Today the containers storage.conf doesn't support "drop-ins"; there was a PR to do it over here http://github.com/containers/storage/pull/1885 that needs work.

Now, the MCO's container-runtime-config-controller ends up "owning" /etc/containers/storage.conf; see https://github.com/openshift/machine-config-operator/blame/9031bd2c131c9b5902449cd291ff985cc9fdd8e9/pkg/controller/container-runtime-config/container_runtime_config_bootstrap.go

Chatting with a customer here they'd like to be able to configure additional layer stores in that file.

I think this would be a relatively simple change; we need a way to inject additional configuration there.

Option A: Modify the CRD (https://docs.openshift.com/container-platform/4.17/rest_api/machine_apis/containerruntimeconfig-machineconfiguration-openshift-io-v1.html#spec-containerruntimeconfig ) to add validated fields that render down into that TOML

Option B: Add an escape hatch for arbitrary config changes via Ignition

In this one if the user puts an /etc/containers/storage.conf in Ignition, then we'd merge that with our default one.