How docker commands are invoked using kubectl?

[pritesh.c...@apcera.com]

When we deploy a kubernetes cluster, we can see that docker engine is running on the nodes.
When we create a pod using kubernetss command and using a docker image, we can see the process using the docker ps command. This means kubectl is using the same docker engine somehow.

I have set "export DOCKER_CONTENT_TRUST=1" in the vagrant file itself and deployed the kubernetes cluster. I logged-into the nodes and verified that the environment is imported.

When I try to run a docker base container using "kubectl run --image docker/trusttest:latest <name>" command it works fine. But when I run the same image using "docker run docker/trusttest:latest" this gives me an error that the image is not signed.

So my question is: what is the docker engine which kubectl is pointing to is not the same as the docker engine running locally on the nodes. Is there any change I have to do or the way I am doing it is different?