Deployment

What this domain actually tests

The CI/CD toolchain and, above all, deployment strategies — which is where most of the domain's marks sit.

The cast: CodePipeline orchestrates, CodeBuild builds and tests (know the buildspec.yml structure and its phases), CodeDeploy releases. CloudFormation and SAM underneath, with SAM being a shorthand transform that expands into plain CloudFormation.

The strategies are what the exam actually asks about, and it often names them literally:

• All-at-once — fastest, riskiest, brief downtime.
• Rolling — replace instances in batches.
• Blue/green — stand up a whole new environment, switch traffic, keep the old one for instant rollback.
• Canary — shift a small percentage of traffic, wait, then shift the rest.
• Linear — shift an equal increment every N minutes.

A configuration named Canary10Percent5Minutes means exactly what it says: send 10% of traffic to the new version, wait five minutes, then send the remaining 90%. Questions describe a risk appetite — "we want to catch errors on a small subset of users before full rollout" — and expect the matching name.

The traps

Blue/green means different things on different compute. On EC2, it swaps instances behind a load balancer. On Lambda and ECS, it shifts traffic by weight. Questions specify the compute platform and the strategy must match it. Candidates who learned the strategies abstractly get caught here.

Lambda versions and aliases underpin all of it. A version is immutable. An alias is a movable pointer to a version, and weighted aliases are the actual mechanism by which canary and linear traffic shifting work. $LATEST is mutable and should never be what production points at — options suggesting it are wrong.

Automatic rollback on a CloudWatch alarm is the standard answer to "roll back automatically when the error rate spikes." If a question asks for hands-off rollback, look for the alarm.

In-place deployment has no instant rollback. If the requirement mentions the ability to roll back immediately, in-place is eliminated and blue/green is almost certainly the answer.

How to study it

Deploy something. A Lambda behind API Gateway, released through CodePipeline, with an alias and a canary configuration. Then deliberately deploy a broken version and watch the alarm roll it back. That single exercise teaches you aliases, weights, alarms, and rollback in one sitting, and all four are tested.

Then build a small grid on paper: compute platform down the side (EC2, ECS, Lambda), strategies across the top, and which combinations are valid. The exam lives in that grid, and it is a twenty-minute job to fill in.

At 24% of the exam, deployment is worth roughly sixteen questions — and unlike the reasoning-heavy parts of AWS exams, most of them are decided by facts you can simply learn.