So You’ve Decided to Do a Technical Migration
summary
Migrates Monzo’s web properties from Flow to TypeScript, a multi-team effort that takes just over two years and finishes by removing Babel from the biggest app; engineers build a migration script and a package generator, run incremental migrations guided by a script that finds packages whose dependencies are ready, and publish dashboard metrics showing Flow vs TypeScript crossing over. Results: faster compile times, many former type errors fixed, CI and editor performance improve, and the approach proves workable when guarded by milestones and rollback plans.
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chapters (18)
- 0:00Technical migrations intro
- 2:26Migrated to TypeScript
- 4:02Proof of concept start
- 5:56Migration documentation
- 7:04Team organization
- 8:31Incremental vs big bang
- 9:16Using tooling to ease the process
- 11:46Progress milestones
- 13:11Slow progress challenges
- 15:32Stakeholder buy-in
- 17:16Migration risks
- 19:22Handling incidents
- 21:36Rollback plans
- 23:09Safe rollout strategies
- 24:38Finalizing TypeScript
- 25:46Migration success
- 26:06Should you migrate?
- 33:52Conclusion
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