Jenkins pipeline (parallel && dynamically)? - jenkins

Question

Question
I have simple parallel pipeline (see code) which I use together with Jenkins 2.89.2. Additionally I use parameters and now want to be able to in-/decrease the number of deployVM A..Z stages automatically by providing the parameter before job execution.
How can I dynamically build my pipeline by providing a parameter?
Researched so far:
Jenkins pipeline script created dynamically - Not getting this to work with my Jenkins version
Can I create dynamically stages in a Jenkins pipeline? - Not working either
Code
The pseudo code of what I want - dynamic generation:
pipeline {
agent any
parameters {
string(name: 'countTotal', defaultValue: '3')
}
stages {
stage('deployVM') {
def list = [:]
for(int i = 0; i < countTotal.toInteger; i++) {
list += stage("deployVM ${i}") {
steps {
script {
sh "echo p1; sleep 12s; echo phase${i}"
}
}
}
}
failFast true
parallel list
}
}
}
The code I have so far - executes parallel but is static:
pipeline {
agent any
stages {
stage('deployVM') {
failFast true
parallel {
stage('deployVM A') {
steps {
script {
sh "echo p1; sleep 12s; echo phase1"
}
}
}
stage('deployVM B') {
steps {
script {
sh "echo p1; sleep 20s; echo phase2"
}
}
}
}
}
}
}

Answer 1

Although the question assumes using declarative pipeline I would suggest to use scripted pipeline because it's way more flexible.
Your task can be accomplished this way
properties([
parameters([
string(name: 'countTotal', defaultValue: '3')
])
])
def stages = [failFast: true]
for (int i = 0; i < params.countTotal.toInteger(); i++) {
def vmNumber = i //alias the loop variable to refer it in the closure
stages["deployVM ${vmNumber}"] = {
stage("deployVM ${vmNumber}") {
sh "echo p1; sleep 12s; echo phase${vmNumber}"
}
}
}
node() {
parallel stages
}
Also take a look at snippet generator which allows you to generate some scripted pipeline code.

Answer 2

Using Declarative pipeline also you can achieve this.
Follow my answer HERE
In above link answer I have used Var.collectEntries but map also can be used.

Answer 3

#Vitalii
I wrote similiar code piece, but unfoutunelty, all three element been loopped all shows the last one, not sure if it had something to do with groovy / jenkinsfile itself, that some clouse / reference went break with wrong usage
my purpose is to distribute tasks to specific work nodes
node_candicates = ["worker-1", "worder-2", "worker-3"]
def jobs = [:]
for (node_name in node_candidates){
jobs["run on $node_name"] = { // good
stage("run on $node_name"){ // all show the third
node(node_name){ // all show the third
print "on $node_name"
sh "hostname"
}
}
}
}
parallel jobs
it went totally Ok if I expand / explain the loop, instead of loop over it, like
parallel worker_1: {
stage("worker_1"){
node("worker_1"){
sh """hostname ; pwd """
print "on worker_1"
}
}
}, worker_2: {
stage("worker_2"){
node("worker_2"){
sh """hostname ; pwd """
print "on worker_2"
}
}
}, worker_3: {
stage("worker_3"){
node("worker_3"){
sh """hostname ; pwd """
print "on worker_3"
}
}
}