Re: [eigen] Bitbucket is dropping its Mercurial support!

[ Thread Index | Date Index | More lists.tuxfamily.org/eigen Archives ] 

Hello!

Let me chip in here.
A good git import tool would put the mercurial hashes into the commit messages, so there is at least any chance of finding them.
Our company uses a self hosted GitLab instance with these premium and we had a blast. We still have a seperate issue management from gitlab, and it just integrates with gitlab reasonably well.
Regarding gitlab CI: we don't use gitlab runner much. Gitlab EE provides integration with Jenkins buildnodes and I'm sure other CI like travis work as well.
So we have a mix, some nighly builds or on push builds int he gilab runner, some CI in the runner, some CI in Jenkins, some nightly jobs in Jenkins, mixed pipelines, some on VMs, some running natively, and it all works well. So this shouldn't be a concern with gitlab. Also gitlab can automatically serve mirrors on github or elsewhere if they are wanted (and nightly CI can then run from there)
Moving to git would also allow us to subtree in Eigen into our codebase, and to subtree pull and split, instead of copying around without any history on each release... 


Just my 2 cents,

Martin


Am 24.08.19 um 16:05 schrieb Christoph Hertzberg:

Hi!

On 24/08/2019 12.30, David Tellenbach wrote:

just some thoughts about some points you've made:
b) Fixing internal links inside commit messages ("grafted from ...", "fixes error introduced in commit ...") 
Maybe I've forgot something crucial but doing something like

for branch in $(hg branches | awk '{print $1}'); do
     hg update -C  $branch > /dev/null
     echo "$branch $(hg log -v | egrep "bitbucket.org" | wc -l)"
done

gives me

Branch                       Links
------                       ------
default                      9
[...]
The point you missed is that especially the "grafted from" links do not include the full URL, just the hg-hash (which is different from git-hashes). And just greping for "grafted from" gives me 425 results (in total -- if you want the log of individual branches, you need to use the `-b` option). For a more precise count, you should grep for hexadecimal numbers longer than a few digits inside the commit messages.
I somewhat doubt that any existing hg->git converters automatically translates these hashes, but I'd be very happy if someone finds out otherwise. Changing these manually is definitely not an option.
Also, if we stayed with mercurial, but used a different provider, we can't modify the history, because that would influence all the hashes (but then only the 9 direct links to "bitbucket.org/..." you found would be broken, which is acceptable, IMO)
Of course we can just ignore these links (though I think broken links/hashes are even worse than non-existing ones ...) 


Another point are links inside the codebase that point to bitbucket.

Following the same logic as above I use

hg grep "bitbucket.org"
and get 11 links (all seem to be the same). Again something fixable manually. 

Agreed, this part is easy to fix manually.
c) Fixing external links to the repository. Most notably, any links from our bugtracker will eventually fail (even if we stayed with bitbucket, the hashes won't match). I doubt that we could set up any automatic forwarding for that.
This might be by far the most complicated point since a lot (the majority?) of all issues contain links to commits. If desired I can find a concrete number but I doubt that it will be very...motivating. I also doubt that Bitbucket will provide any functionality to redirect links to other Git providers but I could image that there could be some workaround if we decide to migrate to Bitbucket Git. Something we should keep in mind before choosing a new provider.
If you (or anyone else) are/is really interested, I can try to make a MySQL dump of the underlying database (I'd need to strip the user data). If we have some automatic translation between the hashes, this could even allow us to automatically convert all links. Migrating to bitbucket-git will still break all existing links, since the hashes don't match. And as bitbucket is not even planning to provide an automated repository conversion, I would not count on any kind of forwarding mechanism.
Any third-party which relies on our main repository will need to change as well (not directly "our" problem, but we need to give a reasonable amount of time for everyone to migrate to whatever will be our future official repository).
It's currently unclear for me what exactly will happen with the hg repo but I guess it will be archived or something similar. In this case we can link to the new repo on the README page. I don't have any further ideas regarding this but also think we should migrate somewhat fast.
Yes, I think this is unclear for everyone at the moment. The announcement from bitbucket sounds a lot like they will literally delete all hg-repositories in June next year :( If it was at least frozen/archived as it is, we would have almost no problems with point c).
For manual redirection, we can of course open a new git-project which just contains a README.md saying that bitbucket dropped hg-support, and point to where Eigen migrated to. 


I see essentially three options:
1. Migrate to another mercurial provider
2. Convert to git, stay at bitbucket
3. Convert to git, migrate to another provider
1. We could migrate to Tuxfamily and keep mercurial. As you said this would imply we have to handle pull requests separately which is possible. As you surly know LLVM does exactly that by using Phabricator. However this would fix some of the issues above but links to bitbucket would remain a problem. Another downside of mercurial is that only very few projects are using it and contributing would be much easier in the case of git.
I really don't see much difference in usability between hg and git -- both have their advantages and little quirks, IMO. And I don't think that hg was ever the main-hurdle for people contributing to Eigen ...
If Phabricator allows to import our existing PRs that would of course be a nice option. But I'm really pessimistic about that at the moment, since this also requires to match all users which made the PR or took part in the discussion to the new host (maybe that would be the only argument for staying with bitbucket).
2. The only reason I see for this is the one I mentioned above: If there is (or will be) any support to redirect bitbucket links it will most likely only work if we stay at bitbucket. Compared with other code hosting services I find bitbucket (not mercurial) to be really complicated and not intuitive.
It might be an option, if they allowed to automatically migrate pull-requests. But at the moment, they don't even seem to plan automatic migration of repositories.
3. In an ideal world this would be my absolute preference (not very surprising). Regarding the choice of a service I want to make the personal point that I would rather migrate to Gitlab than to Github because it is as least as good as Github and I think that diversity of tools and providers is crucial for open source. In the long run we could even think about migrating issues to Gitlab and installing test runners (this is another story).
In my ideal world, somebody volunteers to do the work necessary for migration :) -- including the issues I pointed out (doesn't have to be the same person doing everything, of course). Even some proof-of-concept demos what can be automated would be nice!
I don't have any real preferences between mercurial/git or github/gitlab/bitbucket.
I totally agree that having automated test runners on pull-requests will be a big plus (for which I'm even willing to sacrifice some of my original points, especially since we may need to anyway). 

Cheers,
Christoph




Thanks,
David
On 21. Aug 2019, at 14:53, Christoph Hertzberg <chtz@xxxxxxxxxxxxxxxxxxxxxxxx> wrote: 

Hello Eigen users and contributers!
As some may have noticed, bitbucket/atlassian is "sunsetting" its mercurial support: 

https://bitbucket.org/blog/sunsetting-mercurial-support-in-bitbucket
If they stick to their timeline, we will have to migrate until June 1st, 2020. That means we still have time, but if we do nothing, things will break ...
Converting the repository itself to git should not be a bigger issue -- and if we do this we could as well migrate to a more mainstream provider (i.e., github). 

I think the main problems for migration are:
a) Migrating open pull-requests (for historical reasons, the closed/merged ones should probably be archived as well) b) Fixing internal links inside commit messages ("grafted from ...", "fixes error introduced in commit ...") c) Fixing external links to the repository. Most notably, any links from our bugtracker will eventually fail (even if we stayed with bitbucket, the hashes won't match). I doubt that we could set up any automatic forwarding for that. d) Any third-party which relies on our main repository will need to change as well (not directly "our" problem, but we need to give a reasonable amount of time for everyone to migrate to whatever will be our future official repository). 

Smaller issues (relatively easy to fix or not as important):
e) Change links from our wiki (to downloads)
f) Change URLs for automated doxygen generation and for unit-tests
g) Automatic links from the repository to our bugtracker (currently "Bug X" automatically links to http://eigen.tuxfamily.org/bz/show_bug.cgi?id=X) 
h) Change hashes in bench/perf_monitoring/changesets.txt

I probably missed a few things ...


I see essentially three options:
1. Migrate to another mercurial provider
2. Convert to git, stay at bitbucket
3. Convert to git, migrate to another provider
Honestly, I see no good reason for option 2. And the only real reason I see for option 1 would be that it safes a lot of hassle with b) and h) -- also perhaps it would simplify c) (e.g., we could easily crawl through our bugzilla-database and just replace some URLs).
Any opinions on this? Preferences for how to proceed, or other alternatives? Does anyone have experience with migrating from hg to git? Or migrating between providers? Especially, also dealing with the issues listed above. 
Does anyone see issues I forgot?


Cheers,
Christoph

Mail converted by MHonArc 2.6.19+ http://listengine.tuxfamily.org/