In the last few years energy efficiency of large scale infrastructures gained a lot of attention, as power consumption became one of the most impacting factors of the operative costs of a data-center and of its Total Cost of Ownership. Power consumption can be observed at different layers of the data-center: from the overall power grid, moving to each rack and arriving to each machine and system. Given the rise of application containers in the cloud computing scenario, it becomes more and more important to measure power consumption also at the application level, where power-aware schedulers and orchestrators can optimize the execution of the workloads not only from a performance perspective, but also considering performance/power trade-offs. DEEP-mon is a novel monitoring tool able to measure power consumption and attribute it for each thread and application container running in the system, without any previous knowledge regarding the characteristics of the application and without any kind of workload instrumentation. DEEP-mon is able to aggregate data for threads, application containers and hosts with a negligible impact on the monitored system and on the running workloads. Information obtained with DEEP-mon open the way for a wide set of applications exploiting the capabilities offered by the monitoring tool, from power (and hence cost) metering of new software components deployed in the data center, to fine grained power capping and power-aware scheduling and co-location.