taler-docs

prometheus-alerts.rst (5610B)

---

 ..
   This file is part of GNU TALER.
   Copyright (C) 2014-2023 Taler Systems SA
 
   TALER is free software; you can redistribute it and/or modify it under the
   terms of the GNU Affero General Public License as published by the Free Software
   Foundation; either version 2.1, or (at your option) any later version.
 
   TALER is distributed in the hope that it will be useful, but WITHOUT ANY
   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
   A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more details.
 
   You should have received a copy of the GNU Affero General Public License along with
   TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
 
   @author Javier Sepulveda
 
 Prometheus alerts
 #################
 
 .. contents:: Table of Contents
   :depth: 1
   :local:
 
 The Prometheus alert manager does periodically queries defined in the alert rules files.
 In the event that any of these conditions are met, then the alerting system will send a notification (i.e email),
 directly to the specified contact points, or towards a specific group of contact points (these are named notification policies).
 
 Very basic concepts of the Prometheus Alerting system, are explained right below. Please check the `Prometheus official
 documentation <https://prometheus.io/docs/alerting/latest/overview/>`_ , or the `Grafana documentation <https://grafana.com/docs/grafana/latest/alerting/fundamentals/>`_, if you need to get some additional information.
 
 * Alert rules: One or more queries (expresions) to measure (i.e disk space, memory, or cpu usage).
 
   - Each alert rule contains a condition with a specific threshold.
   - Each alert rule can contain a precise contact point to send the notifications to.
   - Within the same alert rule, you can specify multiple alert instances.
 
 * Contact points: This is the message notification itself, in conjunction with the specific address to send the notification to.
 
 * Notification policies: This feature allows you to gather a group different contact points, under the same label name.
 
 Install Prometheus alert manager
 ================================
 
 .. code-block:: console
 
    # apt install prometheus-alertmanager
    # systemctl start prometheus-alertmanager
    # systemctl status protheus-alertmanager
 
 Edit the Prometheus configuration file
 ======================================
 
 To make Prometheus talk with the alerting system, you need to
 speficy this, on the main prometheus configuration file.
 
 .. code-block:: yaml
 
    # Path: /etc/prometheus/prometheus.yml
    # Add this at the end of yml file
    # Alertmanager configuration
    alerting:
      alertmanagers:
        - static_configs:
            - targets: ["localhost:9093"]
 
 Alert rules configuration file
 ==============================
 
 - Create your very first first_rule.yml file.
 
   .. note::
 
      The code shown below, is just an example for CPU, disk and memory usage.
 
 .. code-block:: yaml
 
    # Path: /etc/prometheus/alert_rules.yml
    groups:
    - name: node_exporter_alerts
      rules:
      - alert: HighCPULatency
      expr: sum(rate(node_cpu_seconds_total{mode="system"}[1m])) / count(node_cpu_seconds_total{mode="system"}) * 100 > 80
      for: 1m
      labels:
       severity: warning
      annotations:
        summary: "High CPU Latency detected"
        description: "CPU latency is above 80% for more than 1 minute."
 
    - alert: LowDiskSpace
      expr: (node_filesystem_free_bytes / node_filesystem_size_bytes) * 100 < 10
      for: 1m
      labels:
        severity: critical
      annotations:
        summary: "Low Disk Space detected"
        description: "Disk space is below 10% for more than 1 minute."
 
    - alert: HighMemoryUsage
      expr: (1 - (node_memory_MemAvailable_bytes / node_memory_MemTotal_bytes)) * 100 > 80
      for: 1m
      labels:
        severity: warning
      annotations:
        summary: "High Memory Usage detected"
        description: "Memory usage is above 80% for more than 1 minute."
 
 
 Configure SMTP
 ==============
 
 .. code-block:: yaml
 
    # Path: /etc/prometheus/alertmanager.yml
 
    global:
      smtp_smarthost: 'smtp.example.com:587'
      smtp_from: 'alertmanager@example.com'
      smtp_auth_username: 'yourusername'
      smtp_auth_password: 'yourpassword'
 
    route:
      receiver: 'email'
 
    receivers:
      - name: 'email'
        email_configs:
          - to: 'recipient@example.com'
            send_resolved: true
 
 
 Add your alert rules to Prometheus
 ==================================
 
 .. code-block:: yaml
 
    #Path: /etc/prometheus/prometheus.yml
    # Add here your alert_rules.yml files
    rule_files:
       - "first_rule.yml"
       - # "second_rule.yml"
 
 
 Edit the alertmanager systemd service file
 ============================================
 
 .. code-block:: systemd
 
    # Path: /usr/lib/systemd/system/prometheus-alertmanager.service
 
    [Unit]
    Description=Alertmanager for prometheus
    Documentation=https://prometheus.io/docs/alerting/alertmanager/
 
    [Service]
    Restart=on-failure
    User=prometheus
    EnvironmentFile=/etc/default/prometheus-alertmanager
    ExecStart=/usr/bin/prometheus-alertmanager \
     --cluster.advertise-address="ip:9093" # Add this, as otherwise it won't work
    ExecReload=/bin/kill -HUP $MAINPID
    TimeoutStopSec=20s
    SendSIGKILL=no
 
    [Install]
    WantedBy=multi-user.target
 
 
 .. code-block:: console
 
    # systemctl daemon-reload
    # systemctl restart prometheus-alertmanager
    # systemctl restart prometheus
 
 Check
 =====
 
 You can check both your rules (http://ip:9090/rules) and alerts (http://ip:9090/alerts), from your web browser.