Install and Configure Prometheus on CentOS 8

Welcome to our guide on how to install and configure Prometheus on CentOS 8. Prometheus is an  open-source time series collection and processing monitoring system with a dimensional data model, flexible query language, efficient time series database and modern alerting approach.

Installing Prometheus on CentOS 8

Want to Install Prometheus on Ubuntu 18/Debian 9. Check the links below;

Install Prometheus on Ubuntu 18.04

Install and Configure Prometheus on Debian 9

Create Prometheus System User and Group

Run the command below to create prometheus system user and group.

useradd -M -r -s /bin/false prometheus

To verify this, you can try to print prometheus user and group information using the id command;

getent passwd prometheus
prometheus:x:986:985::/home/prometheus:/bin/false

Create Prometheus Configuration Directories

Since we are installing Prometheus from source, you need to create the respective configuration directories.

mkdir /etc/prometheus
mkdir /var/lib/prometheus

Download Prometheus Tarball

In order to install the latest version of Prometheus, navigate to the Download’s Page and grab Prometheus binary for your platform. You can simply run the command below to download version 2.14.0 (latest version as of this writing) for Linux systems.

wget https://github.com/prometheus/prometheus/releases/download/v2.14.0/prometheus-2.14.0.linux-amd64.tar.gz -P /tmp

Extract Prometheus Tarball

Once the download is done, extract the archive.

cd /tmp

tar -xzf prometheus-2.14.0.linux-amd64.tar.gz

ls prometheus-2.14.0.linux-amd64

console_libraries  consoles  LICENSE  NOTICE  prometheus  prometheus.yml  promtool  tsdb

Copy the two Prometheus binary files, prometheusand promtool, under the extracted Prometheus archive directory to the /usr/local/bin directory.

cp prometheus-2.14.0.linux-amd64/{prometheus,promtool} /usr/local/bin/

Copy the consoles/ and console_libraries/ directories to /etc/prometheus directory created above.

cp -r prometheus-2.14.0.linux-amd64/{consoles,console_libraries} /etc/prometheus/

Configure Prometheus on CentOS 8

The sample Prometheus configuration file, prometheus.yml, is located under the extracted archive directory.

Since we are doing a basic setup, we will copy the configuration file and modify it as follows such that it can scrape the local system only (Prometheus server).

cp prometheus-2.14.0.linux-amd64/prometheus.yml /etc/prometheus/

Next, open the configuration file for modification and adjust it such that it looks like;

vim /etc/prometheus/prometheus.yml

# my global config
global:
  scrape_interval:     15s # Set the scrape interval to every 15 seconds. Default is every 1 minute.
  evaluation_interval: 15s # Evaluate rules every 15 seconds. The default is every 1 minute.
  # scrape_timeout is set to the global default (10s).

# A scrape configuration containing exactly one endpoint to scrape:
# Here it's Prometheus itself.
scrape_configs:
  # The job name is added as a label `job=<job_name>` to any timeseries scraped from this config.
  - job_name: 'prometheus'

    # metrics_path defaults to '/metrics'
    # scheme defaults to 'http'.

    static_configs:
    - targets: ['localhost:9090']

Allow Prometheus through firewall.

firewall-cmd --add-port=9090/tcp --permanent

Reload firewalld

firewall-cmd --reload

Set Proper Ownership on Configuration Files and Directories

Run the command below to set the ownership (owner and group) of Prometheus configuration files and directories to prometheus.

chown -R prometheus:prometheus /etc/prometheus

chown -R prometheus:prometheus /var/lib/prometheus

chown prometheus.prometheus /usr/local/bin/{prometheus,promtool}

Starting Prometheus

To start Prometheus with our basic configuration file,run:

prometheus --config.file=/etc/prometheus/prometheus.yml

...
level=info ts=2019-11-13T17:33:55.867Z caller=main.go:743 msg="Loading configuration file" filename=/etc/prometheus/prometheus.yml
level=info ts=2019-11-13T17:33:56.353Z caller=main.go:771 msg="Completed loading of configuration file" filename=/etc/prometheus/prometheus.yml
level=info ts=2019-11-13T17:33:56.353Z caller=main.go:626 msg="Server is ready to receive web requests."

You should able to access the Prometheus status page at http://localhost:9090 if you are accessing the server locally or http://<server-IP>:9090 if you are accessing remotely.

Create Prometheus Systemd Service file

To be able to run Prometheus as a service, you need to create a systemd service file, /etc/systemd/system/prometheus.service, configured as follows.

Note that this assumes Prometheus server is listening on default port 9090.

vim /etc/systemd/system/prometheus.service

[Unit]
Description=Prometheus Time Series Collection and Processing Server
Wants=network-online.target
After=network-online.target

[Service]
User=prometheus
Group=prometheus
Type=simple
ExecStart=/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

[Install]
WantedBy=multi-user.target

Reload systemd daemon configuration.

systemctl daemon-reload

Start and Enable Prometheus service to run at boot time.

systemctl enable --now prometheus

Check the status

systemctl status prometheus

● prometheus.service - Prometheus Time Series Collection and Processing Server
   Loaded: loaded (/etc/systemd/system/prometheus.service; enabled; vendor preset: disabled)
   Active: active (running) since Wed 2019-11-13 20:47:02 EAT; 24s ago
 Main PID: 2931 (prometheus)
    Tasks: 7 (limit: 5072)
   Memory: 23.2M
   CGroup: /system.slice/prometheus.service
           └─2931 /usr/local/bin/prometheus --config.file /etc/prometheus/prometheus.yml --storage.tsdb.path /var/lib/prometheus/ --web.console.libraries=/etc/prometheus/console_libraries

Check that prometheus is listening on TCP port 9090.

lsof -i :9090

COMMAND    PID       USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
prometheu 2931 prometheus    3u  IPv6  39243      0t0  TCP localhost:websm->localhost:45648 (ESTABLISHED)
prometheu 2931 prometheus    7u  IPv6  39251      0t0  TCP localhost:47936->localhost:websm (ESTABLISHED)
prometheu 2931 prometheus    8u  IPv6  39239      0t0  TCP *:websm (LISTEN)
prometheu 2931 prometheus    9u  IPv6  39252      0t0  TCP localhost:websm->localhost:47936 (ESTABLISHED)
prometheu 2931 prometheus   10u  IPv4  39242      0t0  TCP localhost:45648->localhost:websm (ESTABLISHED)

Great, Prometheus is now running as a service.

You can now check the status of the connected targets. Click Status dropdown and then Targets. At the moment, we only have Prometheus scraping the localhost on which it is running.

You can also check local system metrics for example to check memory statistics for example “go_memstats_frees_total“.

For graphical overview, click Graph.

Feel free to explore more about Prometheus here.

In our next guides, we will be covering how to monitor other targets using Prometheus. Enjoy.

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