Docker Swarm Prometheus Exporter

Basic Prometheus exporter for a Docker Swarm.

Exposes a /metrics HTTP endpoint for Prometheus to scrape which has basic info on what services are running and how many tasks are in what state for each service.

By default the endpoint is on port 9675 in accordance with the Prometheus Default Port Allocations.

Environment Variables

Debug Logging

Set DEBUG=1 to enable a more verbose level of logging to stdout.

Docker Host

Set DOCKER_HOST to a different socket address to override the OS default. E.g. DOCKER_HOST=unix:///var/run/docker.sock to use another endpoint to talk to a remote docker host.

Running

There are two ways that you can run this:

Standalone

You can run the binary on the docker host. It will need permission to access the docker daemon.

Inside Docker

You can run the exporter as a container inside Docker. For this to work you have to bind-mount /var/run/docker.sock from the host machine into the container. An example docker-compose file is provided.

You can pull the most recent image with docker pull ghcr.io/tardoe/docker_swarm_exporter:latest

Metrics Exposed

swarm_service_tasks

Number of tasks for each service in each state. At the moment we don't include zero values (which is against Prometheus guidelines but reduces the amount of data by an order of magnitude).

swarm_service_desired_replicas

Number of tasks which each service is supposed to be running.

swarm_service_info

Version info about the image used to run a service. The useful stuff is in the labels, the value is always 1 (see https://www.robustperception.io/exposing-the-software-version-to-prometheus).

swarm_service_change_time

The most recent time when any of the tasks for a service changed state, as a unix timestamp.

container_health_status

The container health-check status exposed as the container_health_status label for each container.

container_status

The container running status exposed as the container_status label for each container.

Example

This is the (relevant) output from an example stack called test with two services - redis and the exporter itself.

# HELP container_health_status Container Health Status
# TYPE container_health_status gauge
container_health_status{container_health_status="healthy",container_name="/test_prometheus_exporter.e8kpwn58x6l9ibrqdf5zc1z7x.vkv5eq76sdkkwsk81f7df5149"} 1

# HELP container_status Container status
# TYPE container_status gauge
container_status{container_name="/test_prometheus_exporter.e8kpwn58x6l9ibrqdf5zc1z7x.vkv5eq76sdkkwsk81f7df5149",container_status="running"} 1

# HELP swarm_service_change_time Time when a task state last changed
# TYPE swarm_service_change_time gauge
swarm_service_change_time{service_name="test_prometheus_exporter"} 1.581768126e+09
swarm_service_change_time{service_name="test_redis"} 1.581768125e+09

# HELP swarm_service_desired_replicas Number of replicas requested for this service
# TYPE swarm_service_desired_replicas gauge
swarm_service_desired_replicas{service_name="test_prometheus_exporter"} 1
swarm_service_desired_replicas{service_name="test_redis"} 1

# HELP swarm_service_info Information about each service
# TYPE swarm_service_info gauge
swarm_service_info{image="docker_swarm_exporter:latest",service_name="test_prometheus_exporter"} 1
swarm_service_info{image="redis:latest@sha256:7b84b346c01e5a8d204a5bb30d4521bcc3a8535bbf90c660b8595fad248eae82",service_name="test_redis"} 1

# HELP swarm_service_tasks Number of docker tasks
# TYPE swarm_service_tasks gauge
swarm_service_tasks{service_name="test_prometheus_exporter",state="running"} 1
swarm_service_tasks{service_name="test_redis",state="preparing"} 1
swarm_service_tasks{service_name="test_redis",state="running"} 0