Strangler Fig in Go: Migrating a Monolith Without a Big-Bang Rewrite

Book: Hexagonal Architecture in Go Also by me: Thinking in Go (2-book series) — Complete Guide to Go Programming + Hexagonal Architecture in Go My project: Hermes IDE | GitHub — an IDE for developers who ship with Claude Code and other AI coding tools Me: xgabriel.com | GitHub You inherit a Go monolith. One repo, forty handlers, one Postgres database, two integrations stitched into the HTTP layer. Someone proposes the rewrite. Three months of design docs, a freeze on new features, a parallel repo nobody uses in production. Six months in, the rewrite is shipped to staging and abandoned because the business needed a checkout fix and there was no team left to do it. Martin Fowler called the alternative the Strangler Fig. The metaphor comes from a real plant: a fig seed sprouts in the canopy of a host tree, drops roots down the trunk, and over years grows into a hollow lattice. By the time the host tree dies, the fig is structurally complete. There is no day when the tree