John Luif

My two previous posts talked about using MSBuild tasks to move ClickOnce deployments and Reporting Services reports.  In this post I wanted to show how to use MSBuild, PSExec and Linkd to set up deployments from a QA environment to a staging and finally a production environment.

PSExec allows users to execute process remotely on another box.  Using PSExec you can execute Linkd on another box to create or remove junctions.  A junctions is basically a pointer from one folder to another kind of  like a symlink (unix).  The one difference to note between junctions and symlinks is if you delete the folder that has a junction to another folder the other folder also gets deleted.  In IIS you can set up a website or virtual directory to point to any folder.  The folder that IIS is looking at can have a junction on it pointing to another folder.

Add in MSBuild and you get a targets like this:

<Target Name="RemoveStagedJunctions">
  <Exec
   Timeout="15000"
   ContinueOnError="true"
   Command='$(MSBuildProjectDirectory)\bin\psexec.exe \\$(WebServer) -n 15 "c:\program files\junction\linkd.exe" $(StagedLocation) /D'>
  </Exec>
 </Target>

 <Target Name="CreateStagedJunctions">
  <Exec
   Timeout="15000"
   ContinueOnError="true"
   Command='$(MSBuildProjectDirectory)\bin\psexec.exe \\$(WebServer) -n 15 "c:\program files\junction\linkd.exe" $(StagedLocation) $(VersionsLocation)\WebSite_$(Version)'>
  </Exec>
 </Target>

The next questions is why?  By having a directory that contains different versions of the application and using junctions you can simply change the junction to go between versions.  If there is a problem with a release after it goes into production you can revert back to the previous version by simply changing the junction.  Also by using junctions it makes moving a release to production very clean and fast.  The important thing I protect against when moving from QA to a staging environment is if the application version (folder name) already exist then do not proceed with the deployment/move.  Both production and QA use a specific version of the application out of a “versions” folder.  The last thing I want to happen is to have the staged and production environments pointed at the same version since then staged or production would be pointed at the wrong database.