Do not land code on blocked branches

[Ian Booth]

My email was poorly worded, sorry. It's main purpose was to reply the the email
from QA to let the QA folks know that an incompatibility was discovered which
explains the CI test failures holding up the 1.24 release, and that a solution
was in progress.

John's analysis is correct. I am almost done restoring the Juju 1.16 behaviour
to reinstate compatibility with quickstart as it stands today. Any quickstart
changes are not urgent therefore. The root cause is that Juju 1.16 behaviour was
removed and even though Juju clients are fine with this, existing external
clients may inadvertently be relying on such deprecated behaviour.

The difficulty is that right up until 1.18, the first point from which we were
required to retain backwards compatibility "forever", quite a lot of
functionality was deprecated. It's hard to know which external (non Juju)
clients depend on such behaviour. That's why we have CI tests for the important
clients like quickstart and deployer. So in this case, the CI tests have done
their job :-)

On 03/05/15 22:11, John Meinel wrote:
> Just going off the bits that Ian pointed to, the section of code was if you
> called ServiceDeploy with a CharmStore URL (eg cs:mysql) but you had not
> already called AddCharm.
> 
> The "juju" cli client already knows to call Client.AddCharm with the given
> URL, whereas the internal api/client/client.go does a double check if it
> gets called with a charm URL that isn't already in state.
> 
> Now, I don't know how Quickstart would be triggering
> apiserver/client/client.go
> The error here: in traceback looks like:
> connecting to wss://
> 52.6.157.186:17070/environment/47724da5-9b38-4141-8f92-03d8f4225de9/api
> environment type: ec2
> bootstrap node series: trusty
> charm URL: cs:trusty/juju-gui-27
> requesting juju-gui deployment
> juju-quickstart: error: bad API response: charm "cs:trusty/juju-gui-27" not
> found
> 2015-05-01 18:28:59 ERROR Command '('juju', '--show-log', 'quickstart',
> '-e', 'aws-quickstart-bundle', '--constraints', 'mem=2G', '--no-browser',
> '/var/lib/jenkins/repository/landscape-scalable.yaml')' returned non-zero
> exit status 1
> Traceback (most recent call last):
>   File "/var/lib/jenkins/juju-ci-tools/quickstart_deploy.py", line 51, in
> run
>     for step in self.iter_steps():
>   File "/var/lib/jenkins/juju-ci-tools/quickstart_deploy.py", line 70, in
> iter_steps
>     self.client.quickstart(self.bundle_path)
>   File "/mnt/jenkinshome/juju-ci-tools/jujupy.py", line 335, in quickstart
>     self.juju('quickstart', args, self.env.needs_sudo())
>   File "/mnt/jenkinshome/juju-ci-tools/jujupy.py", line 294, in juju
>     return subprocess.check_call(args, env=env)
>   File "/usr/lib/python2.7/subprocess.py", line 511, in check_call
>     raise CalledProcessError(retcode, cmd)
> 
> 
> So it would appear that we had code to allow users to call
> Client.ServiceDeploy(cs:mysql) and the server would lookup the charm and
> deploy it for the user, but we stopped doing that as a Juju CLI since 1.16.
> 
> However, I think this is *our* bad because this is a very important client
> (quickstart and probably others) that has been relying on this behavior in
> all our recent releases.
> 
> Compat with juju-cli != compatibility with Juju API users.
> 
> AFAIK we don't have a great way to respond to clients that behavior is
> deprecated, but we can bump the Version of the API and change the behavior.
> We definitely should have done that here rather than just remove the
> behavior.
> 
> John
> =:->
> 
> On Sun, May 3, 2015 at 3:59 PM, Richard Harding <rick.harding at canonical.com>
> wrote:
> 
>> On Sun, 03 May 2015, Ian Booth wrote:
>>
>>>>
>>>> Curtis has filed three new bugs for these so far, and there appears to
>>>> be one or two more to come:
>>>>
>>>> <https://bugs.launchpad.net/juju-core/+bug/1450912>
>>>
>>> The issue here is that quickstart is relying on Juju 1.16 behaviour.
>> There was a
>>> block of code with a comment:
>>>
>>> // Remove this whole if block when 1.16 compatibility is dropped.
>>>
>>> The code block was removed because 1.18 was our minimum compatibility
>> version.
>>> But it seems we have to restore the 1.16 behaviour. Note that this is
>> not an
>>> upgraded environment where we need to retain compatibility with older
>>> deployments. It is a fresh 1.24 install which should be able to rely on
>> 1.18 and
>>> later behaviour only.
>>
>> Ian, can you be more specific on the chunk of code that was removed or
>> branch I can look at for this? I'll happily file a bug and update
>> quickstart, we just need to know what's changed there. Having a branch in
>> hand or a bug will assist us in getting that updated as fast as possible.
>>
>> In searching through the quickstart code there's no hard requirement or
>> notes on 1.16.
>>
>> Thanks
>>
>> --
>>
>> Rick Harding
>>
>> Juju UI Engineering
>> https://launchpad.net/~rharding
>> @mitechie
>>
>> --
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>>
>