How to Set Up Alertmanager for Prometheus

What Is Alertmanager?

Alertmanager handles alerts sent by Prometheus server. It takes care of deduplication, grouping, silencing, and routing alerts to the correct receiver -- whether that is email, Slack, PagerDuty, or a webhook. It is essential for a production monitoring setup on your Breeze.

Prerequisites

• A Breeze with Prometheus already installed and running
• Ubuntu 22.04 or later

Install Alertmanager

cd /tmp
wget https://github.com/prometheus/alertmanager/releases/download/v0.27.0/alertmanager-0.27.0.linux-amd64.tar.gz
tar -xzf alertmanager-0.27.0.linux-amd64.tar.gz
sudo mv alertmanager-0.27.0.linux-amd64/alertmanager /usr/local/bin/
sudo mv alertmanager-0.27.0.linux-amd64/amtool /usr/local/bin/
sudo mkdir -p /etc/alertmanager

Configure Alertmanager

Create /etc/alertmanager/alertmanager.yml:

global:
  resolve_timeout: 5m

route:
  receiver: email-alerts
  group_by: [alertname, instance]
  group_wait: 30s
  group_interval: 5m
  repeat_interval: 4h

receivers:
  - name: email-alerts
    email_configs:
      - to: admin@yourdomain.com
        from: alertmanager@yourdomain.com
        smarthost: smtp.yourdomain.com:587
        auth_username: alertmanager@yourdomain.com
        auth_password: YourSMTPPassword

Create a Systemd Service

sudo tee /etc/systemd/system/alertmanager.service <<EOF
[Unit]
Description=Alertmanager
After=network.target
[Service]
ExecStart=/usr/local/bin/alertmanager --config.file=/etc/alertmanager/alertmanager.yml
Restart=always
[Install]
WantedBy=multi-user.target
EOF
sudo systemctl daemon-reload
sudo systemctl enable --now alertmanager

Connect Prometheus to Alertmanager

Add the following to your prometheus.yml:

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

Restart Prometheus and verify the connection at the Alertmanager web UI on port 9093.