How to get SimpleBuildWrapper decorateLauncher behavior in Pipeline Wrapper

[Caleb Lloyd]

I am trying to implement a Pipeline Wrapper that runs commands in an LXD Container.

I see that SimpleBuildWrapper has a decorateLauncher method that seems like it would be perfect.  But the "HelloWorldWrapper decorateLauncher" message is never logged, and it seems that decorateLauncher is not getting called in my Pipeline stage.

Here is the pipeline code:

package org.boxboat.plugins.lxd;

import hudson.EnvVars;

import hudson.Extension;

import hudson.FilePath;

import hudson.Launcher;

import hudson.model.*;

import hudson.tasks.BuildWrapperDescriptor;

import jenkins.tasks.SimpleBuildWrapper;

import org.kohsuke.stapler.DataBoundConstructor;

import java.io.IOException;

import java.util.logging.Logger;

public class HelloWorldWrapper extends SimpleBuildWrapper {

    private final static Logger Log = Logger.getLogger(HelloWorldWrapper.class.getName());

    @DataBoundConstructor

    public HelloWorldWrapper() {

        super();

        Log.info("HelloWorldWrapper construct");

    }

    @Override

    public void setUp(Context context, Run<?, ?> run, FilePath filePath, Launcher launcher, TaskListener taskListener, EnvVars envVars) throws IOException, InterruptedException {

        Log.info("HelloWorldWrapper setUp");

    }

    @Override

    public Launcher decorateLauncher(final AbstractBuild build, final Launcher launcher, final BuildListener listener) throws IOException, InterruptedException, Run.RunnerAbortedException {

        Log.info("HelloWorldWrapper decorateLauncher");

        return new LxdDecoratedLauncher(launcher);

    }

    @Extension

    public static class DescriptorImpl extends BuildWrapperDescriptor {

        @Override public boolean isApplicable(AbstractProject<?,?> item) {

            return true;

        }

    }

}

Here is my Jenkinsfile:

pipeline {

    agent any

    stages {

        stage('Test') {

            steps {

                wrap([$class: 'org.boxboat.plugins.lxd.HelloWorldWrapper']) {

                    sh '''

                    ls /tmp

                    cat /tmp/jenkins'''

                }

            }

        }

        stage('Publish') {

            steps {

                wrap([$class: 'org.boxboat.plugins.lxd.HelloWorldWrapper']) {

                    sh '''

                    ls /tmp

                    cat /tmp/jenkins'''

                }

            }

        }

    } 

}

How do I achieve launcher decoration in pipeline mode?  It seems that this would be very useful for LXC, chroot, and the likes.

Thanks

[Jesse Glick]

As noted in https://github.com/jenkinsci/jenkins/blob/d13b1361e1650494528a7b46f82fe25d7fb5e3c3/core/src/main/java/jenkins/tasks/SimpleBuildWrapper.java#L203-L207
this is not currently supported by `SimpleBuildWrapper`, as is noted
in the Javadoc for the method you are overriding.

You would need to create a custom `Step` with a body argument, and use
`BodyInvoker.mergeLauncherDecorators`, as for example the
`docker-workflow` plugin does to run nested `sh` steps inside a
container.