Jenkinsfile definition for a python service that will automatically generate a requirements.txt file from the pyproject.toml file using poetry, in a container, before building the service's Dockerfile and uploading it.

Jenkinsfile

pipeline {
    agent none
    stages {
        stage("Clone & Prepare")
        {
            agent {
                docker { 
                  image 'python:latest'
                  registryUrl "https://index.docker.io/v1/"
                }
            }
            stages {
                stage("Clone repository") {
                    steps {
                        checkout scm
                    }
              }
                stage("Install Poetry") {
                    steps {
                        sh "pip install poetry"
                        sh "poetry self add poetry-plugin-export"
                        sh "poetry install --only main"
                    }
                }
                stage("Generate Requirements")
                {
                    steps {
                        sh "poetry export -f requirements.txt --output requirements.txt --only main"
                    }
                }
            }
            post
            {
                cleanup{
                    sh "pip uninstall poetry --yes"
                }
            }
        }

        stage("Build & Push Docker Image")
        {
            environment {
                APPLICATION_NAME = env.GIT_URL.replaceFirst(/^.*\/([^\/]+?).git$/, '$1')
            }
            agent any
            steps {
                script {
                    def app
                    app = docker.build("${APPLICATION_NAME}")
                    docker.withRegistry("${env.MYDOCKER_REGISTRY_URL}") {
                        app.push("0.0.${env.BUILD_ID}")
                        app.push("latest")
                    }
                }
            }
        }
    }
}

re-defining the docker url was necessary because without it Jenkins picked up the url from my local repository in the "Build & Push Docker Image" stage and using that for some reason
another important piece of information is that the repository should not have a checked-in requirements.txt file otherwise that second main stage which will re-pull the git repository will overwrite the generated requirements file with the source control requirements file, and if you forgot to re-generate it for source control then the un-updated version will end up in the docker image