Canary Releases
Send a small slice of traffic to the new version first, then ramp up if metrics look healthy.
A canary release shifts traffic gradually. You send a small percentage — say 10% — to the new version and watch error rates and latency. If everything looks good, you ramp to 50%, then 100%. If metrics degrade, you roll back having only affected a handful of users.
Where it shines
- High-traffic services where even a brief bad release hurts many users.
- Changes you cannot fully validate in staging.
CodeDeploy offers built-in canary configurations for Lambda and ECS, such as 10% for 5 minutes, then all at once, with automatic rollback tied to CloudWatch alarms.
Example
# Shift 10% of Lambda traffic to the new version, then the rest after 5 min
aws deploy create-deployment \
--application-name myapp \
--deployment-group-name prod \
--deployment-config-name CodeDeployDefault.LambdaCanary10Percent5MinutesWhen to use it
- A team sends 5% of production traffic to a new Lambda version and monitors error rates for 10 minutes before shifting the remaining 95%.
- A company uses a canary release to test a new pricing algorithm with 1% of users before rolling it out globally, limiting financial risk.
- An ops engineer configures CodeDeploy linear traffic shifting so 10% of users are moved to the new version every minute over a 10-minute window.
More examples
Lambda canary via weighted alias
Publishes a new Lambda version and updates the prod alias to route 10% of invocations to it as a canary.
# Publish a new Lambda version
NEW_VER=$(aws lambda publish-version \
--function-name myapp \
--query 'Version' --output text)
# Shift 10% of alias traffic to the new version
aws lambda update-alias \
--function-name myapp \
--name prod \
--routing-config AdditionalVersionWeights={"$NEW_VER"=0.1}CodeDeploy linear canary config
Creates a deployment config that shifts 10% of traffic per minute so a full rollout takes 10 minutes with monitoring windows.
aws deploy create-deployment-config \
--deployment-config-name Linear10PercentEvery1Minute \
--traffic-routing-config \
type=TimeBasedLinear,timeBasedLinear='{linearPercentage=10,linearInterval=1}'Promote Lambda canary to 100%
Completes the canary by pointing the prod alias entirely to the new version, removing the traffic split.
# After verifying metrics, shift all traffic to the new version
aws lambda update-alias \
--function-name myapp \
--name prod \
--function-version $NEW_VER \
--routing-config AdditionalVersionWeights={}
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