Release Strategies
Blue-green, canary, shadow and progressive delivery.
5 to work through
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advanced
A brokerage must deploy without disrupting customers who may be mid-transaction. Which release strategy fits, and what does it require?
2 min answer -
advanced
A collaborative product with long-lived client connections needs zero-downtime releases. How do rolling, blue-green and canary differ here?
2 min answer -
advanced
A regulated business releases every two weeks through a change advisory board. Engineering wants continuous deployment. The control is real: an auditor tests that every production change was authorised, risk-assessed, tested and reversible. Sequence the migration.
3 min answer -
advanced
At 14:05 a canary on 5% of traffic passes automated analysis across 60 metrics and is promoted. At 14:40 the fleet error rate is 12 times baseline. The canary's own dashboards were clean the entire time. What made the canary blind, and which design decision allowed it?
3 min answer -
advanced
You roll back a deployment and the system is still broken. What are the likely reasons?
2 min answer
2 terms in this topic
Blue-Green Database Schema
The constraint that makes fast rollback actually work — both application versions must be able to run against one schema at the same time.
patternRelease Strategies
How new code reaches users — rolling, blue-green, canary, or flag-controlled — chosen by rollback speed and blast radius.
Neighbouring topics
Software Architecture
General material on the engineering underneath an architecture.
SOLID
Five design principles, two of which scale beyond the class.
Domain-Driven Design
Ubiquitous language, bounded contexts and context mapping.
Bounded Contexts
Where one model ends and another begins, and why forcing one fails.
Clean Architecture
Concentric layers with dependencies pointing only inwards.
Hexagonal Architecture
Ports defined by the domain, adapters supplied by infrastructure.
Microservices
Independent deployability, and the distributed problems it buys.
Modular Monolith
Enforced internal boundaries without a network between them.
Service Boundaries
Drawing lines along change patterns rather than technical layers.
Design Patterns
Reusable solutions at code level, and when they become ceremony.
Refactoring
Changing structure without changing behaviour, in verified steps.
Technical Debt
Deliberate, tracked and repaid — as distinct from mess.
Testing Strategies
The pyramid, and the contract tests distributed systems add to it.
Contract Tests
Capturing what consumers actually use, not what the API documents.
CI/CD
Continuous integration and delivery, and the architecture that caps them.
Feature Flags
Decoupling deploy from release, with an expiry date.
Trunk-Based Development
Short-lived branches, and unmerged work as inventory.
Code Review
Where architectural rules are enforced by people rather than by tools.
DORA Metrics
Throughput and stability moving together rather than trading off.