Approval Workflow Engine (Go, PostgreSQL, Redis, React, gRPC, Docker) overview

A workflow engine purpose-built for multi-step approval processes such as expense approvals, access requests, and change advisory boards. Go implements the core state machine, with PostgreSQL storing workflow definitions, instance state, and audit trails as immutable event logs. Redis provides distributed locking for concurrent workflow transitions and caches active workflow graphs. gRPC enables efficient service-to- service integration, while a React frontend renders dynamic approval forms and status dashboards. Prometheus tracks workflow throughput and SLA compliance. Docker containers deploy the complete system. The tradeoff is the complexity of modeling arbitrary approval topologies (parallel, sequential, conditional) while maintaining audit integrity.