Canary deployments

**Tell us about your request**
What do you want us to build?

Whilst there is currently Blue/Green deployments, it would be good if there was support for canary releases (eg how API Gateway REST offers)

**Describe alternatives you've considered**
A clear and concise description of any alternative solutions or features you've considered.

Lambda@Edge

**Additional context**
Anything else we should know?

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