Adding Docker support to a ASP.NET Application - asp.net-mvc

Question

I'm working on adding Docker support to an established asp application that has been working great. I was hoping to leverage VS2017 Docker features and functionality by just hitting "add Docker support" and seeing what that "F5 experience" would be like. As luck would have it I was immediately plagued with errors that are a bit cryptic
1>------ Build started: Project: docker-compose, Configuration: Release Any CPU ------
1>C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\MSBuild\Sdks\Microsoft.Docker.Sdk\build\Microsoft.Docker.targets(80,5): error MSB4018: The "ResolveProjectInputAndOutput" task failed unexpectedly.
1>C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\MSBuild\Sdks\Microsoft.Docker.Sdk\build\Microsoft.Docker.targets(80,5): error MSB4018: System.ArgumentNullException: Value cannot be null.
1>C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\MSBuild\Sdks\Microsoft.Docker.Sdk\build\Microsoft.Docker.targets(80,5): error MSB4018: Parameter name: path1
1>C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\MSBuild\Sdks\Microsoft.Docker.Sdk\build\Microsoft.Docker.targets(80,5): error MSB4018: at System.IO.Path.Combine(String path1, String path2)
1>C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\MSBuild\Sdks\Microsoft.Docker.Sdk\build\Microsoft.Docker.targets(80,5): error MSB4018: at Microsoft.Docker.BuildTasks.ResolveProjectInputAndOutput.ResolveRelativeOutputAssemblyPath(TargetOS targetOS, TargetFramework targetFramework, DockerDevelopmentMode developmentMode)
1>C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\MSBuild\Sdks\Microsoft.Docker.Sdk\build\Microsoft.Docker.targets(80,5): error MSB4018: at Microsoft.Docker.BuildTasks.ResolveProjectInputAndOutput.Execute()
1>C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\MSBuild\Sdks\Microsoft.Docker.Sdk\build\Microsoft.Docker.targets(80,5): error MSB4018: at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute()
1>C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\MSBuild\Sdks\Microsoft.Docker.Sdk\build\Microsoft.Docker.targets(80,5): error MSB4018: at Microsoft.Build.BackEnd.TaskBuilder.<ExecuteInstantiatedTask>d__26.MoveNext()
I popped over to the file in question and it's specifically an issue here:
<Target Name="DockerResolveProjectInputAndOutput">
<ResolveProjectInputAndOutput ProjectDirectory="$(MSBuildProjectDirectory)" DockerComposeProjectPath="$(DockerComposeProjectPath)" OutputPath="$(OutputPath)" References="#(Reference)" TargetFileName="$(TargetFileName)" TargetPath="$(TargetPath)" />
</Target>
So I took a peak in the proj file to see if there are any Docker specific issues that can be found. I only found one reference here:
<DockerComposeProjectPath>..\docker-compose.dcproj</DockerComposeProjectPath>
It seems like some configuration hasn't been properly done and it's causing this issue, but haven't had much luck figuring out what/where it would be.

Answer 1

In my case the issue was this: We had a bunch of configurations (Dev, Test, Beta, Prod, Debug, and Release). But, in the project file of the app I was trying to add container support to we didn't have a <PropertyGroup> section for Debug. That section is where the OutputPath is.
Oddly, I got the error even when running in the Dev config.
<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
<PlatformTarget>AnyCPU</PlatformTarget>
<DebugSymbols>true</DebugSymbols>
<DebugType>full</DebugType>
<Optimize>false</Optimize>
<OutputPath>bin\Dev\</OutputPath>
<DefineConstants>DEBUG;TRACE</DefineConstants>
<ErrorReport>prompt</ErrorReport>
<WarningLevel>4</WarningLevel>
<Prefer32Bit>false</Prefer32Bit>
</PropertyGroup>