Proposal: Charm testing for 2.0

Thu Mar 17 09:38:43 UTC 2016

I tend to agree with Ryan, I think the ideas are reasonably sound, although
I'm not sure about the "every charm should be part of a bundle" policy, but
I certainly don't think you should discourage testing at charm level the
encapsulation can be useful, and you can never have too many tests!

I'm
+0.5 for charms part of a bundle expectation
-1 for discouraging charm tests

My 2 cents.

Tom

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On 17 March 2016 at 04:38, Ryan Beisner <ryan.beisner at canonical.com> wrote:

> Good evening,
>
> I really like the notion of a bundle possessing functional tests as an
> enhancement to test coverage.  I agree with almost all of those ideas.  :-)
>   tldr;  I would suggest that we consider bundle tests 'in addition to' and
> not 'as a replacement of' individual charm tests, because:
>
>
> *# Coverage and relevance*
> Any given charm may have many different modes of operation -- features
> which are enabled in some bundles but not in others.  A bundle test will
> likely only exercise that charm in the context of its configuration as it
> pertains to that bundle.  However, those who propose changes to the
> individual charm should know (via tests) if they've functionally broken the
> wider set of its knobs, bells and levers, which may be irrelevant to, or
> not testable in the bundle's amulet test due to its differing perspective.
> This opens potential functional test coverage gaps if we lean solely on the
> bundle for the test.
>
> There are numerous cases where a charm can shift personalities and use
> cases, but not always on-the-fly in an already-deployed model.  In those
> cases, it may take a completely different and new deployment topology and
> configuration (bundle) to be able to exercise the relevant functional
> tests.  Without integrated amulet tests within the charm, one would have to
> publish multiple bundles, each containing separate amulet tests.  For
> low-dev-velocity charms, for simple charms, or for charms that aren't
> likely to be involved in complex workloads, this may be manageable.  But I
> don't think we should discourage or stop looking for individual charm
> amulet tests even there.
>
> A charm's integrated amulet test can be both more focused and more
> expansive in what it exercises, as it can contain multiple deployment
> topologies and configurations (equivalent to cycling multiple unique
> bundles).  For example:  charm-xyz with and without SSL;  or in HA and
> without HA;  or IPv4 vs. IPv6; or IPv4 HA vs. IPv6 HA, multicast vs.
> unicast;  [IPv6 + HA + SSL] vs [IPv4 + HA + SSL]; or mysql deploying mysql
> proper vs. mysql deploying a variant;   and you can see the gist of the
> coverage explosion which translates to having a whole load of bundles to
> produce and maintain.
>
>
> *# Dev and test: cost, scale and velocity*
> Individual charm amulet tests are an important piece in testing large or
> complex models.  I'll share some bits of what we do for OpenStack charms as
> an example.  No bias.  :-)
>
> Each of the OpenStack charms contain amulet test definitions.  We lean
> heavily on those tests to deploy fractions of a full OpenStack bundle as
> the core of our CI development gate.  With [27 charms] x [stable + dev] x
> [8 Ubuntu/OpenStack Release Combos], there are currently* ~432 *possible
> variations of amulet tests (derived bundles of fractional OpenStacks).  A
> subset of those are executed in gate, depending on relevance to the
> developer's proposed change.  This allows us to endure a high velocity of
> focused testing on development in these very active charms.  Because the
> derived models are much smaller than the reference bundle, we can give
> developers rapid and automated feedback, plus they can iterate on
> development outside of our CI without having to be able to deploy a full
> OpenStack.
>
> That is not to say that we don't have acceptance and integration tests for
> full OpenStack bundles.  We do that in the form of mojo specs which
> dynamically deploy any number of full OpenStack bundle topologies and
> configurations against multiple Ubuntu+OpenStack release combos, using
> either the dev or the stable set of OpenStack charms.  It basically takes
> what I've described above for amulet and allows us to pivot entire bundles
> into different models automatically.  There are currently *84* such
> OpenStack mojo specs with tests (bundle equivalents)
>
> Fear not, this is mostly accomplished with bundle inheritance, yaml foo,
> and shared test libraries.  We're not actually maintaining ~*516 bundles*.
> But if we were to achieve the current level of coverage with bundles,
> that's approximately how many there would need to be.  This includes the
> upcoming Xenial and Mitaka releases.  Reduce by ~12% when Juno EOLs.  Add
> 12% when we hit Newton B1, and so on.
>
>
> *# How I'd like to use the proposed ideas*
> There are some OpenStack reference bundles in the charm store.  My
> suggested approach would be to continue to leverage individual charm amulet
> tests while adding functional tests to the existing charm store bundles.
> That would increase test coverage, and provide a mechanism to validate
> proposed changes to those specific bundles, such as to re-validate the
> bundles when charm versions are revved within them.
>
>
> To summarize, I am:
>
> -1 to stopping or discouraging individual charm amulet tests
>
> +1 for every charm containing amulet tests
>
> +1 for every charm containing unit tests
>
> +1 for every charm having amulet coverage in at least 1 bundle
>
> +1 for every bundle possessing amulet tests
>
>
> Also open to feedback, discussion, suggestions, kicks in the shin.
>
> Thanks for all the great tooling and thought leadership.  We leverage the
> everloving *stuff* out of Amulet.
>
> Charm on!
>
> --
> Ryan Beisner
> QA Engineer, Ubuntu OpenStack Engineering, Canonical, Ltd.
> irc:beisner  gh/gerrit:ryan-beisner  lp:~1chb1n
>
>
>
> On Wed, Mar 16, 2016 at 7:52 PM, Marco Ceppi <marco.ceppi at canonical.com>
> wrote:
>
>> Hello everyone!
>>
>> This is an email I've been meaning to write for a while, and have
>> rewritten a few times now. With 2.0 on the horizon and the charm ecosystem
>> rapidly growing, I couldn't keep the idea to myself any longer.
>>
>> # tl;dr:
>>
>> We should stop writing Amulet tests in charms and instead only write them
>> Bundles and force charms to do unit-testing (when possible) and promote
>> that all charms be included in bundles in the store.
>>
>> # Problem
>>
>> Without making this a novel, charm-testing and amulet started before
>> bundles were even a construct in Juju with a spec written before Juju 1.0.
>> Since then, many new comers to the ecosystem have remarked how odd it is to
>> be writing deployment validations at the charm level. Indeed, as years have
>> gone by and new tools have sprung up it's become clear that; having an
>> author try to model all the permutations of a charms deployment and do the
>> physical deploys at that charm level are tedious and incomplete at best.
>>
>> With the explosion of layers and improvements to uniting test in charms
>> at that component level, I feel that continuing to create these bespoke
>> "bundles" via amulet in a single charm will not be a robust solution going
>> forward. As we sprint closer to Juju 2.0 we're seeing a higher demand for
>> assurance of working scenarios, and a sharp focus on quality at every
>> level. As such I'd like to propose the following policy changes:
>>
>> - All bundles must have tests before promulgation to the store
>> - All charms need to have comprehensive tests (unit or amulet)
>> - All charms should be included in a bundle
>>
>> I'll break down my reasoning and examples in the following sections:
>>
>> # All bundles must have tests before promulgation to the store
>>
>> Writing bundle tests with Amulet is actually a more compelling story
>> today than writing an Amulet test case for a charm. As an example, there's
>> a new ELK stack bundle being produced, here's what the test for that bundle
>> looks like:
>> https://github.com/juju-solutions/bundle-elk-stack/blob/master/tests/10-test-bundle
>>
>> This makes a lot of sense because it's asserting that the bundle is
>> working as expected by the Author who put the bundle together. It's also
>> loading the bundle.yaml as the deployment spec meaning as the bundle
>> evolves the tests will make sure they continue to run as expected. Also,
>> this could potentially be used in future smoke tests for charms being
>> updated if a CI process swaps out, say elasticsearch, for a newer version
>> of a charm being reviewed. We can assert that both the unittests in
>> elasticsearch work and it operates properly in an existing real world
>> solution a la the bundle.
>>
>> Additional examples:
>> -
>> https://github.com/juju-solutions/bundle-realtime-syslog-analytics/blob/master/tests/01-bundle.py
>> -
>> https://github.com/juju-solutions/bundle-apache-core-batch-processing/blob/master/tests/01-bundle.py
>>
>> # All charms need to have comprehensive tests (unit or amulet)
>>
>> This is just a clarification and more strongly typed policy change that
>> require charms have (preferred) unit tests or, if not applicable, then an
>> Amulet test. Bash doesn't really allow for unittesting, so in those
>> scenarios, Amulet tests would function as a valid testing case.
>>
>> There are also some charms which will not make sense as a bundle. One
>> example is the recently promulgated Fiche charm:
>> http://bazaar.launchpad.net/~charmers/charms/trusty/fiche/trunk/view/head:/tests/10-deploy It's
>> a standalone pastebin, but it's an awesome service that provides deployment
>> validation with an Amulet test. The test stands up the charm, exercises
>> configuration, and validates the service responds in an expected way. For
>> scenarios where a charm does not have a bundle an Amulet test would be
>> required.
>>
>> Any charm that currently includes an Amulet test is welcome to continue
>> keeping such a test.
>>
>> # All charms should be included in a bundle
>>
>> This last one is to underscore that charms need to serve a purpose. This
>> policy is written as not an absolute, but instead a strongly worded
>> suggestion as there are always charms that are exceptions to the rules. One
>> such example is the aforementioned Fiche charm which as a bundle would not
>> make as much sense, but is still a purposeful charm.
>>
>> That being said, most users coming to consume Juju are looking to solve a
>> problem. Bundles underscore solutions to problems that people can consume,
>> and get started quicker.
>>
>> As such, when new applications are charmed a test of "is this application
>> something that serves a clear purpose" having a bundle submitted alongside
>> the charm validates that claim and provides users a way to immediately get
>> started with a solution.
>>
>> # Conclusion
>>
>> These policy changes, once accepted, will be targeted at all charms and
>> bundles in Xenial as well as any new charm submitted after policy
>> acceptance date for trusty, and finally any charm currently under review
>> will be encouraged to adhere to the new policy but won't be required.
>>
>> # Action items
>>
>> I'm seeking feedback on this concept and welcome suggestions for
>> improvements, questions, dissenting opinions, and any other remarks as well
>> as votes from ~charmers and feedback from the community at large.
>>
>> Thanks,
>> Marco Ceppi
>>
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>>
>
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