How to load PowerShell Module from custom script on vNext build agent?

Question

I am using the standard TFS vNext build step to execute a PowerShell script. Inside the script I am trying to take advantage of some of the functions within the standard TFS Agent modules.

Listed here: http://blog.majcica.com/2015/11/14/available-modules-for-tfs-2015-build-tasks/

I have seen the following two lines in many PowerShell scripts found in the build steps:

Import-Module "Microsoft.TeamFoundation.DistributedTask.Task.Internal"
Import-Module "Microsoft.TeamFoundation.DistributedTask.Task.Common"

I have tried to use the same lines in my script, however I get the error:

VERBOSE: Loading module from path 
'C:\TFS2015-Agent\Agent1\agent\agent\worker\Modules\Microsoft.TeamFoundation.DistributedTask.Task.Common\Microsoft.TeamFoundation.DistributedTask.Task.Common.dll'.
Import-Module : Could not load file or assembly 'Microsoft.TeamFoundation.DistributedTask.Agent.Interfaces, Version=14.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. 
The system cannot find the file specified.
At C:\tfsVnBw1\3\s\Configuration\BuildScripts\CommonFunctions.ps1:25 char:5
+ Import-Module "Microsoft.TeamFoundation.DistributedTask.Task.Common" - Error ... + CategoryInfo : NotSpecified: (:) [Import-Module], FileNotFoundException + FullyQualifiedErrorId : System.IO.FileNotFoundException,Microsoft.PowerShell.Commands.ImportModuleCommand

If I try not to import, it writes something like:

The 'Find-Files' command was found in the module 'Microsoft.TeamFoundation.DistributedTask.Task.Common', 
but the module could not be loaded. For more information, run 'Import-Module Microsoft.TeamFoundation.DistributedTask.Task.Common'. 
At C:\tfsVnBw1\3\s\Configuration\BuildScripts\CommonFunctions.ps1:71 char:16
+ $files = @(FindFiles $filePattern)
+ ~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : ObjectNotFound: (Find-Files:String) [FindFiles], CommandNotFoundException + FullyQualifiedErrorId : CouldNotAutoloadMatchingModule

Is it not possible to use the Modules from 'normal' PowerShell scripts and not only from PowerShell scripts registered as an actual build step?

Answer 1

Try to specify build agent’s module path, such as:

 # Import the Task.Common and Task.Internal dll that has all the cmdlets we need for Build
$agentWorkerModulesPathRoot = "$($env:AGENT_HOMEDIRECTORY)\agent\worker"
$agentDistributedTaskInterfacesModulePath = "$agentWorkerModulesPathRoot\Microsoft.TeamFoundation.DistributedTask.Agent.Interfaces.dll"
$agentWorkerModulesPath = "$($env:AGENT_HOMEDIRECTORY)\agent\worker\Modules"
$agentDistributedTaskCommonModulePath = "$agentWorkerModulesPath\Microsoft.TeamFoundation.DistributedTask.Task.Common\Microsoft.TeamFoundation.DistributedTask.Task.Common.dll"

Write-Host "Importing VSTS Module $agentDistributedTaskInterfacesModulePath"
Import-Module $agentDistributedTaskInterfacesModulePath
Write-Host "Importing VSTS Module $agentDistributedTaskCommonModulePath"
Import-Module $agentDistributedTaskCommonModulePath

Answer 2

Is it not possible to use the Modules from 'normal' PowerShell scripts and not only from PowerShell scripts registered as an actual build step?

It is possible to have a powershell script in build step reference a module. I prefer to use the inline powershell task as it means I dont have to go through the rigmarole of gated checkin just to change the way the code is packaged. I use it quite often to do things like...

• download a common assembly versioning ps1 script from a shared project in TFVC and execute it to stamp assemblies, nuget packages, etc with the build number.
• change the build number
• Save-Module for a module in a private PS repository, and include it in an artifact (install helpers)
• Save-Module again to a temp folder, then import the module and use it to do something to the code being built.
• Generate release notes or similar docs

... but you can use the regular "Run a powershell script" to do all these too.

Perhaps simpler though is to put the module in the path and update powershell if its < 5.1, If you have powershell 3 or later on the build server, and the module is already installed on the server and in the agent account's $PSModulePath, then you dont even need to Import -Module, you can invoke the commands in that module directly.