Merge pull request #127 from StefanScherer/packer-validate-in-docker

Run packer validate in Windows container

Dockerfile

+FROM mcr.microsoft.com/windows-insider:10.0.17744.1001 AS makeiso
+WORKDIR C:/source
+COPY . .
+RUN powershell -NoProfile -ExecutionPolicy unrestricted -file make_unattend_iso.ps1
+
+FROM mcr.microsoft.com/windowsservercore-insider:10.0.17744.1001
+ENV chocolateyUseWindowsCompression false
+
+RUN powershell -NoProfile -ExecutionPolicy unrestricted -Command \
+    iex ((new-object net.webclient).DownloadString('https://chocolatey.org/install.ps1')); \
+    choco feature disable --name showDownloadProgress
+RUN choco install -y packer
+RUN powershell -Command Install-WindowsFeature Hyper-V-PowerShell
+COPY --from=makeiso C:/source C:/source
+WORKDIR C:/source
+RUN powershell -File test.ps1

README-dockerfile.md

+You may wonder what's this `Dockerfile` for. I have tested the Windows Server 2019 insider 17744 build
+to see if I can run the `test.ps1` script that checks all packer templates with `packer validate` in a Windows container.
+
+```
+docker build -t packervalidate .
+```
+
+If the Docker image can be built then all packer templates have no errors.