it should be noted that calling pip is ambiguous when supporting many platforms. On some platforms it may install the package under the Python 2 interpreter and in others Python 3. You should use a qualified name (pip2 or pip3) to avoid confusion.

Role Variables