在微軟官方Asp.net Core runtime image裡安裝powershell

微軟官方 asp.net core 的image 其實是base 在 nano server上(https://github.com/dotnet/dotnet-docker/blob/master/2.2/runtime/nanoserver-1809/amd64/Dockerfile)

而nano server 為了縮小體積早就己經移除powershell。但是powershell是個好東西，沒有powershell對我們要做一些客製的行為很麻煩，所以才會想怎麼才能加回來。

其實也沒什麼密訣，現在微軟都把官方image的DockerFile 都放在Github上了，找到官方powershell image 的 Github，看一下人家怎麼做照做就是了

https://github.com/PowerShell/PowerShell-Docker/blob/master/release/stable/nanoserver/docker/Dockerfile

原理就是先找一個有powershell的image ，下載powershell core (註)裝起來後再Copy到 nano server 上

以下是我的DockerFile

# escape=`

FROM mcr.microsoft.com/windows/servercore:ltsc2019 AS installer-env

ARG PS_VERSION=6.2.0
ARG PS_PACKAGE_URL=https://github.com/PowerShell/PowerShell/releases/download/v${PS_VERSION}/PowerShell-${PS_VERSION}-win-x64.zip

SHELL ["C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe", "-command"]

ARG PS_PACKAGE_URL_BASE64

RUN Write-host "Verifying valid Version..."; `
    if (!($env:PS_VERSION -match '^\d+\.\d+\.\d+(-\w+(\.\d+)?)?$' )) { `
        throw ('PS_Version ({0}) must match the regex "^\d+\.\d+\.\d+(-\w+(\.\d+)?)?$"' -f $env:PS_VERSION) `
    } `
    $ProgressPreference = 'SilentlyContinue'; `
    if($env:PS_PACKAGE_URL_BASE64){ `
        Write-host "decoding: $env:PS_PACKAGE_URL_BASE64" ;`
        $url = [System.Text.Encoding]::Unicode.GetString([System.Convert]::FromBase64String($env:PS_PACKAGE_URL_BASE64)) `
    } else { `
        Write-host "using url: $env:PS_PACKAGE_URL" ;`
        $url = $env:PS_PACKAGE_URL `
    } `
    Write-host "downloading: $url"; `
    [Net.ServicePointManager]::SecurityProtocol = [Net.ServicePointManager]::SecurityProtocol -bor [Net.SecurityProtocolType]::Tls12; `
    Invoke-WebRequest -Uri $url -outfile /powershell.zip -verbose; `
    Expand-Archive powershell.zip -DestinationPath  \PowerShell

# 裝到asp.net core 2.2 runtime 的 image上
FROM mcr.microsoft.com/dotnet/core/aspnet:2.2     

# Copy PowerShell Core from the installer container
ENV ProgramFiles="C:\Program Files" `
    # set a fixed location for the Module analysis cache
    LOCALAPPDATA="C:\Users\ContainerAdministrator\AppData\Local" `
    PSModuleAnalysisCachePath="$LOCALAPPDATA\Microsoft\Windows\PowerShell\docker\ModuleAnalysisCache" `
    # Persist %PSCORE% ENV variable for user convenience
    PSCORE="$ProgramFiles\PowerShell\pwsh.exe"

# Copy PowerShell Core from the installer container
COPY --from=installer-env ["\\PowerShell\\", "$ProgramFiles\\PowerShell\\latest"]

# Set the path 這裡要注意一下，setx /M 需要管理者的權限，
# 但原本的身分是ContainerUser，所以需要先切換身分到ContainerAdministrator ，設完再切回來

USER ContainerAdministrator
RUN setx /M PATH "%ProgramFiles%\PowerShell\latest;%PATH%;"
USER ContainerUser

# intialize powershell module cache
RUN pwsh `
        -NoLogo `
        -NoProfile `
        -Command " `
          $stopTime = (get-date).AddMinutes(15); `
          $ErrorActionPreference = 'Stop' ; `
          $ProgressPreference = 'SilentlyContinue' ; `
          while(!(Test-Path -Path $env:PSModuleAnalysisCachePath)) {  `
            Write-Host "'Waiting for $env:PSModuleAnalysisCachePath'" ; `
            if((get-date) -gt $stopTime) { throw 'timout expired'} `
            Start-Sleep -Seconds 6 ; `
          }"

P.S. 新版的powershell ，己經可以跨平台了，並且改名叫 powershell core 了，而且執行檔名稱也改叫 pwsh.exe，不再是 powershell.exe