add Makefile to build and push to ECR

[ltagliamonte]

simple Makefile to simplify the build and push to AWS ECR repo.
Would love to see an official build in docker repo.

[sinkingpoint]

I'd rather not have the ECR stuff by default - will work on a docker hub build today, but ECR is org specific enough that I'd rather leave that up to consumers of the repo rather than including it by default

[ltagliamonte]

Sure it is just an helper other contribution could add other docker repositories

[sinkingpoint]

My point is that we don't want to be managing the code for each and every custom repository that people want to push to - that is out of the scope of this - the ECR stuff can exist outside this repo, it doesn't belong here

[ltagliamonte]

@sinkingpoint any update on the official docker hub image?

[sinkingpoint]

Yep - apologies for the delay. https://hub.docker.com/r/sinkingpoint/prometheus-gravel-gateway