Unable to evaluate output of docker-env: Command 'docker' not found

[staticdev]

Fresh installed minikube on Ubuntu 18.10:

curl -Lo minikube https://storage.googleapis.com/minikube/releases/latest/minikube-linux-amd64 \
  && chmod +x minikube
sudo cp minikube /usr/local/bin && rm minikube

• How to reproduce the error (just 3 commands):
  minikube start

😄 minikube v1.0.0 on linux (amd64)
🤹 Downloading Kubernetes v1.14.0 images in the background ...
💡 Tip: Use 'minikube start -p ' to create a new cluster, or 'minikube delete' to delete this one.
🏃 Re-using the currently running virtualbox VM for "minikube" ...
⌛ Waiting for SSH access ...
📶 "minikube" IP address is 192.168.99.100
🐳 Configuring Docker as the container runtime ...
🐳 Version of container runtime is 18.06.2-ce
⌛ Waiting for image downloads to complete ...
✨ Preparing Kubernetes environment ...
🚜 Pulling images required by Kubernetes v1.14.0 ...
🔄 Relaunching Kubernetes v1.14.0 using kubeadm ...
⌛ Waiting for pods: apiserver proxy etcd scheduler controller dns
📯 Updating kube-proxy configuration ...
🤔 Verifying component health .....
💗 kubectl is now configured to use "minikube"
🏄 Done! Thank you for using minikube!

eval $(minikube docker-env)
docker ps

I get in respose:

Command 'docker' not found, but can be installed with:

sudo snap install docker # version 18.06.1-ce, or
sudo apt install docker.io

See 'snap info docker' for additional versions.

[staticdev]

I've confirmed docker is a requirement to run minikube. So it is a documentation issue.

[afbjorklund]

You need a container runtime, there are several to choose from. Docker is the default.

[afbjorklund]

Note that what we document is installing kubectl, and using that to talk to the cluster.
Using docker and docker-env is an advanced topic, and not available everywhere...

As a workaround you can use minikube ssh, and then run the commands on the VM ?
But anyway, you don't absolutely need a docker client - but should be documented anyway.

[staticdev]

I think there should be something like:

"

Install a container runtime

Docker is the most common choice, but minikube also works with containerd. CRI-O and rkt.
"

On this page even before install kubectl or hypervisor since the main purpose is container orchestration and minikube doesn't come by default with a runtime.

I didn't find this documentation on github to make a pull request.

[afbjorklund]

Well, there is a runtime (or three) on the VM - it just doesn't come with a local runtime ? What could be needed, however, is a better way to build new images, than doing it directly on the control plane node.

The current approach is more of a hack, and I guess it could mention that you need to install docker:
https://github.com/kubernetes/minikube/blob/master/docs/reusing_the_docker_daemon.md

(Mirrored at: https://kubernetes.io/docs/setup/minikube/#use-local-images-by-re-using-the-docker-daemon)

As long as we recommend that approach, we should add a link to: https://docs.docker.com/install/
And probably mention that you only need the Docker client, not the entire daemon and everything.

[afbjorklund]

If you want to do other interaction with the CRI directly, the recommend approach is now crictl:

$ minikube ssh -- sudo crictl ps

That will work for all of the runtimes, including Docker. But it doesn't have a local/remote client/server.

It would perhaps be interesting to see if there are any more uses of a local docker, not covered by crictl ?

[tstromberg]

I've confirmed docker is a requirement to run minikube. So it is a documentation issue.

As someone who does not have docker installed, I can definitely say docker is not a requirement to run minikube. It is however required for the docker-env command, which makes sense.

As afbjorklund mentions, we do however include it within the minikube VM.

[tstromberg]

Closing, as minikube doesn't actually invoke docker.

[staticdev]

@tstromberg minikube doesn't invoke docker, but it's documentation (https://kubernetes.io/docs/tasks/tools/install-minikube/) is misleading with this information without saying installing docker on the host machine is a prerequisite to run those commands...

[afbjorklund]

Documenting it on the docker-env page makes sense. Probably can leave the details on how, to Docker Inc.