Docker Machine on Windows

After having so much fun with running Docker in a Virtualbox VM, I decided to explore Docker's solution to running Docker on Windows. Turns out, there's really not much different, apart from using 'docker-machine create' to link Windows Docker commands to the VM one.

I run the Docker Quickstart terminal, which creates a 'default' VM under IP 192.168.99.100, with Docker installed and daemon running on port 2376. It has a NAT Network Adapter, with a randomly forwarded port (e.g. 56858) to guest port 22. It also creates a Host-Only Network Adapter in Virtualbox, named "Virtualbox Host-Only Ethernet Adapter", and this has a DHCP server enabled to distribute IPs. The adapter has an IP address of "192.168.99.1". The rest looks like this:

I had to figure all this out myself, and I really wish all this information was just laid out from the start on the Docker documentation.

My goal was to create a Virtualbox VM, and hook up Windows Docker commands to it. This gives me the flexibility of starting a VM via Vagrant, and not having to use boot2docker OS. Seems logical to me.

First, this line is required in Vagrantfile:

config.vm.network "private_network", type: "dhcp"

This will create a Host-Only network for you, meaning the VM will have an IP assigned by Virtualbox's DHCP server. I don't know about you, but I get an automatically assigned IP: 172.28.128.1

Then you need to somehow automatically determine this IP. You can use this:

"vagrant ssh -c "ip address show eth1 | grep 'inet ' | sed -e 's/^.inet //' -e 's/^([0-9.]+)./\1/'"

Note how I assume 'eth1'. This is because I expect to only have 2 adapters, and eth0 is used by the NAT adapter.

Knowing the IP of your VM, you can run this on Windows (you must pass in the private key to generic-ssh-key):

docker-machine -D create --driver generic --generic-ssh-user root --generic-ssh-key myfolder/id_rsa --generic-ip-address 172.28.128.4 --generic-ssh-port 22 myserver

But then you may encounter this:

Error running SSH command: exit status 127

This actually requires you to put your public key into the 'authorized_keys' file for that user (in my case, root) on your VM.

After that, you may get this:

Reading server key from C:\Users\Alkaiser\.docker\machine\machhefserver\server-key.pem
Error creating machine: Error checking the host: Error checkinor regenerating the certs: There was an error validating certis for host "172.28.128.4:2376": dial tcp 172.28.128.4:2376: i/out
You can attempt to regenerate them using 'docker-machine regencerts [name]'.
Be advised that this will trigger a Docker daemon restart whic stop running containers.

Other users suggest you have a conflicting Host-Only adapter. I wouldn't rule this out, however it is more likely your TCP connection is being blocked. You can validate this by running "telnet 172.28.128.4 2376". This should connect because the Docker daemon is listening on that port. If this doesn't work, it means your VM is blocking that port. On CentOS7, I unblock it by using:

firewall-cmd --permanent --zone=public --add-port=2376/tcp; systemctl restart firewalld

Now you should get (with debug output):

Docker is up and running!
Reticulating splines...
(chefserver) Calling .GetConfigRaw
To see how to connect your Docker Client to the Docker Engine g on this virtual machine, run: D:\Program Files\Docker Toolboer-machine.exe env chefserver
Making call to close driver server
(chefserver) Calling .Close
Successfully made call to close driver server
Making call to close connection to plugin binary
Making call to close driver server
(flag-lookup) Calling .Close
Successfully made call to close driver server
Making call to close connection to plugin binary

Have fun with your custom Docker machine!