Prometheus Installation systemd

In this guide, we will demonstrate how to configure Prometheus to run as a background service managed by systemd. Running Prometheus directly from the terminal presents two primary challenges:

1. Prometheus runs in the foreground, meaning that closing the terminal also terminates the process.
2. It does not start automatically on boot, requiring manual intervention after each reboot.

Our objective is to set up a systemd unit for Prometheus so you can easily manage it using commands like "systemctl start prometheus" and ensure it launches on system startup.

Running Prometheus Manually

Initially, you might run Prometheus using:

$ ./prometheus

However, to integrate it with system services, you will want to use:

$ systemctl start prometheus

To enable this functionality, we will create a systemd unit file for Prometheus.

Creating a Dedicated Prometheus User

For security purposes, create a dedicated system user for running Prometheus. Since this account is not intended for interactive login, run the following command:

$ sudo useradd --no-create-home --shell /bin/false prometheus

Setting Up Directories for Configuration and Data

Create the necessary directories for Prometheus configuration and data storage. The convention is to store configuration files in /etc and persistent data in /var/lib.

$ sudo mkdir /etc/prometheus
$ sudo mkdir /var/lib/prometheus

After the directories are created, update their ownership to the Prometheus user and group.

Downloading and Installing Prometheus

Before proceeding, download the Prometheus binary from the official release repository. For example:

$ wget https://github.com/prometheus/prometheus/releases/download/v2.37.0/prometheus-2.37.0.linu

Once downloaded, extract the tarball. Then, transfer the Prometheus executable and the Promtool CLI utility to /usr/local/bin, which is the standard location for executables. Ensure these files are assigned to the Prometheus user for proper access control.

Configuring Prometheus Files

Next, copy the dashboard-related directories into the configuration directory. This includes the consoles and console libraries, which are essential for the Prometheus web interface:

$ sudo cp -r consoles /etc/prometheus
$ sudo cp -r console_libraries /etc/prometheus

Update the ownership of these copied directories:

$ sudo chown -R prometheus:prometheus /etc/prometheus/consoles
$ sudo chown -R prometheus:prometheus /etc/prometheus/console_libraries

Then, copy the main configuration file (prometheus.yaml) to /etc/prometheus and rename it as prometheus.yml:

$ sudo cp prometheus.yaml /etc/prometheus/prometheus.yml

Again, ensure that the configuration file has the proper ownership by the Prometheus user.

Running Prometheus with Custom Parameters

With the directories and configuration files in place, you can test the Prometheus binary with custom parameters. This command specifies the configuration file location, data storage path, and web console directories:

$ 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

Creating a systemd Unit File for Prometheus

To integrate Prometheus with systemd, create a new unit file:

$ sudo vi /etc/systemd/system/prometheus.service

Insert the following content into the file:

[Unit]
Description=Prometheus
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

Explanation:

• The [Unit] section ensures that Prometheus starts only after the network is online.
• In the [Service] section, Prometheus is assigned to run with the dedicated user and group, and the execution command is clearly defined.
• The [Install] section specifies that the service should be activated as part of the standard multi-user system startup.

Enabling and Starting the Prometheus Service

After saving the systemd unit file, reload systemd to register the new service:

$ sudo systemctl daemon-reload

Start the Prometheus service with the following command:

$ sudo systemctl start prometheus

Verify that Prometheus is running:

$ sudo systemctl status prometheus

Finally, enable the service to launch automatically upon system boot:

$ sudo systemctl enable prometheus