Swarm tasks exporter

This little Prometheus exporter provides two metrics to better monitor Swarm tasks and their state.

Summary

• How it works
• Metrics
• Install
• Configure

How it works?

In its current state, the exporter does:

• Watch swarm events about service create/update/remove, to update the number of desired replicas for replicated services.
• Watch swarm events about node create/remove, to update the number of desired replicas for global services.
• Regularly poll task list to update the gauge of service tasks segmented by state.

Metrics

• swarm_service_desired_replicas: Gauge of how many replicas is desired, for every Swarm service (labels: stack, service, service_mode).
• swarm_service_replicas_state: Gauge of tasks state (labels: stack, service, service_mode, state).

Install

This exporter is available on Docker Hub: akerouanton/swarm-tasks-exporter:

docker run -v /var/run/docker.sock:/var/run/docker.sock:ro akerouanton/swarm-tasks-exporter

Or, with docker-compose (or Swarm):

services:
  tasks_exporter:
    image: akerouanton/swarm-tasks-exporter:0.1.0
    command: -log-level error
    volumes:
      - '/var/run/docker.sock:/var/run/docker.sock:ro'
    networks:
      - monit_prometheus
    deploy:
      replicas: 1
      restart_policy:
        condition: on-failure
      placement:
        constraints:
          - node.role == manager     

As you can see, when you want to deploy it to a Swarm cluster, it has to be scheduled on a manager node, or it won't be able to access cluster events.

Configure

You can use following flags to configure the exporter:

• -listen-addr <ip:port>: IP address and port to listen to (default 0.0.0.0:8888).
• -poll-delay: Delay in seconds between two polls (default 10s).
• -label: Add custom labels to metrics
• -log-format: How log should be formatted. Either json or text (default text).
• -log-level: What's the minimum level of logs. Either debug, info, warn, error, fatal or panic (default info).

Moreover, this exporter supports the same env vars as the docker client:

• DOCKER_HOST to set the url to the docker server
• DOCKER_CERT_PATH to load the TLS certificates from.
• DOCKER_TLS_VERIFY to enable or disable TLS verification, off by default.