This document summarizes the challenges faced by SocGen, a large French bank, in implementing machine learning at scale using Spark and MLflow. Some key challenges included: 1) Keeping data and models local for regulatory reasons while performing training and prediction, 2) Ensuring reliability when moving models between prototyping and production phases, 3) Managing different Python package dependencies, 4) Tracking and managing many models, and 5) Ensuring high availability of the tracking server. The presentation provided a concrete example of using Spark, MLflow, and Kafka to periodically retrain a model for scoring news articles and handling user feedback in a scalable and reliable way.