How to wait for user input in a Declarative Pipeline without blocking a heavyweight executor

Question

I'm rebuilding an existing build pipeline as a jenkins declarative pipeline (multi-branch-pipeline) and have a problem handling build propagation.

After packaging and stashing all relevant files the pipeline is supposed to wait for user input to trigger deployment.

If i just add an input step the current build-node is blocked. As this executor is pretty heavy i would like to move this step to a more lightweight machine.

Initially i did the job as a scripted pipeline and just created two different node('label') blocks. is there a way for me to do something similar with the declarative syntax?

node('spine') {      stage('builder') {         sh 'mvn clean compile'         stash name: 'artifact', includes: 'target/*.war'     } } node('lightweight') {     stage('wait') {         timeout(time:5, unit:'DAYS') {             input message:'Approve deployment?'         }     }     // add deployment stages } 

I tried a couple of things already:

configuring the agent on the top-level and adding an additional agent config to the propagation step, but then i have two executors blocking as the top-level defined build-node is not stopped.

Setting agent none on top-level and configuring the agents per step. then the git checkout is not present on the first node.

EDIT 1

i reconfigured my pipeline following you advice, it currently looks like this:

pipeline { agent none tools {     maven 'M3' } stages {     stage('Build') {         agent { label 'spine' }         steps {             checkout scm // needed, otherwise the workspace on the first step is empty             sh "mvn clean compile"         }     }     stage('Test') {         agent { label 'spine' }         steps {             sh "mvn verify" // fails because the workspace is empty aggain             junit '**/target/surefire-reports/TEST-*.xml'         }     } } } 

this build will fail because the workspace does not carry over between steps as they dont run on the same executor.

EDIT 2

apparently sometimes the steps run on the same executor and sometimes don't. (we spawn build slaves on our mesos/dcos cluster on demand, so changing the executor mid build would be a problem)

I expected jenkins to just run with the current executor as long as the label in the agent definition does not change.

Answer 1

See best practice 7: Don’t: Use input within a node block. In a declarative pipeline, the node selection is done through the agent directive.

The documentation here describes how you can define none for the pipline and then use a stage-level agent directive to run the stages on the required nodes. I tried the opposite too (define a global agent on some node and then define none on stage-level for the input), but that doesn't work. If the pipeline allocated a slave, you can't release the slave for one or more specific stages.

This is the structure of our pipeline:

pipeline {   agent none   stages {     stage('Build') {       agent { label 'yona' }       steps {         ...       }     }     stage('Decide tag on Docker Hub') {       agent none       steps {         script {           env.TAG_ON_DOCKER_HUB = input message: 'User input required',               parameters: [choice(name: 'Tag on Docker Hub', choices: 'no\nyes', description: 'Choose "yes" if you want to deploy this build')]         }       }     }     stage('Tag on Docker Hub') {       agent { label 'yona' }       when {         environment name: 'TAG_ON_DOCKER_HUB', value: 'yes'       }       steps {         ...       }     }   } } 

Generally, the build stages execute on a build slave labeled "yona", but the input stage runs on the master.