Noob question on environment / container OS

[David Cheney]

Hi Gaurav,

On Wed, Jul 16, 2014 at 3:12 PM, Gaurav Pandit <pandit.gaurav at gmail.com> wrote:
> I have just started reading Juju documentation and playing with local
> environment with default environment.
>
> Before I get too far (writing charms and such), I want to confirm my
> understanding of some basics:
>
> 1. Is it correct to say that each machine created by juju in the environment
> is basically an Ubuntu OS (most likely 14.04)?

Yes. The series of the ubuntu machine will match the series of the
charm deployed.

> 2. If that's the case, then
>   a. Does it mean that the commands executed in hooks, say, a basic bash
> script that installs a particular software package, needs to be compatible
> with Ubuntu OS? (e.g. use of "apt-get" and not "yum")

yes

>   b. It could be challenging to install older version of any package (say
> Apache 2.2 series) that is not available in 14.04 repository. In such cases,
> instead of "apt-get install", it will have to be compiled and built after
> downloading the source code, and the dependencies need to be resolved
> manually too - is this correct?

yes, but it sounds like you're pushing in the wrong direction. Charms
are expected to represent the best practice for deploying a service.
Sometimes a service can be obvious, ie, postgres, but other times it
can be a little more complicated, say if you are writing a charm for
deploying your django application, which will most likely require
setting up gunicorn and nginx or apache on each of the service units.

I guess what I am saying is compiling something from source would be
dubious best practice, we certainly encourage people writing charms to
consume packages from the main LTS distributions themselves, and if
that is not sufficient, using a PPA.

>
> If this is mentioned somewhere in the documentation, please point me to it.
>
> (Overall, the documentation is pretty good!)
>
> Thanks!
> Gaurav
>
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