How to achive nested parallel in Jenkins declarative pipeline? - jenkins

Question

I have declarative pipeline as below and it runs 2* and 3* stages in parallel, pasted the blue ocean diagram below.
pipeline {
agent { label 'my_node' }
options {
timestamps()
parallelsAlwaysFailFast()
}
stages {
stage('1') {
steps {
script {
step([$class: 'WsCleanup'])
}
}
}
stage('2') {
parallel {
stage("2.1") {
steps {
script {
sh 'echo hi 2.1'
}
}
}
stage("2p") {
steps {
script {
sh 'echo hi 2p'
}
}
}
}
}
stage('3') {
parallel {
stage('3.1') {
steps {
script {
sh """
echo hi 3.1
"""
}
}
}
stage('3.2') {
steps {
script {
sh """
echo "hi 3.2"
"""
}
}
}
}
}
stage('4') {
steps {
script {
sh "echo end"
}
}
}
}
}
But I am looking to run 2p in parallel to 2* and 3*, like shown below, is there a way?
I tried to use paralle under parallel, to start 2p in parallel to 2 and 3, and nested parallel to run 3.1. and 3.2 underneath, but declarative pipeline is not allowing nested parallel.

Answer 1

You can't do this only with Declarative syntax. But you can achieve this with a combination of Scripted and Declarative syntax. One thing to note is, AFAIK there is no visualization support for nested parallel stages as of now. There is a feature request for this here.
Following is a sample pipeline you can use as a reference for your use case.
pipeline {
agent any
options {
timestamps()
parallelsAlwaysFailFast()
}
stages {
stage('1') {
steps {
script {
step([$class: 'WsCleanup'])
}
}
}
stage('2 AND 3') {
steps {
script {
parallel getWrappedStages()
}
}
}
stage('4') {
steps {
script {
sh "echo end"
}
}
}
}
}
def getWrappedStages() {
stages = [:]
stages["Step2.1"] = { stage('2.1') {
sh """
echo hi 2.1
"""
}
parallel parallel3xstages()
}
stages["Step2.p"] = { stage('2.p') {
sh """
echo hi 2.p
"""
}
}
return stages
}
def parallel3xstages() {
stages = [:]
stages["Step3.1"] = { stage('3.1') {
sh """
echo hi 3.1
"""
}
}
stages["Step3.2"] = { stage('3.2') {
sh """
echo hi 3.2
"""
}
}
return stages
}