ubuntu@ubuntu:~$ docker-machine create -d virtualbox manager &&
> docker-machine create -d virtualbox worker1
Running pre-create checks...
(manager) Default Boot2Docker ISO is out-of-date, downloading the latest release...
(manager) Latest release for github.com/boot2docker/boot2docker is v18.04.0-ce
(manager) Downloading /home/ubuntu/.docker/machine/cache/boot2docker.iso from
https://github.com/boot2docker/boot2docker/releases/download/v18.04.0-ce/boot2docker.iso...
(manager) 0%....10%....20%....30%....40%....50%....60%....70%....80%....90%....100%
Creating machine...
(manager) Copying /home/ubuntu/.docker/machine/cache/boot2docker.iso to /home/ubuntu/.docker/machine/machines/manager/boot2docker.iso...
(manager) Creating VirtualBox VM...
(manager) Creating SSH key...
(manager) Starting the VM...
(manager) Check network to re-create if needed...
(manager) Found a new host-only adapter: "vboxnet0"
(manager) Waiting for an IP...
Waiting for machine to be running, this may take a few minutes...
Detecting operating system of created instance...
Waiting for SSH to be available...
Detecting the provisioner...
Provisioning with boot2docker...
Copying certs to the local machine directory...
Copying certs to the remote machine...
Setting Docker configuration on the remote daemon...
Checking connection to Docker...
Docker is up and running!
To see how to connect your Docker Client to the Docker Engine running on this virtual machine, run: docker-machine env manager
Running pre-create checks...
Creating machine...
(worker1) Copying /home/ubuntu/.docker/machine/cache/boot2docker.iso to /home/ubuntu/.docker/machine/machines/worker1/boot2docker.iso...
(worker1) Creating VirtualBox VM...
(worker1) Creating SSH key...
Wrapper Docker Machine process exiting due to closed plugin server (read tcp 127.0.0.1:37594->127.0.0.1:37131: read: connection reset by peer)
Error creating machine: Error in driver during machine creation: read tcp 127.0.0.1:37594->127.0.0.1:37131: read: connection reset by peer
ubuntu@ubuntu:~$ docker-machine ls
NAME ACTIVE DRIVER STATE URL SWARM DOCKER ERRORS
manager - virtualbox Running tcp://192.168.99.100:2376 v18.04.0-ce
worker1 - virtualbox Error Unknown machine does not exist