Use cgswong/aws docker image to login to aws ecr. Useful when awscli is not installed.
eval $(docker run --rm \
-e AWS_ACCESS_KEY_ID=$aws_access_key_id\
-e AWS_SECRET_ACCESS_KEY=$aws_secret_access_key \
-e AWS_DEFAULT_REGION=ca-central-1 \
cgswong/aws aws ecr --no-include-email get-login)