Infrastructure Modernization and Security Foundation

Tasks

• •Established Kubernetes operations through an ECS-to-EKS migration and built an ArgoCD-based GitOps deployment flow connecting builds, deployments, and completion notifications
• •Worked on AWS-to-GCP service migration, moving backend, web, and notification services to GKE and adapting deployment, cache connections, and authentication to the new environment
• •Migrated STT inference traffic from EKS GPUs to a shared Mac Studio to reduce GPU costs
  • •Estimated baseline compute cost for two always-on GPU nodes at US$470–630/month using published minimum Seoul Spot rates and 730 hours per month
  • •Built a whisper.cpp and Metal transcription server with a gateway compatible with the existing API, and switched production and non-production processing paths
  • •Compared transcription quality using English and Japanese audio, and verified transcription, subtitle generation, and diagnostic reports for actual lessons
• •Used a WAF to block web attacks and managed security rules with Terraform, moving credentials into a secrets management service instead of storing them in code
• •Decoupled notification storage from DynamoDB through a storage interface and implemented a Firestore adapter and data migration tools
  • •Designed for compatibility with existing queries, conditional updates, and scheduled-notification behavior, and wrote emulator-based regression tests
  • •Implemented backfill, incremental synchronization, and pre-migration checks; disabled queue consumers and schedulers during migration to separate it from live notification delivery
• •Built an LGTM observability stack to reduce Datadog cost, connecting logs, traces, and metrics through MDC and trace IDs
  • •Stabilized migrated services by adjusting JVM memory, resource settings, and log and metric collection paths for GKE

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