[FIXED] how to escape double quotes in bash inside jenkins?

Issue

I have a Jenkins step as below.

stage('Initialize Namespace') {
    when {
        expression { params.initNS }
         }
        steps {
          script {
             setBuildStatus(processing_test_context, 'Initializing namespace', 'PENDING');
                 }
                 sh  """ #!/bin/bash
                        
                     set -e
                                
                      namespaces="\${kubectl get namespaces -o jsonpath='{range .items[*]}{.metadata.name}{\"\n\"}{end}'}"
                      echo "\${namespaces}"
                      if [[ \$namespaces =~ \$NAMESPACE ]]
                      then
                      kubectl create namespace $NAMESPACE || true
                      else
                      echo "The namespace already exists. Will be using the same"
                      fi
                     """
         }

How do I store the output of the command kubectl get namespaces -o jsonpath='{range .items[*]}{.metadata.name}{"\n"}{end}' in a variable? Currently, the error I am getting is ${kubectl get namespaces -o jsonpath='{range .items[*]}{.metadata.name}{" "}{end}'}: bad substitution. How do I escape " in the command?

Solution

Here is a working shell block for the script you provided.

sh"""
    #!/bin/bash
    namespaces=\$(kubectl get namespaces -o jsonpath='{range .items[*]}{.metadata.name}{\"\\n\"}{end}')
    
    echo "\$namespaces"
    if [[ \$namespaces =~ \$NAMESPACE ]]
    then
        echo "Creating Namespace"
        kubectl create namespace \$NAMESPACE || true
    else
        echo "The namespace already exists. Will be using the same"
    fi
"""

If you don't need variable substitution(String interpolation) in your sh block you can use 3 single quotes rather than using double quotes which will allow you to get rid of multiple escape characters.

On a different note, the following is a different way to get what you need. Here $NAMESPACE has to be not empty always.

sh'''
    #!/bin/bash
    NS=$(kubectl get namespace $NAMESPACE --ignore-not-found);
    echo $NS
    if [[ -z "$NS" ]]; then
        echo "Creating namespace $NAMESPACE"
        kubectl create namespace $NAMESPACE || true
    else
        echo "The namespace already exists. Will be using the same"
    fi
'''

Answered By - ycr
Answer Checked By - Cary Denson (JavaFixing Admin)