Is it possible to prevent someone from pushing commit which touches already applied (committed to separate branch) database migrations?
For example, in default branch there are existing migrations 01 and 02 (already applied). In development branch someone adds migration 03 but also modifies migration 02. How to prevent this commit via mercurial hook?
You can write a pretxnchangegroup hook that checks for commits that modify an existing file in the migrations directory. Shouldn't be that hard to cobble something together with some hg API docs.
Related
We have a project that lives in a mercurial repository.
Our customer would like to take ownership of the code base by doing the following:
Set up a mercurial repository on a server belonging to the customer.
Import the existing code into the new mercurial repository.
What is the best way to achieve step 2?
Is it a simple matter of doing the following:
Clone the existing mercurial repository:
hg clone <existing mercurial repo URL>
Push the cloned repository into the new one:
hg push <new mercurial repo URL>
Am I missing any steps? What about the hgrc file? Does it have to be modified in any way prior to pushing the project into a new repository?
Yes, you can do what you state, however it is worth noting that if you do a simple hg clone of your main repository, then a link will exist between the two, which may not be what you want. You can remove this link by editing the .hg/hgrc file and removing the default = ... item in the [paths] section.
I find that a better way is to do it without cloning. This way you don't have the link between repositories, which as this is going to a customer may be what you want.
The basic method is to set up a new repository with no changesets, and then bring in all of the changesets in one of three ways:
Push the changes from your repository to the new repository.
Pull the changes from into the new repository from the old.
If you don't have access to the new repository, create a bundle that can be provided to the customer - this can then be unbundled or pulled into the empty repo.
Pushing and Pulling is done as you normally would, but specifying the repository location:
// create the empty repository
hg init .
// pull in everything from the old repo
hg pull /projects/myOriginalRepo
or to push...
// create the empty repository
hg init /projects/myNewRepo
cd /projects/myOriginalRepo
hg push /projects/myNewRepo
Creating a bundle is perhaps a nicer way, as you can write the bundle onto a DVD and give it to your customer wrapped in a bow with a nice greeting card:
cd /projects/myOriginalRepo
hg bundle --all ../repo.bundle
Everything gets written out to a single file, which can then be extracted with hg unbundle repo.bundle or hg pull repo.bundle, into a repository with no existing changesets.
Regarding the hgrc file, as already mentioned in another answer it is not a controlled file, and so won't be copied. However, any contents are likely things like hooks to perform auto-building, or validating changesets before they are applied. This is logic which would probably only make sense to your own organisation, and I would suggest you wouldn't want this to be imposed on your customer - they are, after all, taking ownership of your code-base, and may have their own systems in place for things like this.
In the simple case - it's all.
But if you have modified .hg/hgrc file then you need to move it to the remote server manually and (if necessary) modify it correspondingly to a new environment.
Ie: you could have hooks set up in the original repository.
As of clients - just change a path to a repository in a default section (or any other section if you have several specified)
To move the master repository, you need to (a) create the new master repo and (b) tell the existing clients about it.
Create the new master repo any way you want: cloning or init+pushing, it makes little difference. Be sure to move any contents of the old repo that are not under version control, including .hgrc and any unversioned or ignored files that are not discardable. If you cloned, edit the new master's .hgrc and remove the default path, so that it doesn't try to talk to the old master repo any more.
Existing clones of the old master repo still push/pull from the old master. Everyone must edit their .hgrc, updating default (and/or default-push) so that it points to the new location. (They may also need to update authentication credentials, of course).
Only then is the migration complete. Remove (or move/hide) the original repo so that if someone forgot to update their repo path, they'll get an error on push/pull instead of pouring data down a memory hole.
I have in some cases a need to enforce that Mercurial-users have run hg pull -u before any hg commit can be allowed, i.e., hg pull will mean that the incoming queue is empty — and furthermore I also want that the person is using the head version of the branch.
How can I set up such a restriction?
(I am fully aware that this goes against parts of the DVCS design core)
You could ask your developers to install
[hooks]
pre-commit = hg pull -u
in their config files (it should probably be installed in the per-repository .hg/hgrc file since this workflow is repository specific).
This makes Mercurial a little Subversion-like: your developers will only have one outstanding changeset. But note as soon as someone pushes to the server, hg pull -u cannot update to the new branch tip since it will cross branches (topological branches) to do so. So a proper merge will be needed at that point (or a rebase, see hg pull --rebase).
Normally mercurial will NOT let you push an open head to the server without using the -f flag (force). You can write a hook to pull automatically but that can not be enforced server side due to the server not knowing what you have. There is an article on mercurial's website about this scenario:
https://www.mercurial-scm.org/wiki/TipsAndTricks?highlight=%28heads%29#Prevent_a_push_that_would_create_multiple_heads
As Adam says, perhaps what you really need to do is prevent multiple heads (per branch). This is what we do, using the 'forbid_2head' hook from Netbeans (linked from here https://www.mercurial-scm.org/wiki/TipsAndTricks#Prevent_a_push_that_would_create_multiple_heads)
The result is that the hook prevents any push that creates multiple heads on a branch (so one on the anonymous/default branch plus one each on named branches). This effectively forces a pull before commit because you have to pull, get the two heads locally, then merge or rebase to remove it.
note, the hook is on the server/master repo
I am developing a web database that is already in use for about a dozen separate installations, most of which I also manage. Each installation has a fair bit of local configuration and customization. Having just switched to mercurial from svn, I would like to take advantage of its distributed nature to keep track of local modifications. I have set up each installed server as its own repo (and configured apache not to serve the .hg directories).
My difficulty is that the development tree also contains local configuration, and I want to avoid placing every bit of it in an unversioned config file. So, how do I set things up to avoid propagating local configuration to the master repo and to the installed copies?
Example: I have a long config.ini file that should be versioned and distributed. The "clean" version contains placeholders for the database connection parameters, and I don't want the development server's passwords to end up in the repositories for the installed copies. But now and then I'll make changes (e.g., new defaults) that I do need to propagate. There are several files in a similar situation.
The best I could work out so far involves installing mq and turning the local modifications into a patch (two patches, actually, with logically separate changesets). Every time I want to commit a regular changeset to the local repo, I need to pop all patches, commit the modifications, and re-apply the patches. When I'm ready to push to the master repo, I must again pop the patches, push, and re-apply them. This is all convoluted and error-prone.
The only other alternative I can see is to forget about push and only propagate changesets as patches, which seems like an even worse solution. Can someone suggest a better set-up? I can't imagine that this is such an unusual configuration, but I haven't found anything about it.
Edit: After following up on the suggestions here, I'm coming to the conclusion that named branches plus rebase provide a simple and workable solution. I've added a description in the form of my own answer. Please take a look.
From your comments, it looks like you are already familiar with the best practice for dealing with this: version a configuration template, and keep the actual configuration unversioned.
But since you aren't happy with that solution, here is another one you can try:
Mercurial 2.1 introduced the concept of Phases. The phase is changeset metadata marking it as "secret", "draft" or "public". Normally this metadata is used and manipulated automatically by mercurial and its extensions without the user needing to be aware of it.
However, if you made a changeset 1234 which you never want to push to other repositories, you can enforce this by manually marking it as secret like this:
hg phase --force --secret -r 1234
If you then try to push to another repository, it will be ignored with this warning:
pushing to http://example.com/some/other/repository
searching for changes
no changes found (ignored 1 secret changesets)
This solution allows you to
version the local configuration changes
prevent those changes from being pushed accidentally
merge your local changes with other changes which you pull in
The big downside is of course that you cannot push changes which you made on top of this secret changeset (because that would push the secret changeset along). You'll have to rebase any such changes before you can push them.
If the problem with a versioned template and an unversioned local copy is that changes to the template don't make it into the local copies, how about modifying your app to use an unversioned localconfig.ini and fallback to a versioned config.ini for missing parameters. This way new default parameters can be added to config.ini and be propagated into your app.
Having followed up on the suggestions here, I came to the conclusion that named branches plus rebase provide a simple and reliable solution. I've been using the following method for some time now and it works very well. Basically, the history around the local changes is separated into named branches which can be easily rearranged with rebase.
I use a branch local for configuration information. When all my repos support Phases, I'll mark the local branch secret; but the method works without it. local depends on default, but default does not depend on local so it can be pushed independently (with hg push -r default). Here's how it works:
Suppose the main line of development is in the default branch. (You could have more branches; this is for concreteness). There is a master (stable) repo that does not contain passwords etc.:
---o--o--o (default)
In each deployed (non-development) clone, I create a branch local and commit all local state to it.
...o--o--o (default)
\
L--L (local)
Updates from upstream will always be in default. Whenever I pull updates, I merge them into local (n is a sequence of new updates):
...o--o--o--n--n (default)
\ \
L--L--N (local)
The local branch tracks the evolution of default, and I can still return to old configurations if something goes wrong.
On the development server, I start with the same set-up: a local branch with config settings as above. This will never be pushed. But at the tip of local I create a third branch, dev. This is where new development happens.
...o--o (default)
\
L--L (local)
\
d--d--d (dev)
When I am ready to publish some features to the main repository, I first rebase the entire dev branch onto the tip of default:
hg rebase --source "min(branch('dev'))" --dest default --detach
The previous tree becomes:
...o--o--d--d--d (default)
\
L--L (local)
The rebased changesets now belong to branch default. (With feature branches, add --keepbranches to the rebase command to retain the branch name). The new features no longer have any ancestors in local, and I can publish them with push -r default without dragging along the local revisions. (Never merge from local into default; only the other way around). If you forget to say -r default when pushing, no problem: Your push gets rejected since it would add a new head.
On the development server, I merge the rebased revs into local as if I'd just pulled them:
...o--o--d--d--d (default)
\ \
L--L-----N (local)
I can now create a new dev branch on top of local, and continue development.
This has the benefits that I can develop on a version-controlled, configured setup; that I don't need to mess with patches; that previous configuration stages remain in the history (if my webserver stops working after an update, I can update back to a configured version); and that I only rebase once, when I'm ready to publish changes. The rebasing and subsequent merge might lead to conflicts if a revision conflicts with local configuration changes; but if that's going to happen, it's better if they occur when merge facilities can help resolve them.
1 Mercurial have (follow-up to comments) selective (string-based) commit - see Record Extension
2 Local changes inside versioned public files can be easy received with MQ Extension (I do it for site-configs all time). Your headache with MQ
Every time I want to commit a regular changeset to the local repo, I
need to pop all patches, commit the modifications, and re-apply the
patches. When I'm ready to push to the master repo, I must again pop
the patches, push, and re-apply them.
is a result of not polished workflow and (some) misinterpretation. If you want commit without MQ-patches - don't do it by hand. Add alias for commit, which qop -all + commit and use this new command only. And when you push, you may don't worry about MQ-state - you push changesets from repo, not WC state. Local repo can also be protected without alias by pre-commit hook checking content.
3 You can try LocalBranches extension, where your local changes stored inside local branches (and merge branches on changes) - I found this way more troublesome, compared to MQ
After a change in my local repo, I commit with hg commit -m <message>, then I push to my server with hg push, then in my server I update working dir with hg update.
Is there a better way to do this?
The first two steps you have described:
hg commit -m <message>
hg push
are required as per the fact that commits are kept completely separate from the server in Mercurial (and most other DVCS as well). You could write a post-commit hook to perform the push after each commit, but this is not advised because it prevents you from correcting simple mistakes during the commit and before the push.
Because you're trying to perform an update on 'the server' I'm assuming you are executing a version of the code in your repository on the server. I'm assuming this because typically the server would simply act as a master repository for you and your developers to access (and also to be subject to backups, etc..), and would not need the explicit hg update.
Assuming you are executing code on the server, you can try and replace the push and the update with this command:
hg pull <path to development repo> -u
which will perform a pull from your local repo and then an automatic update. Depending on your server configuration, it might be difficult to get the path to your local repo.
For the first part of the question (ie. automatically push when you do a commit), you can use the trick described in this answer : mercurial automatic push on every commit .
If you want to automatically update the working directory, you can do this with a hook. Add this in the hgrc of your repository (.hg/hgrc on your server directory) :
[hooks]
changegroup = hg update >&2
This will automatically update the working directory every time a push is made to this server. This hook is described in the Mercurial FAQ.
If you use these 2 solutions, the next time you do hg commit -m "message", the commit will be automatically pushed to the remote server and the working directory on the server will be updated.
There is an extension called autosync you might find useful:
This extension provides the autosync command which automatically and continuously commits working copy changes, fetches (pull, merge, commit) changes from another repository and pushes local changes back to the other repository. Think of configuration files or to-do lists as examples for things to synchronize. On a higher level the autosync command not only synchronizes repositories but working copies. A central repository (usually without a working copy) must be used as synchronization hub:
It's my first time using a DVCS and also as a lone developer, the first time that I've actually used branches, so maybe I'm missing something here.
I have a remote repository from which I pulled the files and started working. Changes were pushed to the remote repository and of course this simple scenario works fine.
Now that my web application has some stable features, I'd like to start deploying it and so I cloned the remote repository to a new branches/stable directory outside of my working directory for the default branch and used:
hg branch stable
to create a new named branch. I created a bunch of deployment scripts that are needed only by the stable branch and I committed them as needed. Again this worked fine.
Now when I went back to my initial working directory to work on some new features, I found out that Mercurial insists on only ONE head being in the remote repository. In other words, I'd have to merge the two branches (default and stable), adding in the unneeded deployment scripts to my default branch in order to push to the main repository. This could get worse, if I had to make a change to a file in my stable branch in order to deploy.
How do I keep my named branches separate in Mercurial? Do I have to create two separate remote repositories to do so? In which case the named branches lose their value. Am I missing something here?
Use hg push -f to force the creation of a new remote head.
The reason push won't do it by default is that it's trying to remind you to pull and merge in case you forgot. What you don't want to happen is:
You and I check out revision 100 of named branch "X".
You commit locally and push.
I commit locally and push.
Now branch X looks like this in the remote repo:
--(100)--(101)
\
\---------(102)
Which head should a new developer grab if they're checking out the branch? Who knows.
After re reading the section on named branchy development in the Mercurial book, I've concluded that for me personally, the best practice is to have separate shared repositories, one for each branch. I was on the free account at bitbucket.org, so I was trying to force myself to use only one shared repository, which created the problem.
I've bit the bullet and got myself a paid account so that I can keep a separate shared repository for my stable releases.
You wrote:
I found out that Mercurial insists on only ONE head being in the remote repository.
Why do you think this is the case?
From the help for hg push:
By default, push will refuse to run if it detects the result would
increase the number of remote heads. This generally indicates the
the client has forgotten to pull and merge before pushing.
If you know that you are intentionally creating a new head in the remote repository, and this is desirable, use the -f flag.
I've come from git expecting the same thing. Just pushing the top looks like it might be one approach.
hg push -r tip