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Configuring a Prometheus monitoring server with a Grafana dashboard

Published on 07 June 2018
  • compute
  • monitoring
  • Grafana
  • Prometheus
  • server
  • statistics

Prometheus - Overview

This tutorial explains how to use a Prometheus Monitoring server with a Grafana dashboard.

Prometheus is a flexible monitoring solution that is in development since 2012. The software stores all its data in a time series database and offers a multi-dimensional data-model and a powerful query language to generate reports of the monitored resources.


Preparing your environment

  1. Run the following command to create a user for Prometheus and Node Exporter. In this tutorial, we will create it without the login option.

    To achieve this, we use the parameter --no-create-home which skips the creation of a home directory and disable the shell with --shell /usr/sbin/nologin.

    sudo useradd --no-create-home --shell /usr/sbin/nologin prometheus
    sudo useradd --no-create-home --shell /bin/false node_exporter
  2. Create the folders required to store the binaries of Prometheus and its configuration files.

    sudo mkdir /etc/prometheus
    sudo mkdir /var/lib/prometheus
  3. Set the ownership of these directories to our prometheus user, to make sure that Prometheus can access to these folders.

    sudo chown prometheus:prometheus /etc/prometheus
    sudo chown prometheus:prometheus /var/lib/prometheus

Downloading and installing Node Exporter

As your Prometheus is only capable of collecting metrics, we want to extend its capabilities by adding Node Exporter, a tool that collects information about the system including CPU, disk, and memory usage and exposes them for scraping.

  1. Download the latest version of Node Exporter:

    wget https://github.com/prometheus/node_exporter/releases/download/v1.3.1/node_exporter-1.3.1.linux-amd64.tar.gz
  2. Unpack the downloaded archive. This will create a directory node_exporter-1.3.1.linux-amd64, containing the executable, a readme and license file:

    tar xvf node_exporter-1.3.1.linux-amd64.tar.gz
  3. Copy the binary file into the directory /usr/local/bin and set the ownership to the user you have created in step previously:

    sudo cp node_exporter-1.3.1.linux-amd64/node_exporter /usr/local/bin
    sudo chown node_exporter:node_exporter /usr/local/bin/node_exporter
  4. Remove the leftover files of Node Exporter, as they are not needed any longer:

    rm -rf node_exporter-1.3.1.linux-amd64.tar.gz node_exporter-1.3.1.linux-amd64
  5. To run Node Exporter automatically on each boot, a Systemd service file is required. Create the following file by opening it in Nano:

    sudo nano /etc/systemd/system/node_exporter.service
  6. Copy the following information in the service file, save it and exit nano:

    Description=Node Exporter



    Collectors are used to gather information about the system. By default, a set of collectors is activated. You can see the details about the set in the README file. If you want to use a specific set of collectors, you can define them in the ExecStart section of the service. Collectors are enabled by providing a --collector.<name> flag. Collectors that are enabled by default can be disabled by providing a --no-collector.<name> flag.

  7. Reload Systemd to use the newly defined service.

    sudo systemctl daemon-reload
  8. Run Node Exporter by typing the following command.

    sudo systemctl start node_exporter.service
  9. Verify that the software started successfully.

    sudo systemctl status node_exporter.service

    You will see an output like the following, showing you the status active (running) as well as the main PID of the application:

    â—Ź node_exporter.service - Node Exporter
    Loaded: loaded (/etc/systemd/system/node_exporter.service; disabled; vendo>
    Active: active (running) since Tue 2022-03-01 13:10:40 UTC; 11s ago
    Main PID: 21976 (node_exporter)
    Tasks: 4 (limit: 2335)
    Memory: 2.3M
    CGroup: /system.slice/node_exporter.service
    └─21976 /usr/local/bin/node_exporter
  10. If everything is working, enable Node Exporter to start upon boot.

    sudo systemctl enable node_exporter.service

Downloading and installing Prometheus

  1. Download and unpack Prometheus latest release of Prometheus. In this tutorial, we use version 2.34.0-rc.1.

    sudo apt-get update && apt-get upgrade
    wget https://github.com/prometheus/prometheus/releases/download/v2.34.0-rc.1/prometheus-2.34.0-rc.1.linux-amd64.tar.gz
    tar xfz prometheus-*.tar.gz
    cd prometheus-2.34.0-rc.1.linux-amd64/

    The following two binaries are in the directory:

    • prometheus - Prometheus’ main binary file
    • promtool

    The following two folders (which contain the web interface, configuration files examples and the license) are in the directory:

    • consoles
    • console_libraries
  2. Copy the binary files into the /usr/local/bin/directory:

    sudo cp ./prometheus /usr/local/bin/
    sudo cp ./promtool /usr/local/bin/
  3. Set the ownership of these files to the prometheus user previously created:

    sudo chown prometheus:prometheus /usr/local/bin/prometheus
    sudo chown prometheus:prometheus /usr/local/bin/promtool
  4. Copy the consoles and console_libraries directories to /etc/prometheus:

    sudo cp -r ./consoles /etc/prometheus
    sudo cp -r ./console_libraries /etc/prometheus
  5. Set the ownership of the two folders, as well as of all files that they contain, to our prometheus user:

    sudo chown -R prometheus:prometheus /etc/prometheus/consoles
    sudo chown -R prometheus:prometheus /etc/prometheus/console_libraries
  6. In our home folder, remove the source files that are not needed anymore:

    cd .. && rm -rf prometheus-\*

Configuring Prometheus

Prior to using Prometheus, it needs basic configuring. Thus, we need to create a configuration file named prometheus.yml


The configuration file of Prometheus is written in YAML which strictly forbids to use tabs. If your file is incorrectly formatted, Prometheus will not start. Be careful when you edit it.

  1. Open the file prometheus.yml in a text editor:

    sudo nano /etc/prometheus/prometheus.yml

    Prometheus’ configuration file is divided into three parts: global, rule_files, and scrape_configs.

    In the global part we can find the general configuration of Prometheus: scrape_interval defines how often Prometheus scrapes targets, evaluation_interval controls how often the software will evaluate rules. Rules are used to create new time series and for the generation of alerts.

    The rule_files block contains information of the location of any rules we want the Prometheus server to load.

    The last block of the configuration file is named scape_configs and contains the information which resources Prometheus monitors.

    Our file should look like this example:

    scrape_interval: 15s
    evaluation_interval: 15s

    # - "first.rules"
    # - "second.rules"

    - job_name: 'prometheus'
    scrape_interval: 5s
    - targets: ['localhost:9090']

    The global scrape_interval is set to 15 seconds which is enough for most use cases.

    We do not have any rule_files yet, so the lines are commented out and start with a #.

    In the scrape_configs part we have defined our first exporter. It is Prometheus that monitors itself. As we want to have more precise information about the state of our Prometheus server we reduced the scrape_interval to 5 seconds for this job. The parameters static_configsand targets determine where the exporters are running. In our case it is the same server, so we use localhost and the port 9090.

    As Prometheus scrapes only exporters that are defined in the scrape_configs part of the configuration file, we have to add Node Exporter to the file, as we did for Prometheus itself.

    We add the following part below the configuration for scrapping Prometheus:

    - job_name: 'node_exporter'
    scrape_interval: 5s
    - targets: ['localhost:9100']

    Overwrite the global scrape interval again and set it to 5 seconds. As we are scarping the data from the same server as Prometheus is running on, we can use localhost with the default port of Node Exporter: 9100.

    If you want to scrape data from a remote host, you have to replace localhost with the IP address of the remote server.


    For all information about the configuration of Prometheus, you may check the configuration documentation.

  2. Set the ownership of the file to our Prometheus user:

    sudo chown prometheus:prometheus /etc/prometheus/prometheus.yml

Our Prometheus server is ready to run for the first time.

Running Prometheus

  1. Start Prometheus directly from the command line with the following command, which executes the binary file as our Prometheus user:

    sudo -u prometheus /usr/local/bin/prometheus --config.file /etc/prometheus/prometheus.yml --storage.tsdb.path /var/lib/prometheus/ --web.console.templates=/etc/prometheus/consoles --web.console.libraries=/etc/prometheus/console_libraries

    The server starts displaying multiple status messages and the information that the server has started:

    level=info ts=2022-03-01T13:16:52.918475753Z caller=main.go:222 msg="Starting Prometheus" version="(version=2.3.1, branch=HEAD, revision=188ca45bd85ce843071e768d855722a9d9dabe03)"
    level=info ts=2022-03-01T13:16:52.918772613Z caller=main.go:223 build_context="(go=go1.10.3, user=root@82ef94f1b8f7, date=20180619-15:56:22)"
    level=info ts=2022-03-01T13:16:52.918893461Z caller=main.go:224 host_details="(Linux 5.4.0-96-generic #109-Ubuntu SMP Wed Jan 12 16:49:16 UTC 2022 x86_64 scw-elegant-greider (none))"
    level=info ts=2022-03-01T13:16:52.919003688Z caller=main.go:225 fd_limits="(soft=1024, hard=1048576)"
    level=info ts=2022-03-01T13:16:52.922302228Z caller=main.go:514 msg="Starting TSDB ..."
    level=info ts=2022-03-01T13:16:52.922560093Z caller=web.go:415 component=web msg="Start listening for connections" address=
    level=info ts=2022-03-01T13:16:52.949006143Z caller=main.go:524 msg="TSDB started"
    level=info ts=2022-03-01T13:16:52.949114617Z caller=main.go:603 msg="Loading configuration file" filename=prometheus.yml
    level=info ts=2022-03-01T13:16:52.951124437Z caller=main.go:500 msg="Server is ready to receive web requests."
  2. Open your browser and type http://IP.OF.YOUR.SERVER:9090 to access the Prometheus interface. If everything is working, we end the task by pressing on CTRL + C on our keyboard.


    If you get an error message when you start the server, double check your configuration file for possible YAML syntax errors. The error message will tell you what to check.

  3. The server is working now, but it cannot yet be launched automatically at boot. To achieve this, we have to create a new systemd configuration file that will tell your OS which services should it launch automatically during the boot process.

    sudo nano /etc/systemd/system/prometheus.service

    The service file tells systemd to run Prometheus as prometheus and specifies the path of the configuration files.

  4. Copy the following information in the file and save it, then exit the editor:

    Description=Prometheus Monitoring

    ExecStart=/usr/local/bin/prometheus \
    --config.file /etc/prometheus/prometheus.yml \
    --storage.tsdb.path /var/lib/prometheus/ \
    --web.console.templates=/etc/prometheus/consoles \
    ExecReload=/bin/kill -HUP $MAINPID

  5. To use the new service, reload systemd:

    sudo systemctl daemon-reload

    We enable the service so that it will be loaded automatically during boot:

    sudo systemctl enable prometheus.service
  6. Start Prometheus:

    sudo systemctl start prometheus.service

Your Prometheus server is ready to be used.

We have now installed Prometheus to monitor your instance.

Prometheus Web Interface

Prometheus provides a basic web server running on http://your.server.ip:9090 that provide access to the data collected by the software.

We can verify the status of our Prometheus server from the interface:

You can perform queries with the collected data.

The interface we set up is lightweight. The Prometheus team, therefore, recommends using a tool like Grafana if you want to do more than testing and debugging the installation.

Installing Grafana

  1. Install Grafana on our Instance which queries our Prometheus server.
    sudo apt-get install -y adduser libfontconfig1
    wget https://dl.grafana.com/oss/release/grafana_8.4.3_amd64.deb
    sudo dpkg -i grafana_8.4.3_amd64.deb
  2. Enable the automatic start of Grafana by systemd:
    sudo systemctl daemon-reload && sudo systemctl enable grafana-server.service && sudo systemctl start grafana-server.service

Grafana is running now, and we can connect to it at http://your.server.ip:3000. The default user and password is admin / admin.

Now you have to create a Prometheus data source:

  • Click the cogwheel icon on the sidebar
  • Click Data Sources
  • Choose Add data source
  • Select Prometheus as the data source
  • Set the Prometheus server URL (in our case: http://localhost:9090/)
  • Click Save & test to test the connection and to save the new data source

Your settings should look like this:

You are now ready to create your first dashboard from the information collected by Prometheus. You can also import some dashboards from a collection of shared dashboards

Below is an example of a dashboard that uses the CPU usage of our node and presents it in Grafana: