Reverse Proxy Server 2: SVN

Uniform Server 5.0-Nano Reverse Proxy.

How to run a subversion server behind a reverse proxy.

On the previous page I mentioned an SVN server requires special consideration. Basic requirement is for a proxy server to push everything over to the back-end server and let it do its job such as verification and copy and move.

Subversion uses the DAV (Distributed Authoring and Versioning) Protocol it uses more methods than standard HTTP (eg. GET, COPY, MOVE) these must be passed to the back-end server hence special consideration. In addition more headers are used compared to standard HTTP. Again these must be taken into account.

Preparation

For this example we require a subversion server.

Create a new folder C:\server_c Extract a copy of UniServer 5.0 to this folder.

1)	Move Servers First close all running servers. Run Unitray: C:\server_c\UniServer\Start.exe Left click tray icon > Advance > Move Servers multi-server operation Press enter at all prompts Repeat 2 and 3 Until icon 4 is displayed	Moves servers and also configures server's internal paths. Apache port = 83
2)	Inside folder C:\server_c\UniServer create two new folders svn_tools and svn C:\server_c\UniServer\svn_tools C:\server_c\UniServer\svn	You can choose different names and locate these outside of the UniServer folder. However we are placing these here for portability. Folder svn will contain our SVN repositories]].
3)	Download File: svn-win32-1.6.4.zip or newer. Located at the bottom of this page: tigris.org Extract to any folder	Make sure any newer version is compatible with the version of Apache.
4)	Copy the entire content of folder svn-win32-1.6.4\svn-win32-1.6.4 To folder C:\server_c\UniServer\svn_tools Folder svn_tools will now contain folders bin, iconv, licenses, share and file README.txt	Once copied if you wish to save space delete the extracted files and svn-win32-1.6.4.zip they are no longer required.
5)	Navigate to C:\server_c\UniServer\svn_tools\bin Move files: mod_authz_svn.so and mod_dav_svn.so To folder: C:\server_c\UniServer\usr\local\apache2\modules	Move the two modules to Apache's module folder;
6)	Navigate to C:\server_c\UniServer\svn_tools\bin Copy these files: intl3_svn.dll libdb44.dll libsvn_delta-1.dll libsvn_fs-1.dll libsvn_repos-1.dll libsvn_subr-1.dll To: C:\server_c\UniServer\usr\local\apache2\bin	The above two modules have dependencies (dlls), Apache resolves dependences by first looking in its bin folder and then looks along system paths. Generally these dlls are located on a system path however we want a portable installation hence they are copied to Apache’s bin (binary) folder.
7)	Edit file: C:\server_c\UniServer\usr\local\apache2\conf\httpd.conf Confirm these modules are enabled as shown: LoadModule dav_module modules/mod_dav.so LoadModule dav_fs_module modules/mod_dav_fs.so	Configure Apache to use the subversion module. First check these modules are enabled. Note, mod_dav.so is enabled by default.
8)	At the end of load modules section add these two lines: LoadModule dav_svn_module modules/mod_dav_svn.so LoadModule authz_svn_module modules/mod_authz_svn.so	The two lines inform Apache to load the svn modules. Add them just below: LoadModule vhost_alias_module modules/mod_vhost_alias.so
9)	At the end of httpd.conf, add the following block of code. <location /svn> DAV svn SVNListParentPath on SVNParentPath C:/server_c/UniServer/svn </location>	svn Top level folder name http://localhost/svn/*** any name after svn is assumed a repository request and passed to DAV for resolving DAV svn Instructs Apache to pass the request onto the DAV layer for processing as a subversion (svn) request. SVNListParentPath on Enables listing of all repositories for URL http://localhost/svn SVNParentPath Absolute path to the parent folder containing all the repositories.

Testing SVN server

• Restart Servers
• Access the SVN repository. Type the following into a browser http://localhost:83/svn

Page displays

Collection of Repositories
Powered by Subversion version 1.6.4 (r38063).

This confirms Apache has been configured correctly. Next step is to create an SVN repository.

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Creating a repository

This section shows how to create a repository using the command line tool svnadmin.exe and how to add a working project.

Batch file

To run the admin tools requires opening a command prompt and navigating to the svn_tools executables folder .

This is very tedious hence create the following batch file in folder C:\server_c\UniServer\svn_tools\bin

Name the batch file whatever you like I have named it z_start_svn_command_prompt.bat add the following content:

start "SVN COMMAND PROMPT" cmd.exe /k "COLOR B0" 

Double click to run, a new command prompt is opened and the working folder is automatically set.

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Create a repository

You need to create at least one blank repository choose a name that matches your project for this example I will use “myproject”

Run the batch file above and type the following command:

svnadmin.exe create ..\..\svn\myproject

• svnadmin.exe Runs the subversion administration program.
• create Is the command to be run by svn admin. It creates a repository named myproject.
  • Note: You can specify an absolute path or a relative path to the folder myproject.
    For example:
    Absolute: C:\server_c\UniServer\svn\myproject
    Relative: ..\..\svn\myproject - as shown above
• If the folder myproject does not exist it is created. Adds subversion database and tracking folders.

Repository Access

Start the servers. To access repositories type either of the following into a browser:

1. http://localhost:83/svn/ -- Displays Collection of Repositories page.
   1. All repositories in folder svn are listed as links.
   2. Currently we have just one repository hence a single link “myproject” is displayed
   3. Click this link to display “myproject” repository.
   4. If you do not want all repositories listed comment this line as shown: #SVNListParentPath on
      Accessing http://localhost:83/svn/ will now produce Forbidden You don't have permission to access /svn/ on this server.
   5. You can still access a repository by entering its full URL see below.
       
2. http://localhost:83/svn/myproject/ -- You directly access a repository by name as shown for "“myproject”.
   Viewing this repository with a browser you will find it empty.
   However view the same folder using Windows Explorer displays several SVN suport folders and files.
   1. Folders: conf, dav, db, hooks and locks
   2. Files: README.txt and format
   3. Never edit or delete the above folders or files. They tag and track all changes in a repository.

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Command line client

Starting with an empty repository you probably want to quickly set it up and publish your current project as it stands.

The following shows a quick way to do this it also includes SVN’s recommended folder structure.

1. Create a temporary folder for example C:\a_svn_temp
2. Inside this create three new folders (SVN recommended) names:
   1. trunk
   2. tags
   3. branches
3. Copy your current stable project into folder trunk -- Note: For testing I copied folder C:\server_c\UniServer\unicon
4. Start servers
5. Run batch file z_start_svn_command_prompt.bat (whatever you named it)
6. Type the following:

svn.exe import C:\a_svn_temp http://localhost:83/svn/myproject -m "Initial import"

This updates your repository with new folder structure and project.

View repository, type into browser http://localhost:83/svn/myproject

• The project page and status are displayed myproject - Revision 1:

Note: If you do not include -m "Some text" SVN will complain about not being able to find a text editor.

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Summary

The above server is intentionally non-restrictive meaning anyone can access and change repositories. We will add security latter a non-restrictive server allows configuration in simple stages making it easier to test.

Currently we have a functional SVN server, its fully portable and can be relocated on a new host machine. The real objective was to proxy it, this is covered on the next page.

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Ric