Package updates and charm responsibilities

[John Meinel]

I'm pretty sure if you "apt-get install foo" and there is a newer foo, it
will upgrade it. However, I don't think it upgrades the chain of
dependencies, unless maybe if there are declared conflicts? I've certainly
tried out the "how do I upgrade one package" and "apt-get install" was the
answer I found.

John
=:->



On Thu, Apr 10, 2014 at 5:45 PM, Mark Shuttleworth <mark at ubuntu.com> wrote:

> On 10/04/14 12:00, Stuart Bishop wrote:
> > On 10 April 2014 17:42, John Meinel <john at arbash-meinel.com> wrote:
> >> All hooks are run sequentially (we explicitly take out a lock across all
> >> hooks that want to run on a machine), just so that charms can do
> whatever
> >> they want with apt without stepping on each other's toes.
> >>
> >> I would think "install" is the most likely hook to actually do update
> and
> >> install. I'm not sure about a charm ever doing "upgrade" since that
> would
> >> upgrade other packages, right?
> > Right. I'm wondering if that is the responsibility of the charm, or of
> > other management systems like Landscape or configuring unattended
> > security updates.
> >
> > At the moment I do have a charm that does an upgrade, and it does
> > upgrade everything. I suspect I should remove that line.
>
> Yes, I would suggest that charms should focus on their specific
> workload, not the system as a whole.
>
> That said, there can be bad results if, for example, the package listing
> is out of date. If you try to apt-get a package, and the package listing
> is way out of date, you'll be told the package cannot be found (because
> newer versions have replaced it in the archive). Updating the package
> *listing* is non-destructive, so an "apt-get update" is perfectly
> reasonable. After that, a charm can "apt-get install foo" and know it
> will get the current version.
>
> >> There isn't a process in juju today that does regular "keep my machines
> up
> >> to date" but you do have "juju run sudo apt-get update" if you want to
> do it
> >> manually.
> > There is 'upgrade-charm'. I could argue that upgrade-charm should do a
> > full update, so the new version of the charm is running with all the
> > dependencies it was tested with. But I can argue the other way too :D
>
> Is it possible to use APT to upgrade just a single piece of software and
> its dependencies? If so, that would be appropriate, yes.
>
> Mark
>
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