Error: Failed to load middleware configuration from config/middleware.json

When starting a KrakenJS application, a missing or malformed config/middleware.json triggers the error “Failed to load middleware configuration from config/middleware.json”. This prevents the process from booting and forces a restart after the file is corrected. The team wishes to move existing Express‑style middleware definitions into Kraken’s declarative format while maintaining zero‑downtime deployments behind a load balancer.

Constraints include keeping session stores and database connections compatible across versions, avoiding any increase in startup latency that could lengthen the cutover window, and preserving the ability to adjust middleware without redeploying the whole service. It is unclear whether the declarative JSON approach or retaining programmatic app.use calls better satisfies these goals.

What are the comparative impacts on startup time and error resilience between the two middleware definitions? How does each option affect the feasibility of hot‑swapping instances during a rolling update? Which strategy reduces the likelihood of encountering the configuration‑load error during the migration window?