Configuring HgWeb in IIS on Windows

This page describes how to get HgWeb running on

1. Creating the HgWeb Website

Install Python 2.6. By default, this installs to C:\Python26. On this page, the Python installation folder is referred to as PYTHON_HOME.

Create an HgWeb website in IIS. We'll call the path to this website's root directory HGWEB_ROOT.

Create a web.config file in HGWEB_ROOT. Edit it to look like this:

<?xml version="1.0" encoding="UTF-8"?>
      <add name="Python" path="*.cgi" verb="*" modules="CgiModule" scriptProcessor="PYTHON_HOME\python.exe -u &quot;%s&quot;" resourceType="Unspecified" requireAccess="Script" />

You'll then need to enable the Python module. From a command prompt, run:

> C:\Windows\system32\inetsrv\appcmd set config /section:isapiCgiRestriction /+"[path='C:\Python26\python.exe -u %22%s%22',description='Python',allowed='True']"

You should have everything configured to start running CGI scripts through Python. To test that it's working, create a test.cgi file in HGWEB_ROOT:

   1 print 'Status: 200 OK'
   2 print 'Content-Type: text/html'
   3 print
   4 print '<html><body><h1>It Works!</h1></body></html>'

Save the file. Hit the test.cgi file in your web browser. If you see It Works!, you've got the Python CGI handler installed correctly.

2. Adding Mercurial to Python

Create an empty file named hgweb.config in your HgWeb root directory. This is where the HgWeb configuration goes once everything is working.

Download and run the Mercurial Python module installer (it's the one whose description says "use this for running hgweb"). After installation, you should see mercurial and hgext directories in your PYTHON_HOME\Lib\site-packages directory. If you don't see those directories, you chose the wrong installer.

Download the hgweb.cgi script for your version of Mercurial. Browse the Mercurial source code. Click the the tag for your version, click Browse in the navigation menu, click the hgweb.cgi script, then right-click Raw from the navigation menu, choose Save As... and save the file into your HgWeb directory.

Open hgweb.cgi and change the value of the config variable to point to the hgweb.config file you created earlier:

   1 config = "HGWEB_ROOT\hgweb.config"

Hit the hgweb.cgi script in your web browse and you should see the HgWeb interface.

3. Configuring URL Rewrite Rules

Now, we need to create some URL rewrite rules so that URLs to your repositories don't have hgweb.cgi in them.

First, you'll need to download and install version 2 of the Url Rewrite Module.

Once that is finished, edit the HGWEB_ROOT\web.config file and add the following <rewrite> section under <system.webServer>:

        <rule name="rewrite to hgwebdir" patternSyntax="Wildcard">
          <match url="*" />
          <conditions logicalGrouping="MatchAll" trackAllCaptures="false">
            <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
          <action type="Rewrite" url="hgweb.cgi/{R:1}" />

You should now be able to hit your website without hgweb.cgi in the URL and see the HgWeb UI.

4. Authenticating Against Active Directory

Add the following to your HgWeb's web.config, in the /configuration/system.webServer/security/authentication section:

<?xml version="1.0" encoding="UTF-8"?>
        <basicAuthentication enabled="true" realm="YOUR_DOMAIN" defaultLogonDomain="YOUR_DOMAIN" />
        <anonymousAuthentication enabled="true" />

Replace YOUR_DOMAIN with the name of your Windows domain. Anonymous authentication is enabled so you can support unrestricted repositories (e.g. allow_push=*).

You'll need to unlock the basic authentication configuration section so it can be configured in your web.config:

> C:\Windows\system32\inetsrv\appcmd unlock config /section:basicAuthentication

You can test that authentication is working by adding an allow_push setting to the repository's .hg\hgrc file on the server:

allow_push = USERNAME

Commit a change an attempt a push. You should see a sequence like this:

> hg push
pushing to https://localhost:4301/cm
searching for changes
http authorization required

Warning Remember that basic authentication sends usernames and passwords over the network in the clear. Anyone on the network will be able to read the user's credentials. We strongly recommend securing connections with SSL. Generating an SSL certificate and assigning it to your HgWeb website is beyond the scope of this article.

5. File System Permissions

IIS starts CGI processes as the user being authenticated. For un-authenticated, anonymous users/requests, the CGI process is started as the website's application pool identity. For authenticated users/requests, the CGI process is started as the authenticated user. Make sure you set proper NTFS permissions on your server-side repositories. Anybody who needs read-only access should have Read & execute, List folder contents, and Read permissions. Anybody who needs read/write access should have Modify, Read & execute, List folder contents, Read, and Write NTFS permissions. We recommend creating groups for each set of users for each repository, and grant the appropriate NTFS permissions to those groups. To grant someone permission, add them to the appropriate group.

6. Running via ISAPI

While running hgweb.cgi is fairly easy, CGI is rather slow way of serving pages. If more speed is required you should consider using ISAPI. Basic steps are described in contrib/win32/ in Mercurial repository and in blog post ( wayback archive).

Please note that some combinations of Windows/IIS/Python/Mercurial will not work. For example Windows Server 2008 R2 64 bit with Python 2.6 32 bit and precompiled 32 bit Mercurial are not working and result in Error 500 and such message:

Failed to import callback module 'hgwebdir_wsgi'
The specified module could not be found.

This is probably because of mix of involved CRTs.

7. Troubleshooting

7.1. I'm getting an HTTP 400: Bad request error. What's going on?

This happens when Mercurial sends more request headers than IIS can handle. IIS may return an error page that says HTTP Error 400. The size of the request headers is too long.

By default, IIS limits the entire request header (i.e. the total size of all the headers in the request) to 16,384 bytes. If you have a repository with a lot of heads/branches, you can easily exceed this limit.

This setting is controlled by the MaxRequestBytes HTTP.sys registry setting. The default value is 16,384 bytes. The maximum value is 16,777,216 bytes (approximately 16MB).

To change this setting, in the HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\HTTP\Parameters registry key, add a MaxRequestBytes DWORD whose value is the number of bytes you'd like to allow for a request's headers. You'll then need to restart the HTTP service and the World Wide Web Publishing Service.

net stop w3svc
net stop http
net start http
net start w3svc

Alternatively a server-side hgrc setting [experimental] httppostargs = true can fix the problem in Mercurial. Mozilla uses this.)

8. See also

CategoryWeb CategoryHowTo CategoryTipsAndTricks

HgWebInIisOnWindows (last edited 2018-04-16 13:04:02 by PeterSuter)