Strangler Fig Pattern
Updated 2026-08-02
INTRODUCTION
English translation pending.
CORE DEFINITION
Named by Martin Fowler after the strangler fig, which germinates on a host tree and gradually replaces it, the pattern addresses the problem of replacing a large legacy system that cannot be rewritten in a single attempt. A facade routes traffic so that new functionality is built alongside the old system, and features are migrated one at a time until the legacy component has no remaining callers and can be removed. Key qualification: the approach requires careful handling of shared data during the transition, and premature decommissioning removes the fallback path.
SCAFFOLDING EFFECT
Reduce cognitive load
- Route at the edge: insert a facade so traffic can be directed to old or new implementations. - Migrate by slice: replace one feature at a time rather than attempting a single cutover. - Retire deliberately: delete the legacy path only after traffic and data confirm it is unused.
Anchor fast decisions
Replacing a large system in one step concentrates all the risk into a single event that is hard to test and hard to reverse. Building the replacement incrementally around the edges keeps the old system working while each new piece is validated in production, so failures stay local and reversible. The legacy system loses callers gradually until nothing depends on it and removal becomes routine.
MINIMUM ACTION
In progress 0/1Practice this model in one real situation:
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Source support: Explicit
- en.wikipedia.orghttps://en.wikipedia.org/wiki/Strangler_fig_patternverified
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