How to switch user in a Windows container?

How to switch user in a Windows container?

Issue

• execute command whoami in a Windows ServerCore container returns user manager\containeradministrator
• switch user manager\containeradministrator to other user which has the administrator priviledge

Solution

• UAC(User Account Control) service is not available in Windows ServerCore image, so you cannot use built-in administrator user directly. alternatively, you can create an normal user and add it to the administrator group within a Dockerfile.

  FROM mcr.microsoft.com/windows/servercore:ltsc2016
  RUN NET USER sp_farm /add
  RUN NET LOCALGROUP Administrators /add sp_farm
  
  USER sp_farm
  SHELL ["powershell"]
  RUN whoami
  

• Dockerfile testing

  PS C:\Users\Administrator\switchuser> docker images
  REPOSITORY                             TAG                 IMAGE ID            CREATED             SIZE
  switchuser                             latest              90ecd9b64839        39 seconds ago      11.3GB
  mcr.microsoft.com/windows/servercore   ltsc2016            e9d0a8d2fc57        2 weeks ago         11.3GB
  
  PS C:\Users\Administrator> docker run switchuser whoami
  bd76e5fdc8e2\sp_farm
  
  PS C:\Users\Administrator> docker run switchuser net user
  
  User accounts for \\983E494312BA
  
  -------------------------------------------------------------------------------
  Administrator            DefaultAccount           Guest
  sp_farm
  The command completed successfully.