Configuring Prometheus
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Prior to using Prometheus, it needs basic configuring. Thus, we need to create a configuration file named prometheus.yml
Open the file prometheus.yml in a text editor:
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:
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 scraping Prometheus:
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.
Set the ownership of the file to our Prometheus user:
Our Prometheus server is ready to run for the first time.
Start Prometheus directly from the command line with the following command, which executes the binary file as our Prometheus user:
The server starts displaying multiple status messages and the information that the server has started:
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.
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.
The service file tells systemd to run Prometheus as prometheus and specifies the path of the configuration files.
Copy the following information in the file and save it, then exit the editor:
To use the new service, reload systemd:
We enable the service so that it will be loaded automatically during boot:
Start Prometheus:
Your Prometheus server is ready to be used.
We have now installed Prometheus to monitor your instance. Prometheus provides a basic web server running on http://your.server.ip:9000 that provide access to the data collected by the software.
Tip: For all information about the configuration of Prometheus, you may check the .