containerd configuration for kubeadmConfigSpec overwrites Flatcar containerd config

[heytrav]

As with #138 I am attempting to build a Flatcar cluster by overriding the defaults with my own -f values.yaml.

Expected result

When I build a Flatcar cluster I expect the /etc/containerd/config.toml file to have the following content from the image builder template

## template: jinja

# Use config version 2 to enable new configuration fields.
# Config file is parsed as version 1 by default.
version = 2

imports = ["/etc/containerd/conf.d/*.toml"]

[plugins]
  [plugins."io.containerd.grpc.v1.cri"]
    sandbox_image = "registry.k8s.io/pause:3.9"
  [plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc]
    runtime_type = "io.containerd.runc.v2"
  [plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc.options]
    SystemdCgroup = true

Actual result

The cluster control plane fails to reach a healthy state.

When I log in to a control plane node I see the following:

trav-fc-refactor-38-control-plane-7752499b-j27jg ~ # cat /etc/containerd/config.toml 
[plugins."io.containerd.grpc.v1.cri".registry]
config_path = "/etc/containerd/certs.d

The openstack-cluster.kubeadmConfigSpec.containerd block executes a number of file operations including appending configuration to /etc/containerd/config.toml. This appears to overwrite the containerd config completely rather than just appending to the end of the file.

If I remove the file block here https://github.com/stackhpc/capi-helm-charts/blob/b643ff30f8541f055a471f237e28daf40fd7a273/charts/openstack-cluster/templates/_helpers.tpl#L206-L212 the contents of the containerd/config.toml file are as I expect and containerd starts normally.

[heytrav]

Here is the section of my values.yaml which I am using to override controlplane and nodegroup values for Flatcar.