How it works
- A proxy (API Gateway or Nginx) is placed in front of the monolith
- New features are built in new microservices
- Portions of monolith functionality are progressively moved to new services
- The proxy switches traffic from the monolithic endpoint to the new one
- When all functionality is moved, the monolith is shut down
Benefits
- Zero risk: can roll back to the monolithic endpoint at any time
- The system stays running throughout the migration
- The team gradually builds microservices experience
Alternative
Big Bang rewrite — rewrite everything at once. Statistically the most failure-prone approach for large systems.