Parallel checkout in declarative Jenkins pipeline on multiple nodes - jenkins

Question

I'm developing a declarative Jenkins pipeline for CI builds, triggered from Gitlab. What I have now:
// variable definitions
pipeline {
agent none
parameters {
string(defaultValue: 'develop',
description: 'Commit ID or branch name to build',
name: 'branch',
trim: false)
}
stages {
stage('Checkout') {
parallel {
stage ('Windows') {
agent {
label 'build' && 'windows'
}
steps {
script {
def checkout_ext = [[$class: 'CleanCheckout'],
[$class: 'CleanBeforeCheckout']] // calls git clean -fdx and git reset --hard
if (env.gitlabActionType == "MERGE"){
checkout_ext.add([$class: 'PreBuildMerge',
options: [ mergeRemote: "origin",
mergeTarget: "${env.gitlabTargetBranch}"]])
}
}
checkout([
$class: 'GitSCM',
branches: [[name: "${params.branch}"]],
userRemoteConfigs: [[ url: "${git_url}", credentialsId: "${git_credentials_id}" ]],
extensions: checkout_ext
])
}
}
stage('Linux') {
agent {
label 'build' && 'linux'
}
steps {
script {
def checkout_ext = [[$class: 'CleanCheckout'],
[$class: 'CleanBeforeCheckout']] // calls git clean -fdx and git reset --hard
if (env.gitlabActionType == "MERGE"){
checkout_ext.add([$class: 'PreBuildMerge',
options: [ mergeRemote: "origin",
mergeTarget: "${env.gitlabTargetBranch}"]])
}
}
checkout([
$class: 'GitSCM',
branches: [[name: "${params.branch}"]],
userRemoteConfigs: [[ url: "${git_url}", credentialsId: "${git_credentials_id}"]],
extensions: checkout_ext
])
}
}
}
}
}
}
Checkout stage is somewhat complex. If gitlabActionType is MERGE, then first try to merge into a target branch, to make sure that merge request does not break anything in it.
This code is the same for both OSes. I'd like to avoid code duplication, but cannot figure out correct syntax for that.
I have tried moving definition of checkout steps to the global variable, but have got syntax errors.
def checkout_step = {
script {
...
}
checkout (... )
}
pipeline {
...
stages {
stage('Checkout') {
parallel {
stage ('Windows') {
agent {
label 'build' && 'windows'
}
steps {
checkout_step
}
}
stage ('Linux') {
agent {
label 'build' && 'linux'
}
steps {
checkout_step
}
}
}
}
}
}
If add steps, there's also an error:
def checkout_step = steps {
script {
...
}
checkout (... )
}
pipeline {
...
stages {
stage('Checkout') {
parallel {
stage ('Windows') {
agent {
label 'build' && 'windows'
}
checkout_step
}
stage ('Linux') {
agent {
label 'build' && 'linux'
}
checkout_step
}
}
}
}
}

Answer 1

Have found solution here
git_url = "git#gitserver.corp.com:group/repo.git"
git_credentials_id = 'aaaaaaa-bbbb-cccc-dddd-eefefefefef'
def checkout_tasks(os_labels) {
tasks = [:]
for (int i = 0; i < os_labels.size(); i++) {
def os = os_labels[i]
tasks["${os}"] = {
node("build && ${os}"){
def checkout_ext = [[$class: 'CleanCheckout'], [$class: 'CleanBeforeCheckout']] // calls git clean -fdx and git reset --hard
if (env.gitlabActionType == "MERGE"){
checkout_ext.add([
$class: 'PreBuildMerge',
options: [
mergeRemote: "origin",
mergeTarget: "${env.gitlabTargetBranch}"
]
])
/* using this extension requires .gitconfig with section [user for Jenkins]
Example
[user]
email = jenkins#builder
name = Jenkins
*/
}
checkout([
$class: 'GitSCM',
branches: [[name: "${params.branch}"]],
userRemoteConfigs: [[
url: "${git_url}",
credentialsId: "${git_credentials_id}"
]],
extensions: checkout_ext
])
}
}
}
return tasks
}
pipeline {
agent none
parameters {
string(defaultValue: 'develop',
description: 'Commit ID or branch name to build',
name: 'branch',
trim: false)
}
stages {
stage('Checkout') {
steps {
script {
def OSes = ["windows", "linux"]
parallel checkout_tasks(OSes)
}
}
}
}
}
It is important also to declare git_url and git_credentials_id without def, so that functions can read them.
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