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'

Answer 4

This worked for me:

USER ContainerAdministrator
RUN setx /M PATH "%PATH%;C:/your/path"
USER ContainerUser

As seen in the .net sdk Dockerfile: https://github.com/dotnet/dotnet-docker/blob/20ea9f045a8eacef3fc33d41d58151d793f0cf36/2.1/sdk/nanoserver-1909/amd64/Dockerfile#L28-L29

Answer 5

Despite all previous answers, I've faced an issue in some environments. Basically on a custom local test environment the setx using the %PATH%;C:\foo\bar way works even when the folder has spaces like C:\Program Files. That though didn't work when trying it on our production environment. Checking what Microsoft do when they install the base packages on their own images it turns out a better and more reliable way is to use the command this way:

RUN setx /M PATH $(${Env:PATH} + \";${Env:ProgramFiles(x86)}\foo\bar\")

This way docker will be able to get the proper paths and properly update the PATH data.

Edit: I've fixed the missing trailing \ in the command, thanks to Robin Ding :)

Answer 6

The following works for me in nanoserver-1809 (from this GitHub issue):

ENV PATH="$WindowsPATH;C:\Foo\bin"

Answer 7

My answer is similar to mirsik's but has no need for a separate script. Just put this in your Dockerfile

RUN $env:PATH = 'C:\Foo\bin;{0}' -f $env:PATH ; \
[Environment]::SetEnvironmentVariable('PATH', $env:PATH, [EnvironmentVariableTarget]::Machine)

Answer 8

The below commands worked for me in a Dockerfile with the base image mcr.microsoft.com/windows/servercore:ltsc2019.

(My scenario was to set Java in the PATH. It works even if there are spaces in the path)

(Make sure to update JAVA_HOME environment variable, with your application/tool)

ENV JAVA_HOME="C:\Program Files\Java\jdk-17"

RUN $newPath = ('{0}\bin;{1}' -f $env:JAVA_HOME, $env:PATH); \
     [Environment]::SetEnvironmentVariable('PATH', $newPath, [EnvironmentVariableTarget]::Machine)

CMD ["java", "--version"]

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On a side note, I did get errors like below when trying some of the other answers here (for reasons like - there were spaces in the path, or, Env variable ${Env:ProgramFiles} was not getting resolved properly, etc.)

• The term 'C:\Program' is not recognized as the name of a cmdlet.
• Unexpected token '\Java\jdk-17\bin' in expression or statement.