Complete Kubernetes operator implementation that integrates Resend email service with the Milo platform for automated email delivery.

Architecture

• Controller Manager: Reconciles Email CRDs by fetching templates, rendering content, and sending emails via Resend

• Webhook Server: Processes Resend delivery events (sent/delivered/bounced) and updates Email status

• Email Provider Interface: Abstracted email provider supporting multiple backends (currently Resend)

Key Features

• Template Rendering: Dynamic email content using EmailTemplate CRDs with variable substitution

• Idempotency: Uses Email UID as idempotency key to prevent duplicate sends

• Status Tracking: Kubernetes conditions for email delivery states (Pending/Delivered/Failed)

• Event Correlation: Indexes emails by providerID for efficient webhook event processing

• Priority Support: Configurable retry delays based on email priority

• Security: SVIX webhook signature verification for event authenticity

Components

• Dual-mode deployment: controller manager + separate webhook server

• RBAC for Email, EmailTemplate, and User CRD access

• Metrics and health endpoints with TLS support

• Leader election for HA deployments

Provides reliable, observable email delivery for the Milo notification system.