Grafana Cloud - Docker & Alloy - PoC

This is a simple proof-of-concept that illustrates the basics of collecting Docker metrics and writing them to Grafana Cloud using:

1. Grafana Alloy
2. cAdvisor
3. node-exporter

Prerequisites

As we'll be making use of Grafana Cloud's Free Tier, you need to have your account and stack ready. If you didn't already do so, you can sign-up here.

Next, head over to your stack in Grafana Cloud and select "Send Metrics" under Prometheus. If no API token has been created yet, press "Generate now". When done, copy config.alloy.example to config.alloy and merge the configuration snippet in there.

In order to collect metrics from Docker, you need to specify a metrics-address in the daemon.json configuration file. This daemon expects the file to be located at one of the following locations by default. If the file doesn't exist, create it.

• Linux: /etc/docker/daemon.json
• Windows Server: C:\ProgramData\docker\config\daemon.json
• Docker Desktop: Open the Docker Desktop settings and select Docker Engine to edit the file.

Add the following configuration to listen on the docker0 interface:

{
  "metrics-addr": "172.17.0.1:9323"
}

You can check which address is in use on your docker0 interface using command (172.17.0.1 in our case):

ip addr show docker0 | grep -Po 'inet \K[\d.]+'`

Running

When all prerequisites have been met, this PoC can be launched using "Docker Compose":

docker compose up -d

Within a minute or so you should see your first metrics appear in Grafana Cloud. To see what's happening, tail the logs using:

docker compose logs -f