📦 NEW: Add Containerd config template support

[xrain0610]

this can use --containerd-config-template to offer a containerd template.

the template file like:

[plugins.opt]
    path = "%OPT%"
[plugins.cri]
  stream_server_address = "%NODE%"
  stream_server_port = "10010"
[plugins.cri.registry.mirrors]
  [plugins.cri.registry.mirrors."docker.io"]
    endpoint = ["https://hd.com"]

and if use cni, the cni config will append to the end.

[ibuildthecloud]

I commented here #264 (comment) but it applies to this PR too.

[uablrek]

With this PR applied I can run k3s on my laptop without internet connection. The config is below. Note that the private docker registry is unsecure ("http" instead of "https") which simplifies a lot in the setup.

[plugins.opt]
    path = "%OPT%"
[plugins.cri]
  stream_server_address = "%NODE%"
  stream_server_port = "10010"
[plugins.cri.registry.mirrors]
  [plugins.cri.registry.mirrors."docker.io"]
    endpoint = ["http://172.17.0.2:5000"]
  [plugins.cri.registry.mirrors."registry-1.docker.io"]
    endpoint = ["http://172.17.0.2:5000"]
  [plugins.cri.registry.mirrors."k8s.gcr.io"]
    endpoint = ["http://172.17.0.2:5000"]

The local registry must be pre-loaded with all images that k3s will need. I use skopeo but any way is good;

skopeo copy --dest-tls-verify=false docker://k8s.gcr.io/pause:3.1 docker://172.17.0.2:5000/pause:3.1
...

List the contents of the local registry with;

regip=172.17.0.2
for i in $(curl -s -X GET http://$regip:5000/v2/_catalog | jq -r .repositories[]); do
    echo "$i:"
    echo -n "  "
    curl -s -X GET http://$regip:5000/v2/$i/tags/list | jq -c .tags
done

[alexellis]

/subscribe 👍 (I'd like to see this and it would help k3d)

[galal-hussein]

can you catch the error here please and return err if it can't read the template

[galal-hussein]

There is no need for Value item if its nil

[galal-hussein]

Also can you rebase

[galal-hussein]

closed in favor of #381