Deployment Strategy Language Exercises

1 / 5

A DevOps engineer says: "We're using blue-green deployment — the green environment is currently live."

What happens when the new version is deployed in a blue-green strategy?

Blue-green deployment maintains two identical environments. Only one handles traffic at a time. The cutover is a DNS or load balancer switch — instantaneous for users. Rollback is equally fast: switch back to the previous environment.

Term	Meaning
blue-green cutover	The traffic switch from the old (live) environment to the new (updated) environment
zero-downtime deployment	No users experience interruption — traffic switches atomically
rollback cost	Very low — just switch traffic back to the previous environment
infrastructure cost	Higher — two full environments must be maintained simultaneously

2 / 5

A platform engineer says: "We're doing a canary deployment — the new build is serving 10% of traffic."

What is the key purpose of a canary deployment?

The canary deployment name comes from "canary in the coal mine" — a small signal of danger. A small traffic percentage routes to the new version; if metrics look good, the percentage increases. If not, rollback affects only the canary slice.

Term	Meaning
canary percentage	The fraction of traffic routed to the new version (e.g. 1%, 5%, 10%)
observation window	The monitoring period before deciding to promote or roll back the canary
promote to full rollout	Increase canary traffic to 100% after validation passes
traffic weight	The percentage split between the stable version and the canary version

3 / 5

A release note says: "The rolling deployment replaced containers one-at-a-time with the new version."

What is the main trade-off of a rolling deployment compared to a blue-green deployment?

During a rolling deployment, old and new instances coexist. If the new version has a different API shape (e.g. renamed field), requests may hit either version — causing inconsistency. Blue-green avoids this because the switch is atomic.

Concept	Rolling	Blue-green
Extra capacity	Not required	Requires 2× infrastructure
Version coexistence	Old + new run together during rollout	Atomic switch — no coexistence
N-1 compatibility	Required — must handle both API versions	Not required
Rollback speed	Slower — must redeploy old version	Instant — switch traffic back

Key vocabulary: maxSurge (max extra pods during rollout) and maxUnavailable (max pods down at once) are Kubernetes rolling update parameters.

4 / 5

A team is choosing a deployment strategy for a database migration that requires all application instances to run the new schema version simultaneously.

When should a team choose a "recreate" (big-bang) deployment strategy over rolling or blue-green?

The recreate strategy stops all old instances, then starts all new instances. This causes deliberate downtime but guarantees all instances run the same version — essential when split-version running would cause data corruption or schema conflicts.

Term	Meaning
maintenance window	A scheduled period of planned downtime communicated to users in advance
big-bang deployment	All instances updated at once — the entire version change happens in one operation
pre-upgrade migration	A database migration run before the application update to prepare the schema
planned downtime	Intentional service unavailability communicated and scheduled in advance

5 / 5

A PR description reads: "This release uses an immutable infrastructure pattern — new AMIs are built for every release."

What does "immutable infrastructure" mean in a deployment context?

Immutable infrastructure means every release produces a new server image (AMI, container image). Old instances are destroyed; new ones are created from the known-good image. This eliminates configuration drift and makes rollback simple: destroy new, launch old image.

Concept	Immutable	Mutable
Update method	Destroy and replace with new image	Patch running instances in place
Configuration drift	Impossible — each instance is identical	Likely — servers diverge over time
Rollback	Launch previous image, destroy new	Complex — reverse patches

Key vocabulary: golden image (the pre-built base image), cattle vs. pets (immutable = cattle — replaceable; mutable = pets — individually managed).