metrics

Scraping a Docker Swarm service with Prometheus

Scraping a Docker swarm service from a Prometheus server that is outside the swarm is not as easy as it might look at a first glance. You have to fetch the metrics of all running service instances, but how to identify and access them? In this blog post I will demonstrate how this can be done quite easily by introducing an intermediate Prometheus instance within the Docker swarm and combining a couple of Prometheus features (mainly dns_sd_configs and cross service federation) to collect and fetch the required metrics data.