Welcome to GitLab!
Ara Adkins
me at ara.io
Thu Dec 27 12:04:10 UTC 2018
Congrats to Ben and everybody involved! This has been a long time coming and I’m super excited to see what it means for GHC in the future!
_ara
On 27 Dec 2018, at 11:56, Matthew Pickering <matthewtpickering at gmail.com> wrote:
>> To ensure that GHC's git history remains linear ghc/ghc will use GitLab's
>> "fast-forward without a merge commit" merge strategy.
>
> Are merge requests squashed before they are merged?
>
> It seems that the answer by default is no..
> https://gitlab.com/gitlab-org/gitlab-ce/issues/27956
>
> and the reason being that upsteam prefers "Convention over
> Configuration"..
> https://about.gitlab.com/handbook/product/#convention-over-configuration
>
> However it seems that there is a per-mr option which can be checked if
> you are diligent to do it for each MR. Some comments indicate that
> it's possible to implement a webhook to change this behaviour.
>
> Matt
>
>> On Thu, Dec 27, 2018 at 6:28 AM Ben Gamari <ben at well-typed.com> wrote:
>>
>> TL;DR. https://gitlab.haskell.org/ghc/ghc.git is now the official
>> upstream GHC repository. Various introductory notes are
>> discussed. Let me know if you have any trouble.
>>
>> Also, please do verify the correctness of the email address
>> associated with your Trac account in the next few weeks. It will
>> be used to map users when we transition Trac tickets to GitLab.
>>
>>
>>
>> Hello everyone,
>>
>> I am happy to announce that CI on GHC's GitLab instance [1] is now
>> stable. At this point https://gitlab.haskell.org/ghc/ghc.git is to be
>> considered the official upstream repository of GHC.
>>
>> The rest of this email is meant to serve as a brief introduction and
>> status update. It can also be viewed on the GitLab Wiki [2].
>>
>> [1] https://gitlab.haskell.org/
>> [2] https://gitlab.haskell.org/ghc/ghc/wikis/welcome
>>
>>
>> # Getting started
>>
>> To get started on GitLab you will first want to either create a new account
>> [1] or login with your GitHub credentials [2].
>>
>> Once you have an account you should add an SSH key [3] so that you can push
>> to your repositories. If you currently have commit rights to GHC notify me
>> (Ben Gamari) of your user name so I can grant you similar rights in GitLab.
>>
>>
>> [1] https://gitlab.haskell.org/users/sign_in
>> [2] https://gitlab.haskell.org/users/auth/github
>> [3] https://gitlab.haskell.org/profile/keys
>>
>>
>> # Updating your development environment
>>
>> You can updated existing working directory (assuming the usual upstream
>> remote name of `origin`) for the new upstream repository location by
>> running the following:
>>
>> git remote set-url origin https://gitlab.haskell.org/ghc/ghc.git
>> git remote set-url --push origin git at gitlab.haskell.org:ghc/ghc
>>
>> This is all that should be necessary; a quick `git pull origin master`
>> should verify that everything is working as expected.
>>
>>
>> # Continuous integration
>>
>> Continuous integration is now provided by GitLab's native continuous
>> integration infrastructure. We currently test a variety of
>> configurations, including many that neither Phabricator nor
>> CircleCI/Appveyor previously tested (see [1] for an example run):
>>
>> * With the make build system:
>> * x86_64/Linux on Fedora 27, Debian 8, and Debian 9
>> * i386/Linux on Debian 9
>> * aarch64/Linux on Debian 9 (currently broken due to a variety of
>> issues)
>> * x86_64/Windows
>> * x86_64/Darwin
>> * x86_64/Linux on Debian 9 in a few special configurations:
>> * unregisterised (still a bit fragile due to #16085)
>> * integer-simple
>> * building GHC with -fllvm
>> * With Hadrian:
>> * x86_64/Linux on Debian 9
>> * x86_64/Windows (currently broken due to #15950)
>>
>> We also run a slightly larger set of jobs on a nightly basis. Note that
>> binary distributions are saved from most builds and are available for
>> download for a few weeks (we may put in place a longer retention policy
>> for some builds in the future).
>>
>> There are admittedly a few kinks that we are still working out,
>> particularly in the case of Windows (specifically the long build times
>> seen on Windows). If you suspect you are seeing spurious build failures
>> do let us know.
>>
>> To make the best use of our limited computational resources our CI
>> builds occur in three stages:
>>
>> * lint: the style and correctness checkers which would previously be
>> run by `arc lint` and `git push`
>>
>> * build: Debian 9 Linux x86_64 built with make and Hadrian
>>
>> * full-build: the remaining configurations
>>
>> If a build fails at an earlier phase no further phases will be run.
>>
>>
>> [1] https://gitlab.haskell.org/ghc/ghc/pipelines/568
>>
>>
>> # Structuring your merge request
>>
>> With the transition to GitLab GHC is moving to a model similar to that
>> used by GitHub. If you have a Differential on Phabricator we will finish
>> review there. However, please post new patches as merge requests on
>> GitLab.
>>
>> Note that Phabricator and GitLab have quite different models for
>> handling patches. Under Phabricator a Differential is a single patch
>> with no further structure; larger changes can be composed of multiple
>> dependent Differentials.
>>
>> Under GitLab's model a merge request is a git branch consisting of
>> one or more patches. Larger changes can be handled in one of two ways:
>>
>> a. a set of dependent merge requests, each of which to be squashed when
>> merged.
>>
>> b. a single branch with each atomic change made in a single, buildable
>> commit
>>
>> Due to the difficulty of maintaining dependent merge requests, I would
>> recommend that contributors making larger changes use method (b).
>>
>>
>> # Submitting your merge request for review
>>
>> Depending upon whether you have push rights to the GHC repository there
>> are two ways to submit a merge request:
>>
>> * if you have push access you can push a branch directly to
>> git at gitlab.haskell.org:ghc/ghc.git and open merge request.
>>
>> In this case please do follow the usual branch naming conventions:
>>
>> * prefix all branch names with `wip/`
>>
>> * if you are fixing a particular ticket consider using the name
>> `wip/TNNNN`
>>
>> * if not you can create a fork using the "Fork" button on the project
>> page [1] and push your branch there
>>
>> In either case after you have pushed your branch open a merge request
>> against ghc/ghc [2].
>>
>> [1] https://gitlab.haskell.org/ghc/ghc/forks/new
>> [2] https://gitlab.haskell.org/ghc/ghc/merge_requests/new
>>
>>
>> # Reviewing and merging merge requests
>>
>> As always, all contributors are encouraged to help review proposed
>> changes. If you are unfamiliar with GitLab's review interface please see
>> GitLab's user documentation [1]. Here are a few quick highlights for
>> those who are familiar with GitHub but haven't yet used GitLab:
>>
>> * As with GitHub, GitLab supports both inline and out-of-line comments.
>>
>> * Comments that are actionable (known as "discussions") can be marked
>> as resolved and collapsed.
>>
>> * Comments can be left on both changed and unchanged lines
>>
>> * Revisions of a merge request can be viewed and compared using the
>> two drop-down menus at the top of the Changes tab
>>
>> * Merge requests can require approvals from particular users before
>> considered as mergable
>>
>> * Merge requests can be placed in "merge when CI passes" state, which
>> will cause merge requests to be merged as soon as they are green
>>
>> From this point onward all changes to GHC will be merged via
>> GitLab's merge requests facility and must pass CI before being merged.
>> To ensure that GHC's git history remains linear ghc/ghc will use GitLab's
>> "fast-forward without a merge commit" merge strategy. Consequently you
>> will be asked to rebase merge requests which are not fast-forward merges
>> before merging (a convenient "Rebase" button will appear if the rebase
>> can be carried out without conflicts.
>>
>> [1] https://gitlab.com/help/user/discussions/index.md#discussions
>>
>>
>> # Status of the Trac migration
>>
>> Tobias will be continuing work on the Trac ticket migration after a bit
>> of a holiday break. Hopefully by mid-January we will be able to move
>> forward on this part of the migration; I will share more details about
>> this as they develop.
>>
>> In the meantime, users of Trac should check and possibly update the
>> email address associated with their account [1]. This address will be
>> used to correlate Trac users with their GitLab equivalents so the
>> correctness of this address will be important in preserving attribution
>> information during the Trac import.
>>
>> [1] https://ghc.haskell.org/trac/ghc/prefs
>>
>>
>> # Next steps
>>
>> We are actively working on cleaning up a few remaining issues with CI:
>>
>> * build times are still very long on Windows, despite the fact that we
>> are only building the `quick` build flavour on that platform;
>> consequently GitLab CI Windows builds do sometimes timeout
>> when we are faced with long build queues.
>>
>> * we at times run low on disk space on our Windows builder runners,
>> resulting in occasional spurious build failures
>>
>> * Appveyor builds (which are supposed to supplement the native GitLab
>> builds) rarely seem to finish
>>
>> GitLab upstream has been incredibly supportive of our transition effort
>> and has expressed interest in assisting us with issues that we
>> encounter. Our current requests can be found on our migration effort's
>> tracking ticket [1]. If you find any additional bugs or workflows that
>> could be improved please do let me know and I can raise the matter with
>> GitLab.
>>
>> [1] https://gitlab.com/gitlab-org/gitlab-ce/issues/55039
>>
>>
>> # Acknowledgments
>>
>> I would like to acknowledge several parties for their contributions to
>> this effort:
>>
>> * Packet.net and Google X for their generous donation of hosting for
>> continuous integration and web hosting
>>
>> * GitLab and their Open Source program for many productive discussions,
>> their generous support, and the GitLab Ultimate license used by
>> gitlab.haskell.org.
>>
>> * Davean Scies for his help procuring the hosting services that power
>> our continuous integration.
>>
>> * Tweag.io for their offer of help and advice
>>
>> * Matthew Pickering, Alp Mestangullari, Tobias Dammers for their work
>> in setting up the new instance, sorting out the details of the
>> migration, and debugging problems when they arose
>>
>> Finally, thanks to GHC's contributors for their patience during this
>> transition; it has been a long process which has stolen a significant
>> amount of attention from other matters. My apologies we have been a bit
>> less responsive than usual in code review and ticket triage over the
>> past month or two. Regardless, I am hopeful that this wait will be
>> worthwhile.
>>
>>
>> # Final thoughts
>>
>> This is not only a milestone for the GitLab migration but also for GHC
>> itself. For the first time GHC has fully-automated testing, proposed
>> patch CI, and release generation across the full range of Tier 1
>> configurations it supports, with passing builds in all cases.
>>
>> We are very excited to begin this next chapter of GHC's development and
>> are looking forward to your feedback on how we can further improve our
>> new infrastructure. Onward and upwards!
>>
>> Cheers,
>>
>> - Ben
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