docker-compose-prometheus

A set of Docker Compose configs to run a local Prometheus test environment

Table of contents

• Introduction
• Getting started
  • Existing services
• Architecture and layout
  • Networking
• Extending

Introduction

This repository contains the configuration required to create local Prometheus and Grafana containers and link them together so you can experiment with metric collection and graphing.

Although it makes it possible to bootstrap a very simple, 2 container infrastructure the most useful additions are the configs in the other directories. Each of these will add a service and exporter that link in to the base prometheus and allow you to experiment and learn how to monitor and graph other services. A good place to start is with the the Prometheus and Redis combination documented below.

Getting started

The only things you need to run these examples are docker-compose and a copy of this repo. Everything else happens inside the docker containers.

A note about the hideous command lines. In order to make this a modular experiment I've extracted the separate sections of config in to different directories. While this allows you to spin up a test site with any combination of services and exporters it does mean you'll need to add a -f $foo/docker-compose.yaml argument for each service you want to include in the test. I avoid the pain by setting an alias:

alias dc='docker-compose -f prometheus-server/docker-compose.yaml -f redis-server/docker-compose.yaml'

And then use commands like dc up -d and dc logs. In the README examples I'll use the full commands for clarity but you won't have to.

Creating Prometheus

The first part of the infrastructure you should build, and the one depended on by all the example service configurations in other directories, is prometheus-server. This will create both a prometheus and grafana container. At the moment we'll have to manually link these together.

From the root of this repo run the command to create the docker containers.

docker-compose -f prometheus-server/docker-compose.yaml up -d

On the first run this might take a little while as it fetches all the containers. Once it returns you can confirm the containers are running:

docker-compose -f prometheus-server/docker-compose.yaml ps

> docker-compose -f prometheus-server/docker-compose.yaml ps
            Name                           Command             State   Ports
-----------------------------------------------------------------------------------------
prometheusserver_grafana_1      /run.sh                        Up  0.0.0.0:3000->3000/tcp
prometheusserver_prometheus_1   /bin/prometheus --config.f ... Up  0.0.0.0:9090->9090/tcp

and view their output:

docker-compose -f prometheus-server/docker-compose.yaml logs

When you're finished you can remove the containers, but don't do that yet.

docker-compose -f prometheus-server/docker-compose.yaml down

Once the containers have been created you can view the Prometheus dashboard and the Grafana Dashboard (login with admin / secret).

Now Grafana 5 has been released we can move to configuring the Prometheus data source with a datasource.yaml file and remove the manual steps. You should still click through to the import dashboard page screen and import each of those available. You can then view the Prometheus graphs.

Congratulations! You now have a prometheus and grafana test instance and you can experiment with making your own scrape backed graphs. You'll soon want to expand into data from other services, and an ideal place to start is with Redis.

Existing Services

This repo currently contains example configurations for the following services and their respective exporters:

• Memcached
• Node exporter - just an exporter running against your local host
• PostgreSQL
• Prometheus and Grafana
• Redis Server

Networking

All the containers are created inside a single docker network and reference each other by the magic of their service names. They can also be reached from the host on 127.0.0.1. This allows easier access to the prometheus and grafana dashboards and means you can easily add sample data to the graphs by running command such as redis-cli in a loop or pointing a load tester at them.

Architecture and layout

One of the key goals in this experiment is to keep it as modular as possible and allow you to create container networks of whichever combination you need. Does your application use PostgreSQL and redis? Add a new docker- compose.yaml for your application itself and just include redis-server/docker- compose.yaml and postgresql-server/docker-compose.yaml on the command line to create those backing services and collect metrics on them all.

To implement this we have a subdirectory for each different thing we want to collect metrics for. This contains the prometheus target configuration file, mostly in ${subdirectory_name}.json and a docker- compose.yaml file that defines how to run the service inside a container. Critically, the compose file contains an additional prometheus service definition.

  prometheus:
    volumes:
      - ${PWD}/redis-server/redis.json:/etc/prometheus/targets/redis.json

Docker compose has a wonderful feature that ensures additional values for a service, even one defined in a separate docker-compose file, are merged to create a configuration that contains all encountered keys. In the case of this repo it means we can define the basic prometheus checks in the base docker-compose.yaml file and add the additional checks as we include the services they target.

Extending

Adding a new data source or your own application should be a simple process.

• create a new subdirectory
• add a docker-compose.yaml file that can run your container
• ensure the prometheus: volume line points to your own service
• add the prometheus target config in the service specific json file
• run docker-compose up with all the services you want specified using multiple -f $foo/docker-compose.yaml arguments
• add a README detailing your work

Debugging

To extract the complete base prometheus config file so you can check its contents after it is concatenated.

docker cp prometheus-server_config-concat_1:/fragments/complete/prometheus.yml /tmp/prometheus.yml

Author

Dean Wilson