.NET Core 2.1 version error with Cake Build 4.0 NuGetRestore and MSBuild actions - powershell

Question

Cake Build 4.0.0 runs NuGetRestore and MSBuild methods by executes MSBuild CLI command. From my understanding, Cake downloads certain version of MSBuild. In my solution, it is mostly .NET Framework, but our testing project is targeting .NET Core 2.1 (we will eventually move our whole project to .NET Core 2.1+ but cannot right now). I am experiencing the following error:
C:\git\OurProduct\PPUXL\tools\.dotnet\sdk\2.1.4\Sdks\Microsoft.NET.Sdk\build\Microsoft.NET.TargetFrameworkInference.targets(135,5): error : The current .NET SDK does not support targeting .NET Core 2.1. Either target .NET Core 2.0 or lower, or use a version of the .NET SDK that supports .NET Core 2.1. [C:\git\OurProduct\PPUXL\src\Portals\Core\OurProduct.Tests\OurProduct.Tests.csproj]
So normally I would download a new SDK, but we are going to run the script on Azure DevOps on a build agent and the SDKs are not part of our workstation but are downloaded and compiled by Cake via the Powershell script we run.
Here is the code the causes the error:
Task("Restore")
.Does(() =>
{
//We need to change this code if we switch from .NET Framework to .NET Core for this project.
NuGetRestore(
solution,
new NuGetRestoreSettings()
{
PackagesDirectory = packagesDirectory
}
);
var projects = GetFiles("./**/*.csproj");
foreach(var project in projects)
{
NuGetRestore(
project,
new NuGetRestoreSettings()
{
PackagesDirectory = packagesDirectory
}
);
}
});
Task("Build")
.Does(() =>
{
MSBuild(
SAMLProject,
new MSBuildSettings()
.SetConfiguration(configuration)
.WithProperty("DeployOnBuild", "true")
.WithProperty("PublishProfile", configuration)
.WithProperty("publishUrl", SAMLDeployDirectory)
.WithProperty("WebPublishMethod", "FileSystem")
);
var projects = GetFiles("./**/*.csproj");
foreach(var project in projects)
{
if(!project.FullPath.Contains("Tests") && !project.FullPath.Contains("SAML"))
{
MSBuild(
project,
new MSBuildSettings()
.SetConfiguration(configuration)
);
}
}
MSBuild(
testProject,
new MSBuildSettings()
.SetConfiguration(configuration)
);
});
I can get prevent the error by doing this:
Task("Restore")
.Does(() =>
{
//We need to change this code if we switch from .NET Framework to .NET Core for this project.
NuGetRestore(
solution,
new NuGetRestoreSettings()
{
PackagesDirectory = packagesDirectory
}
);
var projects = GetFiles("./**/*.csproj");
foreach(var project in projects)
{
if(!project.FullPath.Contains("Tests") && !project.FullPath.Contains("SAML"))
{
NuGetRestore(
project,
new NuGetRestoreSettings()
{
PackagesDirectory = packagesDirectory
}
);
}
}
});
Task("Build")
.Does(() =>
{
MSBuild(
SAMLProject,
new MSBuildSettings()
.SetConfiguration(configuration)
.WithProperty("DeployOnBuild", "true")
.WithProperty("PublishProfile", configuration)
.WithProperty("publishUrl", SAMLDeployDirectory)
.WithProperty("WebPublishMethod", "FileSystem")
);
var projects = GetFiles("./**/*.csproj");
foreach(var project in projects)
{
if(!project.FullPath.Contains("Tests") && !project.FullPath.Contains("SAML"))
{
MSBuild(
project,
new MSBuildSettings()
.SetConfiguration(configuration)
);
}
}
MSBuild(
testProject,
new MSBuildSettings()
.SetConfiguration(configuration)
);
});
How can run the build methods to target the correct .NET Core libraries using Cake? I want the build to all happen within my Powershell script and my Cake script with no environmental influence. Thanks in advance.

Answer 1

Cake doesn't download any tools automatically, it does resolve tools automatically though.
The error would suggest that the machine the build is running on lacks an .NET Core SDK that can build .NET Core 2.1 apps.
You can download an install .NET Core SDK from https://dotnet.microsoft.com/download/dotnet-core/2.1
For Azure DevOps you can use the .NET Core Tool Installer task to ensure
If you want to contain your tools with in repository and not install anything into i.e. program files, then installing SDK using a PowerShell/Bash boostrapper is a way to ensure everyone's gets and uses the same SDK without affecting the rest of the system.
Microsoft provides scripts for obtaining the SDK at
https://dot.net/v1/dotnet-install.ps1
https://dot.net/v1/dotnet-install.sh
Example usage:
dotnet-install.ps1 -Channel 'LTS' -Version '2.1.603' -InstallDir '.\dotnet';
Cake project itself uses this method in it's build.ps1, downloading the SDK version it needs if it's not available on the machine.
If you also want to ensure you're using the downloaded SDK to build your projects, then you can switch from NuGetRestore/MSBuild aliases to
DotNetCoreRestore
DotNetCoreBuild
These aliases will invoke the .NET Core CLI, and if the downloaded .NET COre CLI is first in path or specified on the .NET Core aliases settings ToolPath property, then it'll be the one used. .NET Core SDK can build both .NET Core and .NET Framework projects. I.e. the Cake project achieves this in its in it's build.ps1 by adding the dotnet folder first in path environment variable.