Cloud Migration

Zero-Downtime Legacy Modernization Runbook

Step-by-step procedures for transitioning legacy monolithic applications to Next.js and Neon PostgreSQL without dropping live customer traffic.

Executive Summary

Detailed operational runbook utilizing the Strangler Fig pattern and reverse proxy routing to modernize mission-critical systems safely.

Catalog all indexed legacy endpoints, parameter strings, and canonical URLs.

Deploy an edge reverse proxy to split incoming traffic by route path.

Build and verify the first target module in Next.js and serverless PostgreSQL.

Establish real-time bi-directional database synchronization between legacy and modern tables.

Route progressive canary traffic to the new module and monitor error rates.

Permanently decommission legacy components after 30 days of error-free operation.

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