DockerFile executing powershell file cannot be found - docker

Question

I'm attempting to get an asp.net MVC application running using docker for windows. Which I've configured to use windows containers.
I'm using VS2017 to add docker support which generates the DockerFile and the docker-compose project.
The default DockerFile consists of:
FROM microsoft/aspnet:4.6.2
ARG source
WORKDIR /inetpub/wwwroot
COPY ${source:-obj/Docker/publish} .
Creating an image configured to run IIS with .net 4.6.2
This works fine, however I need to configure SSL. Using this example (https://github.com/MicrosoftDocs/Virtualization-Documentation/blob/live/windows-container-samples/iis-https/Dockerfile) and changing my file to:
FROM microsoft/aspnet:4.6.2
ARG source
WORKDIR /inetpub/wwwroot
COPY ${source:-obj/Docker/publish} .
RUN powershell.exe -Command " \
Import-Module IISAdministration; \
$cert = New-SelfSignedCertificate -DnsName demo.contoso.com -CertStoreLocation cert:\LocalMachine\My; \
$certHash = $cert.GetCertHash(); \
$sm = Get-IISServerManager; \
$sm.Sites[\"Default Web Site\"].Bindings.Add(\"*:443:\", $certHash, \"My\", \"0\"); \
$sm.CommitChanges();"
Works fine. However this is a self-signed cert and I wish to use a cert I copy to the image that I can also install into my cert store on my own machine for it to be trusted.
I've changed the DockerFile to:
FROM microsoft/aspnet:4.6.2
ARG source
WORKDIR /inetpub/wwwroot
COPY ${source:-obj/Docker/publish} .
WORKDIR /
COPY ${source:-server.pfx} ./server.pfx
RUN powershell.exe ls;
RUN powershell.exe -executionpolicy bypass -Command " \
Import-Module WebAdministration; \
$pwd = ConvertTo-SecureString -String \"server\" -Force -AsPlainText; \
Import-PfxCertificate -CertStoreLocation \"cert:\\LocalMachine\\Root\\b455d81e2414ec1da38f4de105b98066506cf86e\" -Password $pwd -FilePath \"c:\\server.pfx\"; \
Import-PfxCertificate -CertStoreLocation \"cert:\\LocalMachine\\My\\b455d81e2414ec1da38f4de105b98066506cf86e\" -Password $pwd -FilePath \"c:\\server.pfx\"; \
$cert = Get-Item "cert:\LocalMachine\My\b455d81e2414ec1da38f4de105b98066506cf86e"; \
New-WebBinding -Name \"Default Web Site\" -Protocol \"https\" -IPAddress \"*\" -Port 443; \
New-Item \"IIS:\\SslBindings\\0.0.0.0!443\" -Value $cert;"
Which feels like it should work. The powershell ls command shows the server.pfx file sitting on the c: drive of the container. However when it runs the powershell command setting up the certificate it errors saying it cannot find the file.
I've also run into issues where I've put the powershell into an actual script file, copied it onto the container, executed it, its all gone through fine but nothing seems to have happened.
If I use this chaps docker hub image it works as expect and he's using an actual powershell file:
https://hub.docker.com/r/rgarita/aspnet-ssl/
https://github.com/rgarita/aspnet-ssl-docker/tree/master/4.6.2
I'm at a bit of a loss with this, not sure if anyone has any ideas or have already gone through pain similar to this?
Thanks in advance,
Jon