sdk_container/containerd: Add registry config_path

[nikParasyr]

sdk_container/containerd: Add registry config_path

Update containerd config to include the crio registry plugin that defines the config_path. This allows users to add host specific configuration for containerd without having to overwrite the default containerd config.

How to use

This config allows users to easily drop in hosts file under etc/containerd/certs.d as explained here, in order to configure registry specific configs (mirrors, header, skip_tls, ... )

Testing done

have to use the service override mechanism to change the default config file of containerd. Copied the containerd config of the MR into /etc/containerd/config.toml. Restarted containerd and after that:

• if the /etc/containerd/certs.d directory does not exist or is empty, containerd does NOT have any issues

• I was then able to add hosts files based on the examples above and create mirrors

• Changelog entries added in the respective changelog/ directory (user-facing change, bug fix, security fix, update)

• Inspected CI output for image differences: /boot and /usr size, packages, list files for any missing binaries, kernel modules, config files, kernel modules, etc.

Resolves: flatcar/Flatcar#583

[nikParasyr]

I have 2 remarks/questions about this:

• is this the right location of the files? They have not been touched for 2y and similar with the changelog, so im not sure this is the right place, but going over the various repos i couldnt find a different place
• in the alpha releases you include containerd version 2 which support config version 3. The configuration of this plugin is different in version 3 and version 2 as shown here. In the files i edited i saw version 2 so i added the config of that version