Alertmanager Webhook Receiver to send notifications to Discord, Telegram, and PagerDuty

Prerequisites

Install ngrok.

brew install ngrok

Ensure your System Python3 version is 3.12.

python3 -V

If your System Python is not 3.12:

brew install python@3.12
brew link python@3.12

Create a new Discord App.
Create your Discord channel where you want to receive your Alertmanager notifications.
Configure Alertmanager to send notifications to that channel.
Create a configuration file called config.yml in the same directory as the webhook script that looks like this:

---
discord:
  bot_token: YOUR_DISCORD_TOKEN
  environments:
    prod:
      warning:
        channel_id: YOUR_DISCORD_CHANNEL_ID
        author:
          name: Alertmanager
          icon_url: https://www.clipartmax.com/png/small/118-1186067_prometheus-software-logo-prometheus-monitoring.png
      critical:
         channel_id: YOUR_DISCORD_CHANNEL_ID
         author:
            name: Alertmanager
            icon_url: https://www.clipartmax.com/png/small/118-1186067_prometheus-software-logo-prometheus-monitoring.png
    test:
       warning:
          channel_id: YOUR_DISCORD_CHANNEL_ID
          author:
             name: Alertmanager
             icon_url: https://www.clipartmax.com/png/small/118-1186067_prometheus-software-logo-prometheus-monitoring.png
       critical:
          channel_id: YOUR_DISCORD_CHANNEL_ID
          author:
             name: Alertmanager
             icon_url: https://www.clipartmax.com/png/small/118-1186067_prometheus-software-logo-prometheus-monitoring.png

telegram:
  bot_token: YOUR_TELEGRAM_BOT_TOKEN
  environments:
     prod:
        warning:
           chat_id: YOUR_TELEGRAM_WARNINGS_CHAT_ID
        critical:
           chat_id: YOUR_TELEGRAM_WARNINGS_CHAT_ID

pagerduty:
   environments:
      - prod
   services:
      default: f00df00df00df00df00df00df00df00d
      website: d00fd00fd00fd00fd00fd00fd00fd00f

valid_environments:
   - test
   - prod

default_environment: prod

environment_mapping:
  us-east-1: prod
  us-east-2: test

Alertmanager Configuration

Alertmanager

alertmanager_route:
  repeat_interval: 8736h
  group_by: ['alertname', 'cluster', 'service']
  receiver: webhook-warning
  routes:
    - match:
        severity: webhook-critical
      receiver: webhook-critical
    - match:
        severity: webhook-warning
      receiver: webhook-warning

alertmanager_receivers:
  - name: webhook-critical
    webhook_configs:
      - url: "https://1d602d00.execute-api.us-east-1.amazonaws.com/alertmanager/critical"
        send_resolved: true
  - name: webhook-warning
    webhook_configs:
       - url: "https://1d602d00.execute-api.us-east-1.amazonaws.com/alertmanager/warning"
         send_resolved: true

Prometheus Rules

groups:
  - name: haproxy.rules
    rules:
      - alert: HAProxyDown
        expr: haproxy_up == 0
        for: 5m
        labels:
          severity: webhook-critical
        annotations:
          summary: "HAProxy load balancer down"
          description: "{{ $labels.job }} on {{ $labels.instance }} has been down for 5 minutes."

Testing your Webhook

Run the webhook receiver from your terminal.

python3 webhook.py

Open a new terminal window and use ngrok to create a URL that is publically accessible through the internet by creating a tunnel to the webhook receiver that is running on your local machine.

ngrok http 8090

Note that the ngrok URL will change if you stop ngrok and run it again, so keep it running in a separate terminal window, otherwise you will not be able to test your webhook successfully.
Update your Alertmanager webhook configuration to the URL that is displayed while ngrok is running (be sure to use the https one).
Trigger an Alertmanager event to trigger the notification webhook (this can be done by running the test.py script provided within this project.
Check your Discord and Telegram channels that you created for your Alertmanager notifications.

Deploy to AWS Lambda

Create a Python 3.12 Virtual Environment:

python3 -m venv venv/py3.12
source venv/py3.12/bin/activate

Upgrade pip.

python3 -m pip install --upgrade pip

Install the Python dependencies that are required by the Webhook receiver:

pip3 install -r requirements.txt

Create a file called zappa_settings.json and insert the JSON content below to configure your AWS Lambda deployment:

{
    "alertmanager": {
        "app_function": "webhook.app",
        "aws_region": "us-east-1",
        "lambda_description": "Webhook to handle Alertmanager notifications",
        "profile_name": "default",
        "project_name": "alertmanager-webhook",
        "runtime": "python3.12",
        "s3_bucket": "alertmanager-webhooks",
        "tags": {
            "service": "alertmanager-webhook"
        }
    }
}

Use Zappa to deploy your Webhook to AWS Lambda (this is installed as part of the dependencies above):

zappa deploy

Take note of the URL that is returned by the zappa deploy command, eg. https://1d602d00.execute-api.us-east-1.amazonaws.com/alertmanager (obviously use your own and don't copy and paste this one, or your Webhook will not work).

NOTE: If you get the following error when running the zappa deploy command:

botocore.exceptions.ClientError:
An error occurred (IllegalLocationConstraintException) when calling
the CreateBucket operation: The unspecified location constraint
is incompatible for the region specific endpoint this request was sent to.

This error usually means that your S3 bucket name is not unique, and that you should change it to something different, since the S3 bucket names are not namespaced and are global for everyone.

Check the status of the API Gateway URL that was created by zappa:

zappa status

Test your webhook by making a curl request to the URL that was returned by zappa deploy:

curl https://1d602d00.execute-api.us-east-1.amazonaws.com/alertmanager

You should expect the following response:

{"status":"ok"}

Update your Webhook URL in Alertmanager to the one returned by the zappa deploy command.
You can view your logs by running:

zappa tail

ashleykleynhans / alertmanager-webhook