Reference Material:

https://docs.aws.amazon.com/codedeploy/latest/userguide/reference-appspec-file-structure-resources.html#reference-appspec-file-structure-resources-ecs
TaskDefinition – Required. This is the task definition for the Amazon ECS service to deploy. It is specified with the ARN of the task definition. The ARN format is arn:aws:ecs:aws-region:account-id:task-definition/task-definition-family:task-definition-revision. For more information, see Amazon Resource Names (ARNs) and AWS service namespaces.
ContainerName – Required. This is the name of the Amazon ECS container that contains your Amazon ECS application. It must be a container specified in your Amazon ECS task definition.
ContainerPort – Required. This is the port on the container where traffic will be routed to.
https://docs.aws.amazon.com/codedeploy/latest/userguide/reference-appspec-file-structure-resources.html
"
resources:
- name-of-function-to-deploy:
type: "AWS::Lambda::Function"
properties:
name: name-of-lambda-function-to-deploy
alias: alias-of-lambda-function-to-deploy
currentversion: version-of-the-lambda-function-traffic-currently-points-to
targetversion: version-of-the-lambda-function-to-shift-traffic-to
"