I could not achieve changing the working directory using the suggestion by Vishwas, although I did try creating a Jenkins user inside the container with the same uid as the host. It just didn't work for me. I did however, realize that I didn't actually need to change the directory on the container because the workspace was already in the container.

I'm using the Docker Plugin from CloudBees. After reading their documentation, I realized the workstation folder I thought was on the host machine, was actually in the container. Part of the documentation stated:

The above is a complete Pipeline script. inside will:

1. Automatically grab an agent and a workspace (no extra node block is required).
2. Pull the requested image to the Docker server (if not already cached).
3. Start a container running that image.
4. Mount the Jenkins workspace as a "volume" inside the container, using the same file path.

After seeing item number four, I ran docker container inspect <containerID> and I saw the workspace /home/jenkins/workspace was actually a volume mount that was mapped to the /home/jenkins/workspace on the Docker host machine as well. Using this as my workspace, I was able to build the various applications within the container and then moved the results to a second volume used for application collection later in the pipeline. It's not an exact answer to my original question, but it works!

Use double quotes

dir ("RELEASE/abc/${abc_version}")

in groovy Single quotes are a standard Java String while Double quotes are a templatable String

e.g

a = 10
b = "RELEASE/abc/${a}"
c = 'RELEASE/abc/${a}'
print(b)
print('\n')
print(c)

output will be

RELEASE/abc/10
RELEASE/abc/${a}

You can try it here

You can use the dir step, example:

dir("folder") {
    sh "pwd"
}

The folder can be relative or absolute path.

There are lots of ways to do this. Here are two ways I can think of off the top of my head:

steps {
  println(WORKSPACE)
}

or

steps {
  def foo = sh(script: 'pwd', returnStdout: true)
  println(foo)
}

What you can do is use the dir step, if the directory doesn't exist, then the dir step will create the folders needed once you write a file or similar:

node {
    sh 'ls -l'
    dir ('foo') {
        writeFile file:'dummy', text:''
    }
    sh 'ls -l'
}

The sh steps is just there to show that the folder is created. The downside is that you will have a dummy file in the folder (the dummy write is not necessary if you're going to write other files). If I run this I get the following output:

Started by user jon
[Pipeline] node
Running on master in /var/lib/jenkins/workspace/pl
[Pipeline] {
[Pipeline] sh
[pl] Running shell script
+ ls -l
total 0
[Pipeline] dir
Running in /var/lib/jenkins/workspace/pl/foo
[Pipeline] {
[Pipeline] writeFile
[Pipeline] }
[Pipeline] // dir
[Pipeline] sh
[pl] Running shell script
+ ls -l
total 4
drwxr-xr-x 2 jenkins jenkins 4096 Mar  7 22:06 foo
[Pipeline] }
[Pipeline] // node
[Pipeline] End of Pipeline
Finished: SUCCESS

I ended up with a "prepare project" stage that puts the subdirectory content into the root.

It's also probably a good idea to remove all the root contents (stage "clean") to be absolutely sure there are no leftovers from previous builds.

node {
    def dockerImage

    stage('clean') {
      sh "rm -rf *"
    }

    stage('checkout') {
        checkout scm
    }

    // need to have only 'backend' subdir content on the root level
    stage('prepare project') {
        // The -a option is an improved recursive option, that preserve all file attributes, and also preserve symlinks.
        // The . at end of the source path is a specific cp syntax that allow to copy all files and folders, included hidden ones.
        sh "cp -a ./backend/. ."
        sh "rm -rf ./backend"
        // List the final content
        sh "ls -la"
    }

    stage('build docker image') {
        dockerImage = docker.build("docker-image-name")
    }

    stage('publish docker image') {
        docker.withRegistry('https://my-private-nexus.com', 'some-jenkins-credentials-id') {
            dockerImage.push 'latest'
        }
    }
}

If you want a list of all directories under a specific directory e.g. mydir using Jenkins Utility plugin you can do this:

Assuming mydir is under the current directory:

 dir('mydir') {
   def files = findFiles() 
 
   files.each{ f -> 
      if(f.directory) {
        echo "This is directory: ${f.name} "
      }
   }
 }

Just make sure you do NOT provide glob option. Providing that makes findFiles to return file names only.

More info: https://jenkins.io/doc/pipeline/steps/pipeline-utility-steps/