Docker image not working

PowerShell Universal
39

Our docker build is super simple. No buildx. Our dockerfile is:

# Docker image file that describes an Ubuntu18.04 image with PowerShell installed from Microsoft APT Repo
ARG fromTag=ubuntu-20.04
ARG imageRepo=mcr.microsoft.com/powershell
FROM ${imageRepo}:${fromTag} AS installer-env

ARG VERSION=1.3.1
ARG PACKAGE_URL=https://imsreleases.blob.core.windows.net/universal/production/${VERSION}/Universal.linux-x64.${VERSION}.zip
ARG DEBIAN_FRONTEND=noninteractive 

# Install dependencies and clean up
RUN apt-get update \
    && apt-get install -y apt-utils 2>&1 | grep -v "debconf: delaying package configuration, since apt-utils is not installed" \
    && apt-get install --no-install-recommends -y \
    # curl is required to grab the Linux package
    curl \
    # less is required for help in powershell
    less \
    # requied to setup the locale
    locales \
    # required for SSL
    ca-certificates \
    gss-ntlmssp \
    # PowerShell remoting over SSH dependencies
    openssh-client \
    unzip \
    libc6-dev \
    tzdata \
    # Download the Linux package and save it
    && echo ${PACKAGE_URL} \
    && curl -sSL ${PACKAGE_URL} -o /tmp/universal.zip \
    && unzip /tmp/universal.zip -d ./home/Universal || : \
    # remove powershell package
    && rm /tmp/universal.zip \
    && chmod +x ./home/Universal/Universal.Server

# Use PowerShell as the default shell
# Use array to avoid Docker prepending /bin/sh -c
WORKDIR /home
EXPOSE 5000
ENTRYPOINT ["./Universal/Universal.Server"]

The build command is.

param($Version = (Get-Content "$PSScriptRoot/../../../version.txt" -Raw).Trim())
Set-Location $PSScriptRoot
docker build . --tag=universal --build-arg VERSION=$Version

We effectively download the specified version of PSU, extract it into the container and then setup a couple settings like expose and entrypoint.