Nix Entry Shell with TTY

[toddpi314]

A major weak spot right now for Windows Containers is the support for a POSIX shell that supports TTY.

Installing a POSIX-compliant runtime and SHELL statement pointing at an installed shell (bash, sh, zsh) doesn't offer TTY and stdout is only capable on docker without the -t option. You essentially have to either issue commands with no stdout or not be able to interact.

Additionally, the Windows Subsystem for Linux doesn't install on containers.

Real world example of why this is important:

Jenkins v2 Swarm can't light up Windows Container support because executors expect to be able to issue the id and cat commands with TTY with build containers

With AWS bringing Windows Containers into Beta (http://docs.aws.amazon.com/AmazonECS/latest/developerguide/ECS_Windows.html), this seems like a huge win for MS to sell Cloud Lic for Jenkins users.

BTW, Fantastic work on this container digest. We have all been cultivating this stuff since last fall, but good to see some MVPs organizing the public effort.

[StefanScherer]

Thanks @toddpi314, my journey with Windows containers began long before I became a MVP.

I agree, a Jenkins swarm working with Windows Containers would help a lot of people. I wonder why they depend on third-party tools like id and cat as they are not part of vanilla Windows. So here the problem begins as neither Cloudbees nor Microsoft really can help to make it work. I only can suggest to start a discussion about removing that dependency in the Jenkins swarm and use Windows native commands instead. Are there any open issues in the Jenkins / Jenkins swarm repos?

I only know these issues arround MSYS / Cygwin:

• MSYS2-based programs don't output anything to console docker/for-win#262
• https://github.com/Alexpux/Cygwin/issues/23
• Git clone does not work in Windows Docker container in mounted host volume folder git-for-windows/git#1007

[toddpi314]

Adding this to the fun: https://issues.jenkins-ci.org/browse/JENKINS-36776

[toddpi314]

I made some progress on this:

1. The Swarm Node Host needs to have basic *nix tools on the path in order for Jenkins Swarm plugin to honor basic pipeline commands. That is, install Cygwin and Git for Windows on the Windows Server 2016 host and export tools to PATH.
   • Run the Swarm Node Plugin with tools setup for at least the git.exe
2. Build a microsoft/windowsservercore container that supports basic *nix operations on the PATH as well. Here is a base image: https://github.com/DeepElement/docker-winservercore-jenkins-pipeline
3. Download sources from SCM, build the workspace container in the Jenkinsfile and attempt to issue a bat command inside of the container.

As Cody D reports on thread https://issues.jenkins-ci.org/browse/JENKINS-36776, step #3 stalls where the BAT command doesn't seem to return anything when Jenkins Pipeline calls --entrypoint cat and expects commands to pipe via TTY.

The good news is this approach makes things get to #3 without alteration to the stock plugins.

Maybe this help us focus on which cat implementation we are using.

[toddpi314]

Here are the sources for how Jenkins expects to interact with the container: https://github.com/jenkinsci/jenkins/blob/d111e2ac1658c8fa5fb768e7d1233613b4b9992d/core/src/main/java/hudson/tasks/BatchFile.java

[StefanScherer]

@toddpi314 have you seen this pull request? jenkinsci/docker-plugin#465

[StefanScherer]

And a very interesting Jenkins setup https://github.com/i-net-software/docker-boxes, with some Windows Docker images as well.

[StefanScherer]

I'll close this issue here as it has to be resolve probably in cygwin / mingw. We have collected a lot of links to other issues to follow the progress there.