Jenkins workflow environment variables causing a failure

Question

For this very simple workflow:

env.FOO = 42
node {
  sh "echo $FOO"
}

I get the following error:

Running: End of Workflow
groovy.lang.MissingPropertyException: No such property: FOO for class: WorkflowScript

How do I access environment variables in workflow shell steps?

Answer 1

I had an issue where I needed to mix interpolation. Where part of the script is interpolated before, and part of the script is interpolated during. The trick to to escape the variable(s) you want interpolated during the run with a backslash:

def FOO = 42

node {
  sh """
    BAR = "hello $FOO"
    echo \$BAR
  """
}

So $FOO is expanded before the script runs, and \$BAR is expanded during the script run.

Answer 2

The reason is that with double quotes the string interpolation of Groovy kicks in and looks for a workflow scoped variable of FOO.

To fix use single quotes:

sh 'echo $FOO'

Note also you can use workflow variables in scripts with double quotes:

def FOO = 43

node {
  sh "echo $FOO"
}

This will expand the value of $FOO before the script is run.