progressive-delivery

name	progressive-delivery
description	Choose and wire a progressive-delivery strategy — blue-green, canary, rolling, or feature-flagged — by blast radius and reversibility, with a health-gated promotion and an automated, rehearsed rollback.

Progressive Delivery

Purpose: ship to production safely by matching the rollout to the risk.

Strategy by blast radius

Situation	Strategy
Stateless, fast rollback	Canary (1% -> 10% -> 100% on signal)
Need instant cutover/rollback	Blue-green
Risky/irreversible behaviour change	Feature flag (deploy dark, release later)
Schema change	Expand/contract migration before the deploy

The health gate

A canary promotes on an SLO / error-budget burn-rate signal from observability-sre, not a timer. Define the abort condition and the rollback action before you ship, and rehearse the rollback.

Deploy != release

Separate them: deploy the bytes dark, flip the flag to release. A bad release becomes a flag flip.