Issue porting Jenkinsfile scripted to declarative withEnv{} => environment{} - jenkins

Question

I have issue porting scripted to declarative pipeline. I used to have in scripted:
//Scripted
def myEnv = [:]
stage ('Prepare my env') { [...] myEnv = ... }
stage ('Fancy stuff') {
node() {
withEnv(myEnv) {
// here use what is defined in myEnv
}
}
stage ('Fancy stuff2') {
node() {
withEnv(myEnv) {
// here use what is defined in myEnv
} }
}
and now in declarative I would like to have
//Declarative
def myEnv = [:]
pipeline {
agent none
stage('Prepare my env') {
steps {
script {
[...]
myEnv = ...
}
}
}
stages {
environment { myEnv }
stage('Fancy stuff') {
[...]
}
stage('Fancy stuff2') {
[...]
}
} }
when I try to run this, it fails withEnv
org.codehaus.groovy.control.MultipleCompilationErrorsException:
startup failed: WorkflowScript: xx: "myEnv" is not a valid environment
expression. Use "key = value" pairs with valid Java/shell keys.
Fair enough.
What should I do to be able to use declarative environment { } to avoid using withEnv(myEnv) one in every further steps?

Answer 1

it seems that the part you are missing is the usage of environment clause.
Instead of
environment { myEnv }
It should be
environment { myEnvVal = myEnv }
Just as the error method mentions this should be key = value pair.

Answer 2

Your issue comes from the type of your variable myEnv. You define it as a map when you do def myEnv = [:].
So it works with withEnv that takes a map as parameter but it does not work with environment {...} that takes only "key = value" statements.
The solution depends on how you add environment variables contained in myEnv.
The simplest way is using environment directive by listing all the key/values contained in your former variable myEnv:
pipeline{
agent none
environment {
test1 = 'test-1'
test2 = 'test-2'
}
stages{
stage('Fancy stuff'){
steps{
echo "${test1}"
}
}
stage('Fancy stuff2'){
steps{
echo "${test2}"
}
}
}
}
But you also do it the scripted way :
pipeline{
agent none
stages{
stage('Prepare my env') {
steps {
script {
def test = []
for (int i = 1; i < 3; ++i) {
test[i] = 'test-' + i.toString()
}
test1 = test[1]
test2 = test[2]
}
}
}
stage('Fancy stuff'){
steps{
echo "${test1}"
}
}
stage('Fancy stuff2'){
steps{
echo "${test2}"
}
}
}
}