ECS/ECR: is common practice to have one registry per image (and associated versions)?
Yes. And also, possibly, no.
You push images to ECR. How you configure your image is up to you. Ideally, you'd have an image with a single responsibility, but this is your decision.
If you have multiple images, you push to multiple ECRs. If you have a single image doing many things, you can get away with a single ECR.
You can also push multiple images to the same ECR with creative use of tags (e.g. having the "image name or flavour" in the tag using your own naming convention.
- It is recommended to push images with the version number of the same type.
For example your-repo:1.1, your-repo:1.2
If you push images with the same that exist in the ECR repository than your old image will be replaced with the new image you are pushing.
- It depends on how your application is working. It is always advised to separate container working logically separate.
For example The database image with a persistence volume. So, If a database container dies than it would not affect your data.