To step through this recipe, you will need the following:

Let's say you want to store your application container in a repository named myapp, so you can deploy it easily. It's very simple with Terraform. Add the following code to a file named ecr.tf:

resource "aws_ecr_repository" "myapp" {
  name = "myapp"
}

If you want to know the URL to access your new repository, you can create an output using the corresponding exported attribute:

output "ECR" {
  value = "${aws_ecr_repository.myapp.repository_url}"
}

If you're used to the other Docker registries, the first step is to authenticate so you create private repositories. Here, no login or password are provided by AWS. We need to use the official AWS command line to authenticate, and that will give us temporary Docker credentials. The output of this command is the Docker command to type:

$ aws ecr get-login --region eu-west-1
docker login -u AWS -p AQECAHh... -e none https://<account_number>.dkr.ecr.eu-west-1.amazonaws.com

Now we can docker build, tag, and push images at will! (See more about using Docker images in the dedicated chapter of this book.)

A nice advanced feature is the ability to use fine-grained policies for each repository created.