Comparison
Artefact promotionvsEnvironment parity
Artefact promotion
the same version moves from staging to production by changing a reference, and no build runs to make that happen.
Advancing a specific artefact version through a sequence of environments as it earns confidence. It makes the question 'what is in production' answerable and gives rollback an obvious target — the version that was there before. Where promotion is implemented as a rebuild from a branch, none of those properties hold, which is the main practical reason branch-per-environment schemes go wrong.
Full entry →Environment parity
it worked in staging and broke in production, because staging had one replica, no mesh and a different database size.
How closely lower environments resemble production in configuration, topology, data shape and scale. Perfect parity is unaffordable, so the useful discipline is knowing exactly where the differences are and which classes of bug those differences will therefore let through. Undocumented divergence is what turns a green staging run into false confidence.
Full entry →