Strangler Fig Migrations: From Observability to Shutdown

Incrementally migrating to new infrastructure by building observability before cutting traffic. A complete walkthrough using auth extraction as the running example.

Control room with side-by-side monitors comparing legacy and new system dashboard metrics for migration validation

Incrementally migrating to new infrastructure by building observability before cutting traffic. A complete walkthrough using auth extraction as the running example.

File type
PDF
Pages
46 pages
File size
2.0 MB

The strangler fig pattern trades big-bang risk for incremental progress by building the new system around the old one, shifting traffic slowly, and only decommissioning legacy when proven. The core insight: you can’t migrate what you can’t observe. Before touching any traffic, establish baselines for normal operation—metrics, response patterns, error rates. With strangler fig, each increment is a small bet. A failure at 5% traffic is containable; at 100% it becomes an outage. Big-bang migrations have single points of failure; strangler fig delivers value incrementally while you learn.

Auth extraction is the hardest extraction—if you can migrate auth, you can migrate anything.

This complete guide teaches you:

  • Migration unit selection: service boundaries and endpoint-level increments
  • Instrumentation: collecting baseline metrics before cutting any traffic
  • Traffic splitting: routing strategies and percentage-based rollout
  • Comparison testing: validating new system responses match legacy
  • Incident response during migration: rollback triggers and circuit breakers
  • Legacy decommissioning: cleanup, data archival, and final cutover
  • Real-world walkthroughs: auth, payments, and reporting services

Download Your Strangler Fig Migration Guide now to migrate without big-bang risk.

Strangler Fig Migrations: From Observability to Shutdown

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