Add SSL certificate to store in docker

Question

I am trying to create a simple docker image that runs .NET Core APIs. The problem is, my environment is behind a proxy with self-signed certificate i.e. not trusted :(

Following is my docker file

## runtime:3.1 does not support certoc or openssl or powershell which forced me to change image to nanoserver-1809
#FROM mcr.microsoft.com/dotnet/core/runtime:3.1

FROM mcr.microsoft.com/dotnet/core/runtime:3.1-nanoserver-1809 
ARG source
ARG BUILD_ENV=development

# Option - 1 
# ADD z-scaler-certificate.crt /usr/local/share/ca-certificates/z-scaler-certificate.crt
# RUN certoc -addstore root /usr/local/share/ca-certificates/z-scaler-certificate.crt

# Option - 2
# RUN powershell IMPORT-CERTIFICATE -FilePath /usr/z-scaler-certificate.crt -CertStoreLocation 'Cert:\\LocalMachine\Root'


# Option - 3
# RUN CERT_DIR=(openssl version -d | cut -f2 -d \")/certs; cp /usr/z-scaler-certificate.crt $CERT_DIR; update-ca-certificates; fi

# Option - 4
ADD z-scaler-certificate.crt /container/cert/path
RUN update-ca-certificates

WORKDIR /app
COPY ${source:-bin/Debug/netcoreapp3.1} .
ENTRYPOINT ["dotnet", "Webjob.dll"]

I tried almost all possible options I could try from internet but all fails with the same error -

executor failed running [cmd /S /C update-ca-certificates]: unable to find user ContainerUser: invalid argument

I need help in figuring out what is that I am doing wrong that the certificate is not being added to the store?

Answer 1

In order to execute admin tasks you should use ContainerAdministrator user

FROM mcr.microsoft.com/dotnet/core/runtime:3.1-nanoserver-1809 
ARG source
ARG BUILD_ENV=development
USER ContainerAdministrator
...

Answer 2

When working with containers, I'd recommend keeping to standard Linux tech unless there is a good reason. This is the most standard option and will work on the MS Debian images:

COPY z-scaler-certificate.crt /usr/local/share/certificates/z-scaler-certificate.crt
RUN update-ca-certificates

I am assuming here that your CRT file is a valid root certificate.