Setting Up Alert Manager on Kubernetes

AlertManager is an opensource alerting system which works with Prometheus Monitoring system. In our last article, we have explained Prometheus setup on Kubernetes.

In this guide, we will cover the Alert Manager setup and its integration with Prometheus.

Note: In this guide, all the Alert Manager Kubernetes objects will be created inside a namespace called monitoring. If you use a different namespace, you can replace it in the YAML files.

Alert Manager on Kubernetes

Alert Manager setup has the following key configurations.

A config map for Alert Manager configuration
A config Map for Alert Manager alert templates
Alert Manager Deployment
Alert Manager service to access the web UI.

Key Things To Note

You should have a working Prometheus setup up and running. Follow this tutorial for Prometheus setup ==> Prometheus Setup On Kubernetes
Prometheus should have the correct alert manager service endpoint in its config.yaml as shown below. Only then, Prometheus will be able to send the alert to Alert Manager.

alerting: alertmanagers: - scheme: http static_configs: - targets: - "alertmanager.monitoring.svc:9093"

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alerting:
   alertmanagers:
      - scheme: http
        static_configs:
        - targets:
          - "alertmanager.monitoring.svc:9093"
All the alerting rules have to be present on Prometheus config based on your needs. It should be created as part of the Prometheus config map with a file named prometheus.rules and added to the config.yaml in the following way.

rule_files: - /etc/prometheus/prometheus.rules

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rule_files:
- /etc/prometheus/prometheus.rules
Alerts can be written based on the metrics you receive on Prometheus.
For receiving emails for alerts, you need to have a valid SMTP host in the alert manager config.yaml (smarthost prameter). You can customize the email template as per your needs in the Alert Template config map. We have given the generic template in this guide.

Let’s get started with the setup.

Config Map for Alert Manager Configuration

Alert Manager reads its configuration from a config.yaml file. It contains the configuration of alert template path, email and other alert receiving configuration. In this setup, we are using email and slack receivers. You can have a look at all the supported alert receivers from here.

Create a file named AlertManagerConfigmap.yaml and copy the following contents.

kind: ConfigMap
apiVersion: v1
metadata:
  name: alertmanager-config
  namespace: monitoring
data:
  config.yml: |-
    global:
    templates:
    - '/etc/alertmanager/*.tmpl'
    route:
      receiver: alert-emailer
      group_by: ['alertname', 'priority']
      group_wait: 10s
      repeat_interval: 30m
      routes:
        - receiver: slack_demo
        # Send severity=slack alerts to slack.
          match:
            severity: slack
          group_wait: 10s
          repeat_interval: 1m

    receivers:
    - name: alert-emailer
      email_configs:
      - to: demo@devopscube.com
        send_resolved: false
        from: from-email@email.com
        smarthost: email-host-here
        require_tls: false
    - name: slack_demo
      slack_configs:
      - api_url: https://hooks.slack.com/services/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sz4Qk
        channel: '#devopscube-demo'

kind: ConfigMap

apiVersion: v1

metadata:

namespace: monitoring

data:

config.yml: |-

global:

templates:

- '/etc/alertmanager/*.tmpl'

route:

receiver: alert-emailer

group_by: ['alertname', 'priority']

group_wait: 10s

repeat_interval: 30m

routes:

- receiver: slack_demo

# Send severity=slack alerts to slack.

match:

severity: slack

group_wait: 10s

repeat_interval: 1m

receivers:

- name: alert-emailer

email_configs:

- to: demo@devopscube.com

send_resolved: false

from: from-email@email.com

smarthost: email-host-here

require_tls: false

- name: slack_demo

slack_configs:

- api_url: https://hooks.slack.com/services/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sz4Qk

channel: '#devopscube-demo'

Let’s create the config map using kubectl.

kubectl create -f AlertManagerConfigmap.yaml

1	kubectl create -f AlertManagerConfigmap.yaml

Config Map for Alert Template

We need alert templates for all the receivers we use (email, slack etc). Alert manager will dynamically substitute the values and delivers alerts to the receivers based on the template. You can customize these templates based on your needs.

Create a file named AlertManagerConfigmap.yaml and copy the contents from this file link ==> Alert Manager Template YAML

Create the configmap using kubectl.

kubectl create -f AlertTemplateConfigMap.yaml

1	kubectl create -f AlertTemplateConfigMap.yaml

Create a Deployment

In this deployment, we will mount the two config maps we created.

Create a file called Deployment.yaml with the following contents.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: alertmanager
  namespace: monitoring
spec:
  replicas: 1
  selector:
    matchLabels:
      app: alertmanager
  template:
    metadata:
      name: alertmanager
      labels:
        app: alertmanager
    spec:
      containers:
      - name: alertmanager
        image: prom/alertmanager:latest
        args:
          - "--config.file=/etc/alertmanager/config.yml"
          - "--storage.path=/alertmanager"
        ports:
        - name: alertmanager
          containerPort: 9093
        volumeMounts:
        - name: config-volume
          mountPath: /etc/alertmanager
        - name: templates-volume
          mountPath: /etc/alertmanager-templates
        - name: alertmanager
          mountPath: /alertmanager
      volumes:
      - name: config-volume
        configMap:
          name: alertmanager-config
      - name: templates-volume
        configMap:
          name: alertmanager-templates
      - name: alertmanager
        emptyDir: {}

apiVersion: apps/v1

kind: Deployment

metadata:

namespace: monitoring

spec:

replicas: 1

selector:

matchLabels:

app: alertmanager

template:

metadata:

labels:

app: alertmanager

spec:

containers:

- name: alertmanager

image: prom/alertmanager:latest

args:

- "--config.file=/etc/alertmanager/config.yml"

- "--storage.path=/alertmanager"

ports:

- name: alertmanager

containerPort: 9093

volumeMounts:

- name: config-volume

mountPath: /etc/alertmanager

- name: templates-volume

mountPath: /etc/alertmanager-templates

- name: alertmanager

mountPath: /alertmanager

volumes:

- name: config-volume

configMap:

- name: templates-volume

configMap:

- name: alertmanager

emptyDir: {}

Create the deployment using kubectl.

kubectl create -f Deployment.yaml

1	kubectl create -f Deployment.yaml

Create a Service

We need to expose the alert manager using NodePort or Load Balancer just to access the Web UI. Prometheus will talk to alert manager using the internal service endpoint.

Create a Service.yaml file with the following contents.

apiVersion: v1
kind: Service
metadata:
  name: alertmanager
  namespace: monitoring
  annotations:
      prometheus.io/scrape: 'true'
      prometheus.io/path:   /
      prometheus.io/port:   '8080'
spec:
  selector: 
    app: alertmanager
  type: NodePort  
  ports:
    - port: 9093
      targetPort: 9093
      nodePort: 31000

apiVersion: v1

kind: Service

metadata:

namespace: monitoring

annotations:

prometheus.io/scrape: 'true'

prometheus.io/path: /

prometheus.io/port: '8080'

spec:

selector:

app: alertmanager

type: NodePort

ports:

- port: 9093

targetPort: 9093

nodePort: 31000

Create the service using kubectl.

kubectl create -f Service.yaml

1	kubectl create -f Service.yaml

Now, you will be able to access Alert Manager on Node Port 31000. For example,

http://35.114.150.153:31000

1	http://35.114.150.153:31000

READ How to Install and configure Sonarqube on Linux (RHEL/Centos/ec2)

Setting Up Alert Manager on Kubernetes – Beginners Guide

Alert Manager on Kubernetes

Key Things To Note

Config Map for Alert Manager Configuration

Config Map for Alert Template

Create a Deployment

Create a Service

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