Cert Notifier Controller

Cert Notifier Controller is a Kubernetes controller built with Kubebuilder that monitors certificates issued by cert-manager and sends notifications when certificates are nearing expiration. Notifications can be sent via email, Slack, and Telegram.

Features

• Monitors certificates issued by cert-manager
• Sends notifications when certificates are within a configurable number of days from expiration
• Supports multiple notification channels: Email, Slack, and Telegram
• Secrets for sensitive information (e.g., API tokens, passwords) are securely fetched from Kubernetes secrets

Prerequisites

• Kubernetes cluster (v1.19+)
• cert-manager (v1.0+)
• Kubebuilder (v3.0+)
• Go (v1.19+)

Installation

1. Clone the repository:

   git clone https://github.com/your-username/cert-notifier-controller.git
   cd cert-notifier-controller
   

2. Build the controller:

   make build
   

3. Deploy the controller to your Kubernetes cluster:

   make deploy
   

4. Apply the CertNotification CR:

   kubectl apply -f config/samples/certmanagerapp_v1_certnotification.yaml
   

Custom Resource Definition

CertNotification

The CertNotification custom resource allows you to configure the notification settings for certificate expiration.

• expiryNotificationDays: The number of days before certificate expiration to send a notification.
• emailConfig: Configuration for email notifications.
  • smtpHost: SMTP server host.
  • smtpPort: SMTP server port.
  • from: Email address to send from.
  • to: Email address to send to.
  • password: Reference to a Kubernetes secret containing the SMTP password.
• slackConfig: Configuration for Slack notifications.
  • token: Reference to a Kubernetes secret containing the Slack API token.
  • channelID: Slack channel ID to send messages to.
• telegramConfig: Configuration for Telegram notifications.
  • botToken: Reference to a Kubernetes secret containing the Telegram bot token.
  • chatID: Telegram chat ID to send messages to.

Example CR

Here is an example of a CertNotification custom resource:

apiVersion: certmanagerapp.cert-notifier.com/v1
kind: CertNotification
metadata:
  labels:
    app.kubernetes.io/name: cert-notifier-controller
    app.kubernetes.io/managed-by: kustomize
  name: certnotification-sample
spec:
  emailConfig:
    from: "[email protected]"
    password:
      name: notification-secrets
      key: email-password
    to: "[email protected]"
    smtpHost: "smtp.example.com"
    smtpPort: "587"
  slackConfig:
    token:
      name: notification-secrets
      key: slack-token
    channelID: "your-channel-id"
  telegramConfig:
    botToken:
      name: notification-secrets
      key: telegram-bot-token
    chatID: 123456789
  expiryNotificationDays: 30