As discovered by eric.deandrea, OOTB the vscode-kubernetes-tools 1.1.0 plugin doesn't work because it depends on the yaml plugin.

So I suggested that he remove the yaml plugin and instead of the vscode-kubernetes-tools, use the camelk plugin:

use s#ms-kubernetes-tools/vscode-kubernetes-tools/latest#plugins/redhat/vscode-camelk/latest# in your devfile

And this worked:

So this suggests that the problem is that the k8s plugin has to include the yaml plugin in its meta.yaml, as does the camelk plugin:

https://github.com/redhat-developer/codeready-workspaces/blob/master/dependencies/che-plugin-registry/v3/plugins/ms-kubernetes-tools/vscode-kubernetes-tools/1.1.0/meta.yaml#L19
vs.
https://github.com/redhat-developer/codeready-workspaces/blob/master/dependencies/che-plugin-registry/v3/plugins/redhat/vscode-camelk/0.0.12/meta.yaml#L21 (contains vscode-kubernetes-tools-1.0.4)

When next we update these plugins we should make sure that all the vsix dependencies are included in the yaml.

We should also have some way of ensuring that we don't include multiple versions of the same vsix file... 1.1.0 vs. 1.0.4.