GitOps

Prerequisite: This is the starting part of the series — no prior part is required. Later parts assume the concepts introduced here. Answer-first: PayPay scales over 100 microservices for 60+ million users in Japan by combining Domain-Driven Design boundaries with GitOps CD automation using ArgoCD and Argo Rollouts. Automated canary deployments validate new code against live production metrics before full traffic shifting. Answer-first: PayPay enforces stable deployments by combining branch promotion workflows with GitOps tools like ArgoCD. Declarative configuration files in git serve as the single source of truth, allowing ArgoCD to automatically reconcile cluster state, execute canary rollouts, and enable instant rollbacks of microservices. ...

Prerequisite: Familiarity with the concepts introduced in Part 7 — Phase2 Dual Write. Review it first if the terminology in this part is unfamiliar. Phase 3 is the final act: 100% of traffic moves to microservices, Magento becomes a passive archive, and the platform runs entirely on Go microservices via GitOps. No PHP in the critical path. No Magento license renewal needed. Answer-first: Phase 3 cutover executes an immediate 100% traffic shift for stable read services and a graduated ramp over 10 days for transactional services. Legacy Magento remains a hot standby for 30 days while automated ArgoCD gitops pipelines handle production deployments. ...

PayPay Architecture: Scaling to 70M Users & 100k Peak TPS PayPay launched in October 2018 and grew to 10 million users in just 3 months — a growth rate that no Japanese fintech had ever seen. By 2025, the platform had crossed 70 million registered users and processed 7.8 billion payments per year. Behind this growth is an engineering team that has had to scale not just their infrastructure, but their entire engineering culture: from service standardization and GitOps-driven deployments to chaos engineering and AI-powered fraud detection. ...

Argo CD 3.4 & 3.3 Guide: GitOps Upgrades & Cluster Pause (2026) GitOps is steadily becoming the gold standard for configuration management and application deployment on Kubernetes. Among the tools available, Argo CD continues to maintain its leading position. In the first half of 2026, the Argo project released two landmark versions: Argo CD 3.3 and Argo CD 3.4. These releases address numerous headaches related to application lifecycle management, synchronization performance, and incident response capabilities. ...

Autonomous Hybrid-AI Pipeline: Cron to State-Machine Production AI content pipelines need deterministic orchestrators, multi-tier memory systems, and cost-aware model routing to handle automated ingestion reliably. Replacing monolithic background jobs with event-driven agents gives resilient execution, zero-idle resource usage, and stricter output verification. This post covers four pieces of that architecture: Topology & Orchestration: Master-worker agent swarms managed by explicit state machines. Memory System Architecture: Working memory (context window), short-term memory (Redis session), and long-term memory (Vector/Graph RAG). Tool Calling & MCP: Protocol-driven tool execution via Model Context Protocol. AgentOps & Governance: Tracing, fallback cascades, evaluation gates, and hardware Wake-on-LAN power optimization. 1. Agent System Topology & State Machine A resilient pipeline replaces stateless cron scripts with an explicit Finite State Machine (FSM). By encapsulating pipeline operations within state transitions, every step—from hardware boot to scraping, filtering, and drafting—is recorded with atomic rollback safety. ...

GitOps at Scale: Kubernetes & ArgoCD for Microservices Building 21 well-architected Go microservices is only half the battle. If your deployment process relies on an engineer running kubectl apply from their laptop on a Friday afternoon, you haven’t built an enterprise platform — you’ve built a ticking time bomb. When designing this composable e-commerce ecosystem, we made one hard architectural rule from day one: no human touches the production cluster directly. Everything flows through Git. ArgoCD enforces it. Choosing EKS over ECS was a key architectural decision that enabled this first-class GitOps model; for a full cost and scaling breakdown, see our AWS EKS vs ECS Comparison. ...