Setting build args for dockerfile agent using a Jenkins declarative pipeline

Question

I\'m using the declarative pipeline syntax to do some CI work inside a docker container.

I\'ve noticed that the Docker plugin for Jenkins runs a container using the

Answer 1

I verified that trying to assign user_id and group_id without a node didn't work, as you found, but this worked for me to assign these values and later access them:

def user_id
def group_id
node {
  user_id = sh(returnStdout: true, script: 'id -u').trim()
  group_id = sh(returnStdout: true, script: 'id -g').trim()
}

pipeline {
  agent { label 'docker' }
  stages {
    stage('commit_stage') {
      steps {
        echo 'user_id'
        echo user_id
        echo 'group_id'
        echo group_id
      }
    }
  }
}

Hopefully these will also work in your additionalBuildArgs statement.

In a comment, you pointed out what is most likely a critical flaw with the approach that figures out the user_id and group_id outside the declarative pipeline before using it to configure the dockerfile: the slave on which it discovers the user_id will not necessarily match up with the slave that it uses to kick off the docker-based build. i don't there is any way around this while also keeping the declarative Jenkinsfile constraint.

You can guarantee one slave for all stages by using a global agent declaration: Jenkins declarative pipeline: What workspace is associated with a stage when the agent is set only for the pipeline?

But multiple node references with the same label don't guarantee the same workspace: Jenkins declarative pipeline: What workspace is associated with a stage when the agent is set only for the pipeline?