Deploying Docker Flow Monitor

Deploying Docker Flow Monitor is easy (as almost all Docker services are). We'll start by creating a network called monitor. We could let Docker stack create it for us, but it is useful to have it defined externally so that we can easily attach it to services from other stacks:

docker network create -d overlay monitor  

The stack is as follows:

version: "3" 
services: 
  monitor: 
    image: vfarcic/docker-flow-monitor:${TAG:-latest} 
    environment: 
      - GLOBAL_SCRAPE_INTERVAL=10s 
    networks: 
      - monitor 
    ports: 
      - 9090:9090 
networks: 
    monitor: 
       external: true 

The environment variable GLOBAL_SCRAPE_INTERVAL shows the first improvement over the "original" Prometheus service. It allows us to define entries of its configuration as environment variables. That, in itself, is not a significant improvement but is a good start. More powerful additions will be explored later on.

Please visit environment variables section of the documentation for more information about configuration options at (http://monitor.dockerflow.com/config/#environment-variables).

Now we're ready to deploy the stack:

docker stack rm monitor
    
docker stack deploy \
    -c stacks/docker-flow-monitor.yml \
    monitor

Please wait a few moments until Swarm pulls the image and starts the service. You can monitor the status by executing docker stack ps monitor command.

Once the service is running, we can confirm that the environment variable indeed generated the configuration:

open "http://$(docker-machine ip swarm-1):9090/config"

Figure 3-6: Prometheus configuration defined through environment variables

Please note that you do not have to use Docker Flow Monitor to accomplish the same Prometheus configuration. We are using it mostly as a fast and dynamic way to configure it. You can choose to do the same by changing its configuration manually.

We are going to expose services url in pretty format, therefore we must get rid of port number (9090) in preceding url.