Charm series in bundles (Was Re: Juju 2.0 and local charm deployment)

[Ian Booth]

One additional enhancement we need for bundles concerns specifying series for
multi-series charms, in particular local charms now that the local repo will be
going away.

Consider:

A new multi-series charm may have a URL which does not specify the series. In
that case, the series used will be the default specified in the charm metadata
or the latest LTS. But we want to allow people to choose their own series also.

So we need a new (optional) Series attribute in the bundle metadata.

bundle.yaml
  series: trusty
  services:
    nova-compute:
      series: xenial <------ new
      charm: ./nova-compute
      num_units: 2

or with a charm store charm

bundle.yaml
  series: trusty
  services:
    nova-compute:
      series: xenial    <------ new
      charm: cs:nova-compute
      num_units: 2


Note: the global series in the bundle still applies if series is not otherwise
known.
The new series attribute is per charm.

So in the case above, cs:nova-compute may ordinarily be deployed on trusty (the
default series in that charm's metadata). But the bundle requires the xenial
version. With the charm store URL, we can currently use cs:xenial/nova-compute
but that's not the case for local charms deployed out of a directory. We need a
way to allow the series to be specified in that latter case.

We'll look to make the changes in core initially and can followup later with the
GUI etc. The attribute is optional and only really affects bundles with local
charms.



On 09/03/16 09:53, Ian Booth wrote:
> So to clarify what we'll do. We'll support the same syntax in bundle files as we
> do for deploy.
> 
> Deploys charm store charms:
> 
> $ juju deploy cs:wordpress
> $ juju deploy wordpress
> 
> Deploys a local charm from a directory:
> 
> $ juju deploy ./charms/wordpress
> $ juju deploy ./wordpress
> 
> So below deploys a local nova-compute charm in a directory co-located with the
> bundle.yaml file.
> 
>  series: trusty
>  services:
>    nova-compute:
>      charm: ./nova-compute
>      num_units: 2
> 
> This one deploys a charm store charm:
> 
>  series: trusty
>  services:
>    nova-compute:
>    charm: nova-compute
>    num_units: 2
> 
> 
> 
> On 09/03/16 03:59, Rick Harding wrote:
>> Long term we want to have a pattern when the bundle is a directory with
>> local charms in a directory next to the bundles.yaml file. We could not do
>> this cleanly before the multi-series charms that are just getting out the
>> door. I think that bundles with local charms will be suboptimal until we
>> can get those bits to line up.
>>
>> I don't think we want to be doing the file based urls, but to build a
>> pattern that's reusable and makes sense across systems. Creating a standard
>> pattern I think is the best path forward.
>>
>> On Tue, Mar 8, 2016 at 12:26 PM Martin Packman <martin.packman at canonical.com>
>> wrote:
>>
>>> On 05/03/2016, Ian Booth <ian.booth at canonical.com> wrote:
>>>>>
>>>>> How will bundles work which reference local charms? Will this work as
>>>>> expected where nova-compute is a directory at the same level as a bundle
>>>>> file?
>>>>>
>>>>> ```
>>>>> series: trusty
>>>>> services:
>>>>>   nova-compute:
>>>>>     charm: ./nova-compute
>>>>>     num_units: 2
>>>>> ```
>>>>>
>>>>
>>>> The above will work but not until a tweak is made to bundle deployment to
>>>> interpret a path on disk rather than a url. It's a small change. This
>>> would
>>>> be done as part of the work to remove the local repo support.
>>>
>>> Can we keep interpreting the the reference in the bundle as a url, but
>>> start supporting file urls? That seems neater than treating the cs:
>>> prefix as magic not-a-filename.
>>>
>>> The catch is that there's no sane way of referencing locations outside
>>> a base url.
>>>
>>>     charm: file:nova-compute
>>>
>>> Works as a reference to a dir inside the base location, but:
>>>
>>>     charm: file:../nova-compute
>>>
>>> Will not work as a reference to a sibling directory. And absolute file
>>> paths are pretty useless across machines.
>>>
>>> Martin
>>>
>>> --
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>>>
>>
>>
>>