Prometheus : Set Alert Notification (Email)2022/09/09

	This is the Alert Notification Settings on Prometheus. There are many way to receive Alerts like Slack, HipChat, WeChat and others, though, on this example, Configure Alerting with Email Receiver. For more details of Alerting, Refer to the official documents. ⇒ https://prometheus.io/docs/alerting/configuration/
[1]	For Email notification, it needs SMTP Server. On this example, it based on the environment that SMTP Server is running on localhost.
[2]	Install Alertmanager on Prometheus Server Host.

root@dlp:~#

apt -y install prometheus-alertmanager

[3]	Configure Prometheus Alert Settings with Email notification.

root@dlp:~#

mv /etc/prometheus/alertmanager.yml /etc/prometheus/alertmanager.yml.org

root@dlp:~#

vi /etc/prometheus/alertmanager.yml

# create new

global:
  # SMTP server to use
  smtp_smarthost: 'localhost:25'
  # require TLS or not
  smtp_require_tls: false
  # notification sender's Email address
  smtp_from: 'Alertmanager <root@dlp.srv.world>'
  # if set SMTP Auth on SMTP server, set below, too
  # smtp_auth_username: 'alertmanager'
  # smtp_auth_password: 'password'

route:
  # Receiver name for notification
  receiver: 'email-notice'
  # grouping definition
  group_by: ['alertname', 'Service', 'Stage', 'Role']
  group_wait:      30s
  group_interval:  5m
  repeat_interval: 4h

receivers:
# any name of Receiver
- name: 'email-notice'
  email_configs:
  # destination Email address
  - to: "root@localhost"

# configure Alerting rules

root@dlp:~#

vi /etc/prometheus/alert_rules.yml

# create new

# for example, monitor node-exporter's [Up/Down]

groups:
- name: Instances
  rules:
  - alert: InstanceDown
    expr: up == 0
    for: 5m
    labels:
      severity: critical
    annotations:
      description: '{{ $labels.instance }} of job {{ $labels.job }} has been down for more than 5 minutes.'
      summary: 'Instance {{ $labels.instance }} down'

root@dlp:~#

vi /etc/prometheus/prometheus.yml

# line 17 : confirm - (Alertmanager Host):(Port)
alerting:
  alertmanagers:
  - static_configs:
    - targets: ['localhost:9093']

# line 23 : add alert rules created above
rule_files:
  # - "first_rules.yml"
  # - "second_rules.yml"
  - "alert_rules.yml"

root@dlp:~#

systemctl restart prometheus prometheus-alertmanager

root@dlp:~#

systemctl enable prometheus-alertmanager

[4]	If [node-exporter] is down, following Email is sent. (mail body is HTML)

root@dlp:~#

mail

? 1
Return-Path: <root@dlp.srv.world>
X-Original-To: root@localhost
Delivered-To: root@localhost
Received: from localhost (localhost [127.0.0.1])
        by dlp.srv.world (Postfix) with UTF8SMTP id 2CB57C092A
        for <root@localhost>; Fri,  9 Sep 2022 05:04:53 +0000 (UTC)
Subject: [FIRING:1] InstanceDown (node01.srv.world:9100 Hiroshima example critic
al)
To: root@localhost
From: Alertmanager <root@dlp.srv.world>
Message-Id: <1662699893184006303.11596023402079083712@dlp.srv.world>
Date: Fri, 09 Sep 2022 05:04:53 +0000
Content-Type: multipart/alternative;  boundary=19ff97b5fd300ca0def2e6f84c5afe7ef
06aa956192eea1932443cc0a5b3
MIME-Version: 1.0

--19ff97b5fd300ca0def2e6f84c5afe7ef06aa956192eea1932443cc0a5b3
Content-Transfer-Encoding: quoted-printable
Content-Type: text/html; charset=UTF-8
.....
.....

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