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Prometheus Docker

This guide outlines the steps to set up Prometheus and Node Exporter using Docker containers. It also addresses a common issue where the Prometheus container is unable to connect to the Node Exporter container, and how to resolve it by creating a Docker network.

Prerequisites​

  • Docker installed on the host machine.

Steps​

1. Create a Docker Network​

Creating a Docker network will ensure that the Prometheus and Node Exporter containers can communicate with each other.

docker network create prometheus-net

2. Run Node Exporter Container​

Run the Node Exporter container in the created network. This will expose Node Exporter on port 9100.

docker run --name node_exporter --network=prometheus-net -d -p 9100:9100 prom/node-exporter

3. Configure Prometheus​

Before running the Prometheus container, make sure to configure it correctly. Create a prometheus.yml file with the following content:

global:
  scrape_interval: 15s

scrape_configs:
  - job_name: 'prometheus'
    static_configs:
    - targets: ['localhost:9090']
  - job_name: 'node_exporter'
    static_configs:
    - targets: ['node_exporter:9100']

The targets under node_exporter should point to the name of the Node Exporter container and the port it's running on, which in this case is node_exporter:9100.

4. Run Prometheus Container​

Run the Prometheus container in the same network as Node Exporter. This will expose Prometheus on port 9090.

docker run --name prometheus --network=prometheus-net -d -p 9090:9090 -v /path/to/prometheus.yml:/etc/prometheus/prometheus.yml prom/prometheus

Replace /path/to/prometheus.yml with the actual path to your prometheus.yml configuration file.

5. Verify the Setup​

Open your web browser and navigate to http://localhost:9090. Click on Targets under the Status menu. You should see that the Node Exporter target is UP.

Troubleshooting​

If you encounter a connection refused error, double-check the following:

  • Both containers are running in the same Docker network.
  • The prometheus.yml configuration file has the correct targets for Node Exporter.
  • Ports 9090 and 9100 are open and not being used by other services.