Noob question on environment / container OS

José Antonio Rey jose at
Wed Jul 16 05:21:38 UTC 2014

Hey Gaurav! Responding inline to each of the questions:

On 07/16/2014 12:12 AM, Gaurav Pandit 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)?

Correct. What Juju does on the cloud is launch a virtual machine or
cloud instance, in which it will deploy, configure and manage the service.

> 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")

You got this one too. All charms are ran under Ubuntu, which means
scripts need to be Ubuntu-compatible.

>   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?

Not exactly like that. When you propose a charm you specify the series.
At the current moment, both precise and trusty are open for submissions.
But if you want to have a package that is not in the Ubuntu repositories
for that series, yes, you can compile it, or add a PPA to get the
package from it.

> If this is mentioned somewhere in the documentation, please point me to it.

I don't believe this is stated in the documentation, no.

> (Overall, the documentation is pretty good!)

If there is anything else you need help with make sure to write, we'll
be totally happy to help! Thanks in advance for your interest in writing
Juju Charms, I believe you will find the experience quite enjoyable :)

> Thanks!
> Gaurav

José Antonio Rey

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