RFC: 219 Add a new, extendable L3 ECS Service class

[nathanpeck]

• Tracking issue: #219
• Rendered version

---

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

[mergify[bot]]

Title does not follow the guidelines of Conventional Commits. Please adjust title before merge.

[davidbarsky]

Since @nathanpeck tweeted about this RFC asking for feedback, I'd like to voice my support for a more extensible L3 ECS modules. I'm a fan of this RFC and Elad's proposed feedback because this API introduces a far more gradual curve in complexity and expressiveness. I feel—hence this might be incorrect!—that there's a learning cliff with the current L3 ECS APIs, where things are great if I stay within the bounds of what is supported by API, but the moment I stray outside of those bounds, I need to drop down to the L2 APIs.

Don't get me wrong: designing an extensible and gradual API is extremely hard. It's something I've been struggling with over the past year in the libraries that I support!

[mrgrain]

This ended up being separate package https://github.com/cdklabs/cdk-ecs-service-extensions