Blue-Green vs Canary vs Rolling: Deployment Strategies Compared

Three deployment strategies; three different bets on blast radius vs cost.

What each does

Blue-green: stand up V2 alongside V1; cut over atomically.

Canary: ramp V2 gradually; watch metrics; abort if degraded.

Rolling: replace pods incrementally; default in Kubernetes.

Cost per strategy

• Blue-green: 2x infrastructure during cutover.
• Canary: 1.05-1.3x during ramp.
• Rolling: 1x or slightly above; the cheapest.

Rollback story

Blue-green: instant; flip the load balancer.

Canary: instant for newly-promoted percentage; existing traffic unaffected.

Rolling: minutes; depends on rollout cadence.

Picking correctly

Blue-green for: schema migrations; breaking API changes; expensive validation.

Canary for: most deploys; user-impact observable.

Rolling for: routine deploys; mature health-check coverage.

Antipatterns

• Blue-green for routine deploys. Pay for capacity you do not need.
• Canary without good metrics. Cannot detect when to abort.
• Rolling with bad health checks. Bad pods replace good ones silently.

What to do this week

Three moves. (1) Apply this to one pipeline first. (2) Measure deploy frequency / MTTR before/after. (3) Document the outcome so the next team starts from data.