How to capture a Cake build failure within an Azure DevOps task? - powershell

Question

For the reasons that are beyond the scope of this discussion, I have the following Azure DevOps setup which is being used to build some .NET library:
An Azure DevOps Powershell task:
- task: PowerShell#2
displayName: 'My task'
inputs:
targetType: filePath
filePath: 'build_cake.ps1'
arguments: '<my arguments>'
The build_cake.ps1 script, executed by the DevOps task, which invokes Cake passing it the build.cake script:
try {
Invoke-Expression "& <invoke Cake with build.cake>"
}
catch {
exit 1;
}
The build.cakescript which sets up some parameters and calls Build.RunDotNetCore:
Build.SetParameters(...);
Build.RunDotNetCore();
The RunDotNetCore call internally executes the dotnet build command. When that build fails for whatever reason, the error is not captured and/or propagated all the way back, so the Azure DevOps task (1) still happily reports successful execution.
I'm looking for a way to fix this.
At this point I'm not even sure whether the issue/solution is on the Cake side or on the Powershell side.
As my example shows, I have tried to wrap Invoke-Expression in a try/catch block but that didn't fix anything. I have also tried checking the $LASTEXITCODE code right after the Invoke-Expression call. (I guess $LASTEXITCODE is not supposed to be set anyway, since I'm invoking an external application and not a commandlet.)
To be clear, I'm not looking for an alternative solution (for example, to replace the existing setup with an equivalent Cake Azure DevOps task). I need to fix this particular setup with minimal changes, if possible.

Answer 1

The boostrapper I'm using looks like this and is confirmed working with Azure DevOps
$ErrorActionPreference = 'Stop'
dotnet tool restore
if ($LASTEXITCODE -ne 0) { exit $LASTEXITCODE }
dotnet cake #args
if ($LASTEXITCODE -ne 0) { exit $LASTEXITCODE }
Above assumes your using a .NET tool manifest to version Cake, if you have Cake installed already on the agent you can skip the dotnet tool restore part.
Versioning Cake with a tool-manifest is preferred though as that ensures same version of Cake used locally and remote.
Installing Cake via tool manifest is done using dotnet cli in your repository root.
dotnet new tool-manifest
dotnet tool install Cake.Tool
and then add & commit in the .config/dotnet-tools.json file created.
Then when cloning the repo it's
dotnet tool restore
dotnet cake
And it'll fetch and execute the right version of Cake.