Merge lp:~vila/uci-engine/update-doc-lxc into lp:uci-engine

[Vincent Ladeuil]

Update lxc doc about precise deployments and cloud-archive:icehouse apt source

My local deployments started failing for the rabbit workers with a non-sensical:

Traceback (most recent call last):
  File "./test_runner/tstrun/run_worker.py", line 28, in <module>
    from tstrun import (
  File "/srv/ci-airline-tr-rabbit-worker/code/r839_3cc7fe689dd554940efeeac2f23c08a60b77aad4/test_runner/tstrun/testbed.py", line 26, in <module>
    from novaclient import (
  File "/usr/lib/python2.7/dist-packages/novaclient/client.py", line 34, in <module>
    from six.moves.urllib import parse
ImportError: No module named urllib

The root cause was that the charm does (paraphrasing ;):

# add-apt-repository -y cloud-archive:icehouse
# apt-get install python-novaclient

and this doesn't upgrade python-six.

This happens only in local lxc deployments with a hacked
juju-precise-template (so tarmac is immune).

[Evan (ev)]

Can you elaborate a bit further on what is going on? If python-novaclient needs a later version of python-six than what's specified in debian/control, then that's a bug in the python-novaclient packaging that we should at least file a bug for, if not fix outright.

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review: Approve (continuous-integration)

[Vincent Ladeuil (vila)]

> Can you elaborate a bit further on what is going on? If python-novaclient
> needs a later version of python-six than what's specified in debian/control,
> then that's a bug in the python-novaclient packaging that we should at least
> file a bug for, if not fix outright.

No, python-novaclient depends on python-six (any version).

As pitti explained to me (I'm a packaging noob ;) apt-get install does the minimal amount of work and just install the newest python-novaclient which only requires python-six (any version).

In the general case, you never install a package without doing apt-get update first or if you do, you know what you're doing.

Here, we run into a weird corner case which could be fixed by forcing apt-get update in the charm but that seems overkill since the only bogus setup is the hack we use for the juju lxc template.

[Evan (ev)]

Does python-novaclient depend on features in python-six that are only available in a specific version of python-six? If so, the solution is to put a versioned dependency on python-six in the python-novaclient packaging. For example:

Depends: python-six (>= 1.5.2-0)

[Vincent Ladeuil (vila)]

> Does python-novaclient depend on features in python-six that are only
> available in a specific version of python-six? If so, the solution is to put a
> versioned dependency on python-six in the python-novaclient packaging. For
> example:
>
> Depends: python-six (>= 1.5.2-0)

Right. The problem as I see it is that I only discovered a source of potential issues: in this case, we stopped using the python-novaclient package from the phase-0 PPA to use the icehouse one.

So fixing this by adding the version to the python-six package, while being the *correct* fix, is quite involved (do we take ownership of this package to put a fixed version into our PPA again or do we propose that fix upstream (after checking it makes sense for them, I can perfectly understand them if they prefer to *not* pin their dep, they don't have the same constraints as us ?)).

Both are quite out of scope for this docfix proposal though ;)

I would rather spend time purging our ppa from deps we don't care about anymore.

[Evan (ev)]

Huh? This isn't about pinning dependencies. Packages must be functional at install time without needing an apt-get upgrade.

If parts of python-novaclient do not function with older versions of python-six, *that is a bug.* It's not specific to us. In fact, the version in utopic already has the fix:

python-six (>= 1.7.0)

So we could experiment with using the utopic version in our PPA, or ask the Server Team to pull the fix from utopic to the icehouse cloud archive with us then PPA-copying it over.

[Vincent Ladeuil (vila)]

> Huh? This isn't about pinning dependencies. Packages must be functional at
> install time without needing an apt-get upgrade.
>
> If parts of python-novaclient do not function with older versions of python-
> six, *that is a bug.* It's not specific to us. In fact, the version in utopic
> already has the fix:
>
> python-six (>= 1.7.0)
>
> So we could experiment with using the utopic version in our PPA, or ask the
> Server Team to pull the fix from utopic to the icehouse cloud archive with us
> then PPA-copying it over.

Ok, summarizing again: I'm not denying there is a potential bug, I ran into it. But it seems that a broken setup leave me with some inconsistent archives and I know wonder whether someone can even reproduce it (the rabbitmq-worker should do the right thing). In any case, I've filed https://app.asana.com/0/8309126707866/17625138719505 to continue this discussion.

But that shouldn't block *this* MP which document the use of the icehouse cloud archive in the lxc template.

[Evan (ev)]

review: Approve

=== modified file 'docs/using-lxc-for-local-development.rst'
--- docs/using-lxc-for-local-development.rst	2014-09-18 14:14:15 +0000
+++ docs/using-lxc-for-local-development.rst	2014-10-09 09:59:14 +0000
@@ -104,6 +104,20 @@
     sudo lxc-stop --name juju-trusty-template
 
 
+Alternatively for a precise deployment you want:
+
+.. code-block:: none
+
+    # You'll now have an lxc container named juju-precise-template.     
+    # Modify it with these commands:
+    sudo lxc-start -d --name juju-precise-template
+    sudo lxc-attach --name juju-precise-template -- add-apt-repository -y ppa:canonical-ci-engineering/ci-airline-phase-0
+    sudo lxc-attach --name juju-precise-template -- add-apt-repository -y cloud-archive:icehouse
+    sudo lxc-attach --name juju-precise-template -- apt-get update
+    sudo lxc-attach --name juju-precise-template -- apt-get install -y rabbitmq-server python-amqplib python-pip python-jinja2 mercurial git-core subversion bzr gettext python-django-south python-lazr.enum python-tastypie python-amqplib python-swiftclient postgresql-9.1 postgresql-contrib-9.1 python-psutil dput python-dput lazr.enum python-tz python-gnupg qemu-utils python-glanceclient python-amqplib python-requests python-novaclient python-psycopg2 pwgen postgresql-client gunicorn python-support pgtune postgresql-9.1-debversion postgresql-plpython-9.1 python-dnspython
+
+    sudo lxc-stop --name juju-precise-template
+
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