What is Canary Deployment? — UK Software Development Guide
Direct Answer
A canary deployment is a release strategy where a new version of software is deployed to a small subset of users or servers (the "canaries") before being rolled out to the full user base. If the canary deployment shows no issues (errors, performance degradation, user complaints) over a defined period, the rollout continues to 100%. If issues are detected, the canary is rolled back with minimal user impact.
Canary-deployment in the UK
Canary deployments support FCA operational resilience requirements. Rather than a full deployment that could impact all users if problematic, canary deployments limit blast radius to 1–5% of users — maintaining service within impact tolerances. For NHS clinical software: canary deployments enable testing of new versions with low-risk user cohorts before exposing clinical workflows to changes. Feature flags and Kubernetes traffic management (Argo Rollouts, Flagger) are the most common technical implementations in the UK market.
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