Gremoire

Setting Up Prometheus on a VPS for Monitoring and Alerting ​

Prometheus is a powerful monitoring and alerting tool designed for cloud infrastructure, servers, and applications. If you're hosting a VPS (Virtual Private Server) and want to monitor metrics like CPU, memory, disk usage, web server health, and custom application metrics, this guide will walk you through setting up Prometheus, Grafana, and Alertmanager with NGINX reverse proxy for web access.

1. VPS Requirements ​

Before starting, ensure your VPS meets the following:

  • Ubuntu 20.04+ (or similar Linux distribution)
  • Minimum 2GB RAM (for smooth performance)
  • Root or sudo access
  • Firewall configured (if using UFW, allow required ports)

2. Install Prometheus ​

Step 1: Create Prometheus User ​

bash
sudo useradd --no-create-home --shell /bin/false prometheus
sudo mkdir /etc/prometheus /var/lib/prometheus

Step 2: Download and Install Prometheus ​

bash
cd /opt
wget https://github.com/prometheus/prometheus/releases/latest/download/prometheus-linux-amd64.tar.gz
tar xvf prometheus-linux-amd64.tar.gz
sudo mv prometheus-*/ /usr/local/bin/prometheus
sudo chown prometheus:prometheus /usr/local/bin/prometheus /etc/prometheus /var/lib/prometheus

Step 3: Configure Prometheus ​

Create a configuration file at /etc/prometheus/prometheus.yml:

yaml
global:
  scrape_interval: 5s

scrape_configs:
  - job_name: 'node_exporter'
    static_configs:
      - targets: ['localhost:9100']

  - job_name: 'web_app'
    static_configs:
      - targets: ['localhost:5000']

alerting:
  alertmanagers:
    - static_configs:
        - targets: ['localhost:9093']

3. Install and Configure Alertmanager ​

Step 1: Download Alertmanager ​

bash
cd /opt
wget https://github.com/prometheus/alertmanager/releases/latest/download/alertmanager-linux-amd64.tar.gz
tar xvf alertmanager-linux-amd64.tar.gz
sudo mv alertmanager-*/ /usr/local/bin/alertmanager
sudo mkdir /etc/alertmanager /var/lib/alertmanager
sudo chown prometheus:prometheus /usr/local/bin/alertmanager /etc/alertmanager /var/lib/alertmanager

Step 2: Configure Alertmanager ​

Create /etc/alertmanager/alertmanager.yml:

yaml
global:
  resolve_timeout: 5m

route:
  receiver: 'email-notifier'

receivers:
  - name: 'email-notifier'
    email_configs:
      - to: 'your-email@example.com'
        from: 'alertmanager@example.com'
        smarthost: 'smtp.gmail.com:587'
        auth_username: 'your-email@example.com'
        auth_password: 'your-email-password'

4. Install and Configure Grafana ​

Step 1: Install Grafana ​

bash
sudo apt install -y adduser libfontconfig1
wget https://dl.grafana.com/oss/release/grafana_10.0.0_amd64.deb
sudo dpkg -i grafana_10.0.0_amd64.deb
sudo systemctl enable grafana-server
sudo systemctl start grafana-server

Step 2: Access Grafana ​

Grafana runs on port 3000. To access it:

  • Open http://your-vps-ip:3000/
  • Default credentials: admin / admin

5. Install Node Exporter (System Metrics) ​

bash
cd /opt
wget https://github.com/prometheus/node_exporter/releases/latest/download/node_exporter-linux-amd64.tar.gz
tar xvf node_exporter-linux-amd64.tar.gz
sudo mv node_exporter-*/ /usr/local/bin/node_exporter

Run Node Exporter:

bash
/usr/local/bin/node_exporter &

6. Set Up NGINX Reverse Proxy ​

Step 1: Install NGINX ​

bash
sudo apt update
sudo apt install nginx -y

Step 2: Configure NGINX ​

Edit /etc/nginx/sites-available/prometheus:

nginx
server {
    listen 80;
    server_name your-server-ip;

    location /prometheus/ {
        proxy_pass http://localhost:9090/;
    }

    location /grafana/ {
        proxy_pass http://localhost:3000/;
    }

    location /alertmanager/ {
        proxy_pass http://localhost:9093/;
    }
}

Enable the site and restart NGINX:

bash
sudo ln -s /etc/nginx/sites-available/prometheus /etc/nginx/sites-enabled/
sudo systemctl restart nginx

Now you can access:

  • Prometheus → http://your-vps-ip/prometheus/
  • Grafana → http://your-vps-ip/grafana/
  • Alertmanager → http://your-vps-ip/alertmanager/

7. Enable HTTPS with Let's Encrypt (Optional) ​

bash
sudo apt install certbot python3-certbot-nginx -y
sudo certbot --nginx -d your-domain.com

Now your services will be accessible via HTTPS.

8. Create an Alert for Web Server Downtime ​

Modify /etc/prometheus/alerts.yml:

yaml
groups:
  - name: server_status_alerts
    rules:
      - alert: WebServerDown
        expr: up{job="web_app"} == 0
        for: 1m
        labels:
          severity: critical
        annotations:
          summary: "Web server is down"
          description: "The monitored web application has been down for more than 1 minute."

Reload Prometheus:

bash
sudo systemctl restart prometheus

Congratulations! ​

You now have:

Prometheus for monitoring
Grafana for visualization
Alertmanager for notifications
NGINX for secure access

If you need custom queries, dashboards, or alert integrations, feel free to ask! 🚀