To make sure we can use PowerShell Core within the entrypoint script, we also need to do some preparation work within the Dockerfile itself. LABEL "com.github.actions.icon" = "code" LABEL "com.github.actions.color" = "red" LABEL "repository" = "https://github.com/dend/blog" LABEL "homepage" = "https://den.dev" LABEL "maintainer" = "Den" RUN apt-get update \ && apt-get install wget -y \ && wget -q https://packages.microsoft.com/config/ubuntu/18.04/packages-microsoft-prod.deb \ && dpkg -i packages-microsoft-prod.deb \ && apt-get update \ && apt-get install -y powershell ADD entrypoint.ps1 /entrypoint.ps1 ENTRYPOINT [ "pwsh" , "/entrypoint.ps1" ] Notice that compared to standard GitHub Actions examples, I’ve just replaced the bash script with the PowerShell script.