DVCS with a Windows central repository

Question

We are currently using VSS for version control. Quite few of our developers are interested in a distributed model (And want to get rid of VSS). Our network is full of Windows machines and while our IT department has experience maintaining Linux machines they would prefer not to.

What DVCS systems can host their central repository on Windows while providing..

1. Push access to the repository.
2. Basic authentication. Mostly just a way to allow or deny access to the whole repository. No need for fine grained access.
3. Server process so users don't need write right to the repository reducing the risk of accidentally messing with it.

On the client side a GUI such as Tortoise would be more or less a requirement (Sorry, Windows shell sucks. :|). Ease of installation would be a huge plus as our IT department is already quite low on resources. And using windows credentials for authentication would be an advantage but not a requirement as long as the client is able to store the credentials.

I have had a (really) quick look at Git, Mercurial and Bazaar.

• Git seemed to use ssh or simple WebDAV for repository access, requiring write permission for the users.
• Mercurial had a built in http server, but this seemed to be only for pull purposes. Update: Mercurial supports push as well.
• Bazaar Seemed to use sftp for repository access, again requiring a write permission for the users.

Are there windows server processes for any DVCS systems and has anyone managed to set one up in a Windows land?

And apologies if this is a duplicate question. I couldn't find one.

Update

Got Mercurial working for push purposes! Detailed list what was required can be found as an answer below.

Answer 1

Mercurial's almost certainly your easiest option on Windows.

If you didn't care about authentication, you actually can trivially allow hg serve to permit push. To do so, you merely need to add the following to the .hg/hgrc file in the repository you wish to serve:

[web]
allow_push = *
push_ssl = false

The first line says that anyone may push to this repository. The second tells Mercurial to allow pushing without SSL, since hg serve does not currently natively support HTTPS. At this point, users can push to your repository without having an account anywhere. If you're simply a small shop, that's probably fine--especially since you can use Mercurial's ability to sign changesets to guarantee a much higher level of verifiability than HTTP Basic will provide, anyway.

For a larger, shop, though, you'd be totally right in wanting at least a simple barrier for committing. To do that, you need to make two changes. First, you'll need to put Mercurial behind a web server with either reverse proxy support or CGI support. Thankfully, recent versions of IIS support both. You can consult the CGI directions in the Mercurial Redbook for Mercurial-specific steps, and Microsoft's guide to setting up CGI applications in IIS 6 for help on the IIS side.

Next, you'll need to set up some basic authentication. IIS provides HTTP Basic out-of-the-box, which, as a bonus, can authenticate directly against your domain, keeping administrative overhead to a minimum.

Finally, you'll want to change the allow_push line to support only specific users by specifying a comma-delimited list of user names. For example:

allow_push = benjamin, ted, the_cow

That's it. Mercurial will now allow push from users who can authenticate via HTTP Basic authentication, and allow pull from everyone else.

Answer 2

After Benjamin pointed out the HTTP serving CGI scripts I decided to try those out and managed to get a repository hosted over HTTP. The Redbook which Benjamin linked was of much help as were two Mercurial wiki articles. One which describes Mercurial publishing in general and another containing step by step instructions for setting up the HgWebDir CGI script.

These instructions weren't completely foolproof though so I had to poke around a bit. Most likely as I'm running 64bit Vista. The instructions below document what I did. Now that I've done it once I'd probably do things in another order so don't consider these step by step instructions.

Mercurial

First I acquired the Mercurial binary from http://mercurial.berkwood.com/ which got installed into d:\dev\Mercurial. I created a repository for testing under d:\dev\testRepo repository using hg init. The d:\dev\Mercurial\library.zip contains Mercurial library files required by the CGI script so they were extracted to d:\dev\Mercurial\library. Something which confused me at first is that when I opened the zip file I received an error message and saw no contents. Just extracting the file to a directory worked though.

For the web script, I downloaded Mercurial source which contained the hgwebdir.cgi which got moved and renamed to d:\dev\Mercurial\webroot\hgwebdir.py. The step by step article contains good instructions for modifying the hgwebdir script for Windows. They also contain instructions for hgweb.config which in my case ended up looking like this:

[paths]
/hg/hgwebdir.py/test = D:\dev\Mercurial\testRepo

Also the repository wanted the following config so I could push there without SSL. Note I am using Basic Authentication to authenticate users currently. I had to create the config in D:\dev\Mercurial\testRepo\.hg\hgrc and add the following lines to it:

[web]
allow_push = *
push_ssl = false

Python

The CGI script is a Python script so it requires Python. It's seems pretty picky on which Python version executes it. One of the articles mentioned that running it requires same version that was used to build the Mercurial. In the end I got it working on Python 2.5 x86 after trying Python 2.6 x64, Python 2.4, Python 2.5 x64.

IIS

Two things I missed and had to install were CGI support and Basic Authentication. Both of these were installed through Control Panel, Programs and Features. Once done with installation I created a virtual directory (Which I later changed to an Application) in IIS pointing to D:\dev\Mercurial\webroot. The virtual directory required an CGI handler for *.py files which could be added from Handler Mappings. The executable was D:\dev\SDKs\Python25_x86\Python.exe %s. Once IIS had permissions to the webroot directory I could navigate to http://localhost/hg/hgwebdir.py/test and see the repository.

So now the read access was working. When I tried pushing to the repository I received weird error messages telling me it wasn't a real repository.

After an hour of debugging I ended up copying the whole D:\dev\Mercurial\library\mercurial tree under webroot so that Python could find D:\dev\Mercurial\webroot\mercurial\hgweb\hgwebdir_mod.pyc. After this Wireshark was reportting Access Denied errors in the stack trace. No idea what the real reason to this was but changing the virtual directory into an Application in IIS and moving it on top of an application pool which ran using Local System account the access denied errors went away.

Also at some point I gave HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WinSock2\Parameters registry key more permissions so IIS could access it. Doubt that it requires these after using Local System account.

Once these were done pushing stuff to the repository using hg push http://localhost/hg/hgwebdir.cgi/test was working!

Problems and solutions

• Where to find the library files.
  • They were in the library.dll under Mercurial installation folder. I just had to extract them even if my unzip program refused to view me its contents.
• How to get the Python script to run
  • Download the correct Python version for x86 architecture as the script uses some x86 libraries. The correct Python version depends on the Mercurial version. For 1.2.1 it was Python 2.5 x86.
  • Alternatively you could try building Mercurial from sources with whatever Python version you want but in my case this failed when building extensions.
• How to set CGI up in IIS
  • First make sure CGI is installed in IIS. This wasn't assumed to be true in the IIS instructions Benjamin posted.
  • Create a new Module Mapping for *.py in IIS Handler Mappings. The correct Module is CgiModule and the executable is your Python executable + %s
• How to allow the CGI script to write to the repository
  • Make sure the script has everything it requires. I had to move the library\mercurial\hgweb\hgwebdir_mod.pyc to another place.
  • Make sure the script has permissions to everywhere it wants. I solved this by Creating a new Application Pool for the CGI script that used Local System account, converting the Virtual Directory to an Application in IIS and selecting the new Application Pool.

Answer 3

After reading Mikko's Answer which almost worked for me, I came up with my own notes for installation. My setup was designed to be a "non protected and open" repository that members of my team could use installed on a Windows 2008 Server.

1. Install Python.

The version of Python I used was Python 2.6.2 and I used the Windows x86 MSI Installer.

• Install for all Users.
• Install to C:\Mercurial\Python
• Use Default Feature Options.

2. Install MinGW.
The version of Minimalist GNU for Windows I used was MinGW 5.1.4

• Install the MinGW-5.1.4.exe.
• Choose the Download and Install Option.
• Choose the Current Package Option to Install.
• For the Components to Install Select the "Minimal" option.
• Install to C:\Mercurial\MinGW

3. Modify your path.

You need to add in locations to your environmental path at this point.

• Add 'C:\Mercurial\Python26;C:\Mercurial\MinGW\bin' to the path (Order Matters.)

4. Install Mercurial.

The version of mercurial that I used was the latest release in the stable branch and I did not use the binaries, but used the source code. I wanted to compile mercurial myself so that it would work with whatever version of Python I had installed so I didn't have to worry about any compatability issues which I found to be the biggest challenge with other install methods. The easist way to get the source is by downloading the "zip" file. Mercurial Stable Release

• Extract Zip File to C:\Mercurial\Source.
• Build the Source at command prompt.

python setup.py build --force -c mingw32
python setup.py install --force --skip-build

5. Modify your path.

You need to insert into your environmental path another location for the 'hg' command.

• Add 'C:\Mercurial\Python26\Scripts;C:\Mercurial\Python26;C:\Mercurial\MinGW\bin' to the path (Order Matters.)

6. Create your Config file.

You need to have a default user name set if your going to do any commits locally on this server.

• Create file '"C:\Documents and Settings{username}.hgrc"'

[ui]  
editor = Notepad  
username = your_name 

6. Test your Install.

Open up a new command window and test with 'hg debuginstall' to validate. You should see something like the following.

Checking encoding (cp1252)...  
Checking extensions...  
Checking templates...  
Checking patch...  
Checking commit editor...  
Checking username...  
No problems detected  

7. Setup Web Directory.

• Create Directory 'C:\Mercurial\Web'
• Copy the hgwebdir.cgi file from the 'C:\Mercurial\Source' to 'C:\Mercurial\Web'

8. Configure IIS7 for Centralized Repository.

I used the DefaultAppPool which is using .Net 2.0, Pipeline=Integrated, Identity = ApplicationPoolIdentity.

• Ensure CGI features are available in IIS7.
• Control Panel/Programs/Windows Features/IIS/App Development Features/CGI
• Add App into IIS on the Website you wish.
• Alias=Mercurial -- Physical Path=C:\Mercurial\Web
• On the App select HTTP Modules and add a new Module Mapping.
  • Request Path=*.cgi, Module=CgiModule, Executable=C:\Mercurial\Python26\python.exe %s, Name=Mercurial.
  • When Prompted to add entry to ISAPI and CGI restrictions list say yes.

9. Test your Web Setup.

You should now be able to browse http://localhost/Mercurial/hgwebdir.cgi and see and empty repository list.

10. Configure IIS7 for Friendly URL

I did not like having the unfriendly URL and this step allows us to remap the URL to something more friendly. Install the URL Rewrite Moduel 1.1 Extension for IIS.

• On the Mercurial IIS Application in IIS Manager featurs View select URL Rewrite Component and install a new Rule.
• Choose Add Rules, then the Template 'Rule with rewrite map.' Rule Action=Rewrite, Specify Rewrite Map=Mercurial
• Add a mapping Entry. OriginalValue='/Mercurial/Repo', New Value='/Mercurial/hgwebdir.cgi'

11. Create Mercurial Repository

You can now create a test repository.

• Create a Directory C:\Mercurial\Repository and ensure IUSR account has the permissions to write to the directory. (If on Domain account is more like IUSR_{ComputerName}.
• Create file C:\Mercurial\Web\hgweb.config to list the repositories.

[paths]
/ = C:\Mercurial\Repository\**

• Add a directory C:\Mercurial\Repository\Test and initialize the repository with 'hg init'

** If you want now to be able to push without ssl create in the .hg directory of the repository a hgrc file the following lines.

[web]
allow_push = *
push_ssl = false

References:

Mercurial Wiki Windows Install
HG Book
Step by Step
Publishing Mercurial Repositories

Answer 4

For a team taking the first step away from VSS I would have suggested using SubVersion for source control and either TortoiseSVN or VisualSVN for the client.

But if the team has made the decision to switch to a DVCS then I'd suggest Mercurial because of it's better support for HTTP and windows on the client via TortoiseHg.