[wildfly-dev] Srcdeps in WildFly and WildFly Core

Thu Jan 26 11:28:06 EST 2017

On 2017-01-26 15:44, Brian Stansberry wrote:
> There’s been a lot of discussion overnight, but I’ll reply to this one directly since my answers better align with your questions here. :)
>
>> On Jan 26, 2017, at 2:54 AM, Peter Palaga <ppalaga at redhat.com> wrote:
>>
>> Hi Brian, thanks for your comments, more inline...
>>
>> On 2017-01-26 02:02, Brian Stansberry wrote:
>>> My only concerns with this would relate to comitting this kind of src
>>> dependency to the poms in the main branches in the widlfly/wildfly
>>> and wildfly/wildfly-core repos. We’ve managed to survive up to now
>>> with little or no need for that kind of thing, so until we get used
>>> to using this in other ways IMHO we should follow the KISS principle
>>> and forbid that.
>>
>> Maybe I overestimate the amount of changes that span over multiple git repos. Maybe you in the Core team do not do this often. But for us in the Sustaining Engineering Team, this is quite a typical situation. A substantial part of the reports from customers come with a description how to reproduce on the whole server, but they need to be fixed in a component. Having srcdeps would make the CP process simpler and faster, allowing us to uncover the conflicts and regressions earlier.
>
> I don’t see how merging to the main branches is required to get this benefit. Git topic branches are fully sharable and CI jobs against them are easily done. All CI tests of pull requests are tests of topic branches.

Yes, for me as the submitter of the PR, it is nice to get the feedback 
from the CI and a review early, even before the component is released, 
but it is quite bothersome to have to revisit the PR again once the 
component gets released and rebase (in case there there are conflicts) 
and either upgrade to the released component version or remove the 
upgrade change (if the upgrade was merged separately).

As long as my PR is not merged, my changes are not binding for the rest 
of the team. I want my PR to get merged as fast as possible and make 
others care that their changes are compatible with mine. I want to 
happily forget about the PR as soon as possible and pick a new task :)

> But, in any case perhaps you’ve seen clear need for merging to the main branches with the EAP CP branches. I haven’t seen it in WildFly / WildFly Core. I deliberately used specific repo names in my last comment to try and scope it. ;)

My reasons for merging there in EAP CP branches are the same as here in 
the community branches: it is better for PR submitters to merge as early 
as possible to avoid conflicts, subsequent PR edits and to keep the list 
of open tasks short.

> Note I’m not saying we should disallow PRs with src deps in the pom. We should just disallow merging until those are replaced.

Yes, I understand that and I appreciate that. That would be a progress too.

>>> A trick is avoiding doing that by mistake; i.e. a PR is sent up with
>>> a SRC dependency to get CI or review and accidentally gets merged.
>>
>> Oh, I am just realizing I have not said anything about merging. I actually do want to propose that commits with source dependencies get merged to e.g. wildfly-core master as early as possible. Those are the key points of Continuous Integration: get feedback quickly, and merge as soon as possible. This is exactly what Hawkular is doing since more than a year.
>
> We regularly produce releases (ideally weekly for WildFly Core), often at short notice under pressure.  Allowing merging of changes that are not acceptable for release increases the risk and effort required to do that, since now we have to scan for src deps and figure out how to get them out of the build. Perhaps needing assistance from whoever added the src dep and the lead of relevant component, both of whom are on the other side of the world asleep. (This is a real issue since we often do releases on Friday afternoon US time or Monday morning European time.) We already have too much risk and effort doing releases so adding more will need a really strong justification.

This sounds as a valid concern. I must admit I know little about how you 
plan and perform the releases of wildfly-core, wildfly and of the 
components in the community. Knowing how complex the graph of WF 
components is, I am far from underestimating any manual release efforts 
or efforts to setup a CI jobs to do that automagically. I'll have to 
gather more info about how you work.

>>> But I suppose that’s not the end of the world, so long as the release
>>> process will eventually detect it and fail.
>>
>> Yes, source dependencies on a stable branch do not harm. They just need to be avoided in releases (for which srcdeps offers technical means).
>
> They do do harm as they mean the branch is no longer releasable. It’s not end-of-the-world harm but it’s harm.

Well, I naivelly thought, that the components are obligated to provide a 
release, say, one day before a planned wildfly-core release and send a 
PRs that would then sweep out all source dependencies. And TBH, I did 
not think "releasable at any time" is important in wildfly-core. 
"Releasable once a week" still sounds good enough to me :)

>>> Can making srcdeps fail (or just disabling it) be turned on via a
>>> maven profile? With that we could set up such a profile and turn it
>>> on in CI jobs that are testing branches where it’s forbidden (e.g.
>>> the nightly builds of master.)
>>
>> Yes, the feature is called "failWith profiles" and can be configured in .mvn/srcdeps.yaml, like here in this srcdeps quickstart: https://github.com/srcdeps/srcdeps-maven/blob/master/srcdeps-maven-quickstarts/srcdeps-mvn-git-profile-quickstart/.mvn/srcdeps.yaml#L33
>> There is also "failWith properties" and "failWith goals". It is documented here: https://github.com/srcdeps/srcdeps-core/blob/master/doc/srcdeps.yaml#L130
>> By default there is failWith: {goals: release:prepare, release:perform}. Projects that do not use the release plugin can set e.g. failWith: {goals: deploy:deploy} or whatever else distinguishes their releases.
>>
>
> Thanks.
>
>>> Oh, one other concern — how robust is this in the face of poor
>>> maintenance? I see a lot of boilerplate in that .mvn/srcdeps.yaml.
>>
>> Which parts are boilerpate?
>
> All of it. :)
>
> I’m not using that word as an attack. I’m just saying it’s extra text that needs to be maintained, and since it’s separate from the usual place similar text occurs (the poms) it is more likely to diverge.

OK, now I know what you mean :) You are right that poms can diverge from 
srcdeps.yaml.

>>> If
>>> that gets out of date or something is the only effect that using a
>>> src dependency for the affected item doesn't work?
>>
>> Yes, I think so. As long as the .mvn/srcdeps.yaml file is syntactically correct, any misconfiguration there should not have any other effect than eventually breaking an embedded build.
>>
>> Generally, the things configured in .mvn/srcdeps.yaml tend to be quite stable - it is basically just mapping from GAVs to their respective git URLs. Git URLs do not change often. It is true that dependency artifacts come and go, but as long as their groupIds are selected reasonably (one groupId occurs in not more than one git repo) the mapping itself can be quite stable over time too.
>
> Yeah, that’s true. Where this file would be more likely to go unmaintained is adding new entries or cleaning out old ones. But the latter is just noise and if the only harm of the former is a srcdep can’t be used for that lib, then that will naturally get handled by whoever wants to use the srcdep.

Yes, exactly.

Thanks,

Peter

>>
>> Thanks,
>>
>> Peter
>>
>>>
>>>> On Jan 25, 2017, at 3:45 PM, Peter Palaga <ppalaga at redhat.com>
>>>> wrote:
>>>>
>>>> Hi *,
>>>>
>>>> this is not new to those of you who attended my talk on the F2F
>>>> 2016 in Brno. Let me explain the idea here again for all others who
>>>> did not have a chance to be there.
>>>>
>>>> Srcdeps [1] is a tool to build Maven dependencies from their
>>>> sources. With srcdeps, wildfly-core can depend on a specific commit
>>>> of, e.g., undertow:
>>>>
>>>> <version.io.undertow>1.4.8.Final-SRC-revision-aabbccd</version.io.undertow>
>>>>
>>>>
>>>>
>> where aabbccd is the git commit id to build when any undertow artifact
>>>> is requested during the build of wildfly-core.
>>>>
>>>> [1] describes in detail, how it works.
>>>>
>>>> The main advantage of srcdeps is that changes in components can be
>>>> integrated and tested in wildfly-core immediately after they are
>>>> committed to a public component branch. There is no need to wait
>>>> for the component release.
>>>>
>>>> Here in the WildFly family of projects, it is often the case that
>>>> something needs to be fixed in a component, but the verification
>>>> (using bug reproducer, or integration test) is possible only at the
>>>> level of wildfly or wildfly-core. Engineers typically work with
>>>> snapshots locally, but when their changes need to get shared (CI,
>>>> reviews) in a reproducible manner, snapshots cannot be used
>>>> anymore. In such situations a source dependency come in handy: it
>>>> is very easy to share and it is as reproducible as a Maven build
>>>> from a specific commit can be. All CIs and reviewers can work with
>>>> it, because all source dependency compilation is done under the
>>>> hood by Maven.
>>>>
>>>> Developers working on changes that span over multiple
>>>> interdependent git repos can thus get feedback (i-tests, reviews)
>>>> quickly without waiting for releases of components.
>>>>
>>>> Srcdeps emerged in the Hawkular family of projects to solve exactly
>>>> this kind of situation and is in use there since around October
>>>> 2015.
>>>>
>>>> When I said there is no need to wait for releases of components, I
>>>> did not mean that we can get rid of component releases altogether.
>>>> Clearly, we cannot, because i.a. for any tooling uninformed about
>>>> how srcdeps work, those source dependencies would simply be
>>>> non-resolvable from public Maven repositories. So, before releasing
>>>> the dependent component (such as wildfly-core) all its dependencies
>>>> need to be released. To enforce this, srcdeps is by default
>>>> configured to make the release fail, as long as there are source
>>>> dependencies.
>>>>
>>>> I have sent a PR introducing srcdeps to wildfly-core:
>>>> https://github.com/wildfly/wildfly-core/pull/2122 To get a feeling
>>>> how it works, checkout the branch, switch to e.g.
>>>> <version.io.undertow>1.4.8.Final-SRC-revision-1bff8c32f0eee986e83a7589ae95ebbc1d67d6bd</version.io.undertow>
>>>> (that happens to be the commit id of the 1.4.8.Final tag) and
>>>> build wildfly-core as usual with "mvn clean install". You'll see in
>>>> the build log that undertow is being cloned to
>>>> ~/.m2/srcdeps/io/undertow and that it is built there. After the
>>>> build, check that the
>>>> 1.4.8.Final-SRC-revision-1bff8c32f0eee986e83a7589ae95ebbc1d67d6bd
>>>> version of Undertow got installed to your local Maven repo (usually
>>>> ~/m2/repository/io/undertow/undertow-core )
>>>>
>>>> Are there any questions or comments?
>>>>
>>>> [1] https://github.com/srcdeps/srcdeps-maven#srcdeps-maven
>>>>
>>>> Thanks,
>>>>
>>>> Peter
>>>>
>>>> P.S.: I will be talking about srcdeps on Saturday 2017-01-28 at
>>>> 14:30 at DevConf Brno.
>>>> _______________________________________________ wildfly-dev mailing
>>>> list wildfly-dev at lists.jboss.org
>>>> https://lists.jboss.org/mailman/listinfo/wildfly-dev
>>>
>>
>