[PATCH 3 of 3] docs/installation: clarify root privileges requirement for 'pip install'

[Thomas De Schampheleire]

Hi,

On Sun, Mar 15, 2015 at 2:06 PM, Mads Kiilerich <mads at kiilerich.com> wrote:
> On 03/15/2015 01:04 PM, Andrew Shadura wrote:
>>
>> Hello,
>>
>> On Sat, 14 Mar 2015 23:03:27 +0100
>> Mads Kiilerich <mads at kiilerich.com> wrote:
>>
>>>> +Note that this method requires root privileges. When installing as
>>>> a regular +user, you can use::
>>>> +
>>>> +    pip install --user kallithea
>>>> +
>>>> +or (recommended) install Kallithea in a virtualenv (next section).
>>>
>>> I think we should give a different advice.
>>>
>>> In my opinion, pip should only be used inside a virtualenv. Running
>>> it as root is wrong.
>>>
>>> I don't know this --user option. How does it work ... if it does work?
>>
>> It really does work, it installs packages into ~/.local, which is
>> useful if you just want to test things out, and if you do want to mix
>> your system packages with locally installed ones.
>
>
> How does it work? Will the global installation of pip hook into Python
> startup and inject packages from .local in sys.path? How about executable
> scripts - where are they placed?
>
> Either way, I understand that pip --user still will install the packages in
> a shared location. That will make it very hard to uninstall or "start over".
> I guess it also makes it impossible for the a user to have more than one
> Kallithea instance.
>
> I think we need more clarification of pros and cons of the different options
> before we start recommending more options.
>
> In my opinion, virtualenv is the only _real_ option. It makes pip simple and
> managable so we know exactly where the dependencies for this app is
> installed. Running pip without virtualenv (with or without --user) can
> easily create situations that are very hard to recover from.

I added this option as it came up on IRC (Andrew suggested it), but
wouldn't mind removing it again.

Let's add a paragraph in the beginning briefly describing the options
with pros/cons as Mads suggested, and then discuss the virtualenv
solution first and the standard pip second. With this order, we can
leave the --user suggestion; the cons would have to be clear from the
intro paragraph.

What do you think?

Best regards,
Thomas