Groovy shell script with a sed command in a Jenkins Pipeline - jenkins

Question

So writing Groovy with basic shell scripts seem to be much more difficult than it really should be.
I have a pipeline that needs to replace an entry in a file after running a packer command. It seems sensible to do this in the same shell script as the packer command as the variables are not available outside of the shell script even when exported.
The problem is that the sed command needs escape upon escape and still doesn't work. So this is what the Jenkins Pipeline Syntax generator suggested:
parallel (
"build my-application" : {
sh '''#!/bin/bash
export PATH=$PATH:~/bin
cd ${WORKSPACE}/platform/packer
packer build -machine-readable template.json | tee packer.out
AMI_APP=$(grep amazon-ebs,artifact,0,id,eu-west-2:ami- packer.out | awk -F: \'{ print $NF }\')
[[ ! ${AMI_APP} ]] && exit 1
sed -i.bak \'s!aws_ami_app = \\".*\\"!aws_ami_app = \\"\'"${AMI_APP}"\'\\"!\' ${WORKSPACE}/platform/terraform/env-${ENV}/env.auto.tfvars
'''
},
"build some-more-apps" : {
sh ''' *** same again different name ***
'''
}
)
What is the correct way to get a variable is a sed command working in a bash script running in groovy?
Any tips for the correct syntax going forward with Jenkins, groovy and bash - any documentation that actually helps?
EDIT
The original sed command that is running in a Jenkins Job shell is:
sed -i.bak 's!aws_ami_app = \".*\"!aws_ami_app = \"'"${AMI_APP}"'\"!' ${WORKSPACE}/platform/terraform/env-${ENV}/env.auto.tfvars

Answer 1

Because you put the shell script inside ''' which won't trigger Groovy String interpolation.
So you no need to escape any character, write the script as when you typing in Shell cmd window.
Below is example:
sh '''#!/bin/bash +x
echo "aws_ami_app = docker.xy.com/xy-ap123/conn:7et45u.1.23" > test.txt
echo "cpu = 512" >> test.txt
cat test.txt
AMI_APP=docker.xy.com/xy-ap123/conn:7et45u.1.25
sed -i 's,aws_ami_app.*,aws_ami_app = '"$AMI_APP"',' test.txt
cat test.txt
'''
Output in jenkins console:
[Pipeline] sh
[poc] Running shell script
aws_ami_app = docker.xy.com/xy-ap123/conn:7et45u.1.23
cpu = 512
aws_ami_app = docker.xy.com/xy-ap123/conn:7et45u.1.25
cpu = 512