Jenkins Declarative Pipeline: Run a stage without holding up an agent

If you have a Jenkins declarative pipeline , you’re generally bound to have more than one stage with steps within each of them. The usual way of declaring a node/agent/slave is by declaring an agent directive encompassing the stages{} directive, like so:

pipeline {
    agent { label 'mynode' }
    stages { 
        stage('Example') {
            steps {
                echo 'Hello World'
            }
        }
    }
}

However, occasionally you may wish to run a stage or two that doesn’t require an agent. A simple example would be a timeout or a sleep stage that is waiting for a previous stage to finish. If your timeout lasts more than a few minutes, you’d want to release the agent so another build may use it. Holding up an agent is a crime in Jenkins world.

(Although this is shown in the document link I shared above, it isn’t tagged for this usecase as such.)

Here’s a simple way to go about doing that:

pipeline {
    agent none

    stages {

        stage('Stage Do Something') {
            agent { label 'mynode' }
            steps {
                    echo "Something"
            }
        }

        stage('Stage Sleep') {
            agent none
            steps {
                sleep time: 3, unit: 'HOURS'
            }
        }


        stage('Stage Do More Of Something') {
            agent { label 'mynode' }
            steps {
                    echo "More Of Something"
                }
            }
    }
}

‘Stage Sleep’ here is declared with agent none which simply retires the agent until it is called again in the next stage.

Hope that helps someone looking for a quick answer.