The Caching docs says:
Note: The Docker images used for CircleCI 2.0 job runs are automatically cached on the server infrastructure where possible.
But in the Spin up Environment step of the build, we always got this:
Build-agent version 0.1.1480-7a5183d3 (2019-01-22T18:14:45+0000) Starting container ecr.foo.amazonaws.com/elixir:1.8.0 image cache not found on this host, downloading ecr.foo.amazonaws.com/elxir:1.8.0
Is this correct? There is some particular requirement for images to be cached?