Docker-Docs/machine/concepts.md

description	keywords	title
Understand concepts for Docker Machine, including drivers, base OS, IP addresses, environment variables	docker, machine, amazonec2, azure, digitalocean, google, openstack, rackspace, softlayer, virtualbox, vmwarefusion, vmwarevcloudair, vmwarevsphere, exoscale	Machine concepts and getting help

Docker Machine allows you to provision Docker machines in a variety of environments, including virtual machines that reside on your local system, on cloud providers, or on bare metal servers (physical computers). Docker Machine creates a Docker host, and you use the Docker Engine client as needed to build images and create containers on the host.

Drivers for creating machines

To create a virtual machine, you supply Docker Machine with the name of the driver you want to use. The driver determines where the virtual machine is created. For example, on a local Mac or Windows system, the driver is typically Oracle VirtualBox. For provisioning physical machines, a generic driver is provided. For cloud providers, Docker Machine supports drivers such as AWS, Microsoft Azure, DigitalOcean, and many more. The Docker Machine reference includes a complete list of supported drivers.

Default base operating systems for local and cloud hosts

Since Docker runs on Linux, each VM that Docker Machine provisions relies on a base operating system. For convenience, there are default base operating systems. For the Oracle Virtual Box driver, this base operating system is boot2docker. For drivers used to connect to cloud providers, the base operating system is Ubuntu 12.04+. You can change this default when you create a machine. The Docker Machine reference includes a complete list of supported operating systems.

IP addresses for Docker hosts

For each machine you create, the Docker host address is the IP address of the Linux VM. This address is assigned by the docker-machine create subcommand. You use the docker-machine ls command to list the machines you have created. The docker-machine ip <machine-name> command returns a specific host's IP address.

Configuring CLI environment variables for a Docker host

Before you can run a docker command on a machine, you need to configure your command-line to point to that machine. The docker-machine env <machine-name> subcommand outputs the configuration command you should use.

For a complete list of docker-machine subcommands, see the Docker Machine subcommand reference.

Custom root Certificate Authority for Registry

if your registry is signed by a custom root Certificate Authority and it is not registered with Docker Engine, you may see the following error message:

x509: certificate signed by unknown authority

As discussed in the Docker Engine documentation place the certificates in /etc/docker/certs.d/hostname/ca.crt where hostname is your Registry server's hostname.

docker-machine scp certfile default:ca.crt
docker-machine ssh default
sudo mv ~/ca.crt /etc/docker/certs.d/hostname/ca.crt
exit
docker-machine restart

Crash reporting

Provisioning a host is a complex matter that can fail for a lot of reasons. Your workstation may have a wide variety of shell, network configuration, VPN, proxy or firewall issues. There are also reasons from the other end of the chain: your cloud provider or the network in between.

To help docker-machine be as stable as possible, we added a monitoring of crashes whenever you try to create or upgrade a host. This sends, over HTTPS, to Bugsnag some information about your docker-machine version, build, OS, ARCH, the path to your current shell and, the history of the last command as you could see it with a --debug option. This data is sent to help us pinpoint recurring issues with docker-machine and is only transmitted in the case of a crash of docker-machine.

To opt out of error reporting, create a no-error-report file in your $HOME/.docker/machine directory:

$ mkdir -p ~/.docker/machine && touch ~/.docker/machine/no-error-report

The file doesn't need to have any contents.

Getting help

Docker Machine is still in its infancy and under active development. If you need help, would like to contribute, or simply want to talk about the project with like-minded individuals, we have a number of open channels for communication.

• To report bugs or file feature requests, use the issue tracker on Github.
• To talk about the project with people in real time, join the #docker-machine channel on IRC.
• To contribute code or documentation changes, submit a pull request on Github.

For more information and resources, visit our help page.

Where to go next

• Create and run a Docker host on your local system using VirtualBox
• Provision multiple Docker hosts on your cloud provider
• Docker Machine driver reference{: target="blank" rel="noopener" class=""}
• Docker Machine subcommand reference{: target="blank" rel="noopener" class=""}