Mining data from your servers is crucial to understanding what's going on with your hardware and network. Jack Wallen shows you how to install a powerful monitoring system for this purpose.

Image: Jack Wallen

Prometheus is an incredibly powerful, open source system that collects metrics from your server's services and stores them in a searchable database. With a highly dimensional data model, where you can run queries to slice and dice a collected series of data to generate ad-hoc graphs, tables, and alerts, Prometheus allows you to integrate any number of third-party data exporters (such as for Docker, HAProxy, StatsD, JMX metrics, and more).

Out of the box, Prometheus only exports data about itself, which isn't terribly useful. To expand Prometheus, it is possible to add exporters to the Prometheus system. You'll find exporters such as:

node_exporter--produces hardware metrics (CPU, memory, disk usage, I/O, network statistics, etc.)

blackbox_exporter--generates metrics from HTTP and HTTPS protocols.

mysqld_exporter--gathers MySQL server metrics.

nginx-vts-exporter--gathers metrics for the NGINX web server.

I want to walk you through the process of installing Prometheus and node_exporter on Ubuntu Server 16.04.

Preparing for the installation

The first thing we must do is create the necessary users and directories for Prometheus. You will also need to have NGINX installed on the system. To install NGINX, issue the following commands from a terminal window:

sudo apt install nginx sudo systemctl start nginx sudo systemctl enable nginx

With NGINX installed, you can then begin the process of creating special users (they will be service-only users, not users that can log into the system). Back at your terminal window, issue the following commands:

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

Next we create the necessary directories that will be used to store files and data. Issue the following commands to create the directories and give them the correct permissions:

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

Download and install

We're ready to download and install Prometheus. Back at your terminal window, issue the following commands to download the necessary file:

cd curl -LO https://github.com/prometheus/prometheus/releases/download/v2.0.0/prometheus-2.0.0.linux-amd64.tar.gz

Unpack that downloaded file with the command:

tar xvf prometheus-2.0.0.linux-amd64.tar.gz

Next we need to copy the binary files into the correct locations and fix the permissions. This is done with the following four commands:

sudo cp prometheus-2.0.0.linux-amd64/prometheus /usr/local/bin/ sudo cp prometheus-2.0.0.linux-amd64/promtool /usr/local/bin/ sudo chown prometheus:prometheus /usr/local/bin/prometheus sudo chown prometheus:prometheus /usr/local/bin/promtool

With the binaries in place, there are libraries that need to next be copied and ownership fixed. Issue the following four commands:

sudo cp -r prometheus-2.0.0.linux-amd64/consoles /etc/prometheus sudo cp -r prometheus-2.0.0.linux-amd64/console_libraries /etc/prometheus sudo chown -R prometheus:prometheus /etc/prometheus/consoles sudo chown -R prometheus:prometheus /etc/prometheus/console_libraries

Configure and run Prometheus

A new configuration file must be created. Issue the command sudo nano /etc/prometheus/prometheus.yml. In that file add the following content:

global: scrape_interval: 15s scrape_configs: - job_name: 'prometheus' scrape_interval: 5s static_configs: - targets: ['localhost:9090']

The above configuration will set up a scrape every 15 seconds. Save and close that file (we'll be coming back to it in a moment).

We now need to create a file for the systemd service. Issue the command sudo nano /etc/systemd/system/prometheus.service. In that new file, add the following content:

[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

Save and close that file. Reload systemd with the command sudo systemctl daemon-reload. With systemd reloaded, you can now start and enable Prometheus with the following two commands:

sudo systemctl start prometheus sudo systemctl enable prometheus

If you point your browser to http://SERVER_IP:9090 (where SERVER_IP is the actual IP address of your server), you should now see the Prometheus site (Figure A).

Figure A

At this point, Prometheus is only reporting on itself. Let's fix that.

Adding an exporter

As I mentioned, we're going to add node_exporter. The first thing you must down download the requisite file with the following two commands:

cd curl -LO https://github.com/prometheus/node_exporter/releases/download/v0.15.1/node_exporter-0.15.1.linux-amd64.tar.gz

Extract the file with the following command:

tar xvf node_exporter-0.15.1.linux-amd64.tar.gz

Copy the binary file into the necessary directory, and give it the proper permissions with the following commands:

sudo cp node_exporter-0.15.1.linux-amd64/node_exporter /usr/local/bin sudo chown node_exporter:node_exporter /usr/local/bin/node_exporter

Next we need to create a systemd file for node_exporter. Issue the command sudo nano /etc/systemd/system/node_exporter.service and then add the following to the newly created file:

[Unit] Description=Node Exporter Wants=network-online.target After=network-online.target [Service] User=node_exporter Group=node_exporter Type=simple ExecStart=/usr/local/bin/node_exporter [Install] WantedBy=multi-user.target

Save and close that file. Reload systemd with the command sudo systemctl daemon-reload and then start and enable node_explorer with the following commands:

sudo systemctl start node_explorer sudo systemctl enable node_explorer

Configure Prometheus to scrape node_exporter

Let's go back to the Prometheus configuration file. Open that with the command sudo nano /etc/prometheus/prometheus.yml. At the end of that file, add the following:

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

Save and close that file. Restart Prometheus with the command:

sudo systemctl restart prometheus

At this point, Prometheus is now scraping data from node_export. If you point your browser back to http://SERVER_IP:9090 (where SERVER_IP is the IP address of the server), you can select one of the many data queries from the drop-down and execute it to reveal a graph, based on the data scraped (Figure B).

Figure B

Start scraping

You are now ready to start seriously scraping data with the help of Prometheus. This is an incredibly powerful system that can help you gather plenty of information about a host of different data points. For more information on exporters and integration, take a look at the official Prometheus site.

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