Appending to PATH in a Windows Docker container

Question

I need to append to the PATH within a Windows Docker container, and I've tried many permutations.

ENV PATH=%PATH%;C:\\Foo\\bin
ENV PATH=$PATH;C:\\Foo\\bin
ENV PATH="%PATH%;C:\Foo\bin"
ENV PATH="$PATH;C:\Foo\bin"
RUN "set PATH=%PATH%;C:\Foo\bin"

None of these work: they don't evaluate the preexisting PATH variable.

What is the right syntax to append to the PATH? Can I even append to the PATH inside Docker? (I can on similar Linux containers)

Answer 1

Unfortunately ENV won't work, because windows environment variable work a little differently than linux. more info

As of now the only way to do this is through RUN

But you don't need to create a separate file to do this. This can be done by the following much simpler one line command:

RUN setx path "%path%;C:\Foo\bin"

Answer 2

You can set environment variables permanently in the container using a powershell script.

Create a powershell script in yout docker context (e.g. setpath.ps1 ) containing this:

[Environment]::SetEnvironmentVariable("Path", $env:Path + ";C:\Foo\bin", [EnvironmentVariableTarget]::Machine)

Add this script to your container dockerfile and RUN the script. Add something like this to your dockerfile:

ADD ./setpath.ps1 c:/MyScripts/setpath.ps1
RUN powershell -Command c:\MyScripts\setpath.ps1

Answer 3

[Environment]::SetEnvironmentVariable is a good way, but will not work in nanoserver. The best choice is:

RUN setx path '%path%;C:\Foo\bin'