SPECIAL SNEAK PREVIEW OF DOCKER MACHINE 0.3.0
Welcome to the Machine.
It’s release season and the incorrigible Evan Hazlett and I, along with many others whose work I am infinitely appreciative for and could not possibly do without, are firing on all cylinders to try and get the best possible Docker Machine that we can out the door for the 0.3.0 release. There are so many new features and so much goodness in this release that I couldn’t possibly do them all justice in a single blog post (although I may well try for the release post), but since I am bursting at the seams with enthusiasm for it I can’t help but possibly “spill the beans” on one of the things we are getting ready to drop and give you a little sneak preview.
We’re introducing a new driver in this release called
generic. It seems like
a really subtle (albeit useful) feature at first, but I have a feeling it’s
going to be really important to the future of the project, and in my opinion
really hearkens to all kinds of insanely awesome new things which are starting
to become viable – particularly, integration with other projects that
previously seemed to overlap in functionality with Machine, or where the
boundaries weren’t quite clear. More on the specifics of that in a later post.
Go doesn’t have generics, but Machine does.
Yeah, sorry, couldn’t resist that one.
Much like the
amazonec2, etc. drivers for
Machine, which allow you to create machine instances with Docker installed and
configured the proper way on an ad-hoc basis and then manage them on those
generic driver does so for ANY machine which you have SSH
access to. You lose a little bit of flexibility in terms of, say, powering off
and on the instance through the provider’s remote API (which the
driver cannot control), but you make up for it in terms of flexibility and
accessibility in terms of bridging Machine with tools it does not directly
account for, e.g. Ansible, or providers which Machine does not natively
Here’s the kicker: All of the options that you use with Machine to configure,
on the created hosts also apply for these hosts you “import” into your Machine
store using the
generic driver. So, bootstrapping and using a Docker Swarm
cluster is becoming easier than ever (you can just use existing machines to run
it if you want to), and so is interacting with the Docker daemon which is
running on those hosts directly. Introspecting the state of your system and
running Docker daemons Secure communication from your client to the remote
daemons using TLS is, of course, also a huge plus, and is something else which
Machine sets up automatically for you.
Let’s take a look at this in action.
The Generic Driver in Action
Note: If you want to follow along at home, you can grab the most recent release candidate from GitHub. Cheers!
Let’s say that I’ve created a server through the DigitalOcean admin interface,
and imported my public key into the instance (so I can SSH in without having to
type a password). That’s cool, but I want to use it with Docker and Docker
Machine, and I don’t have any of that set up and configured right now. On top
of that, I want to make it a master node for a Docker Swarm. That sounds
pretty scary and/or tedious to set up by hand, but Machine with the
driver can automate the process for you quite nicely.
Firstly, we have to create a Swarm token if we don’t have one already (this is used for discovery by the master and its worker nodes):
$ docker run swarm create 181a89a5589fbc7f3be78e09b585d21a
Suppose my instance is at the IP address
22.214.171.124. Since I have SSH
sudo access on the box (which Machine needs in order to work), I can
bootstrap all of the things listed above with just one command:
$ docker-machine create \ -d generic \ --swarm \ --swarm-master \ --swarm-discovery token://181a89a5589fbc7f3be78e09b585d21a \ --generic-ip-address 126.96.36.199 \ gendo
This will create a new Docker Machine host,
gendo, which has Docker (and
Swarm!) configured and ready to rip. We might have had to specify the path to
the SSH key file or name of the user to work as, but in this case the defaults
root for those values served fine.
You can see it in the output of
$ docker-machine ls NAME ACTIVE DRIVER STATE URL SWARM dev * virtualbox Running tcp://192.168.99.124:2376 gendo generic Running tcp://188.8.131.52:2376
Best of all, it is configured as a Swarm master, so you can create other nodes which join the cluster using the same discovery token if you wish. All of this is set up behind the scenes for you based on your desired configuration, so you don’t have to go mucking about with TLS certificates and the like just to play with Swarm. It is automated for you.
You can use the swarm master with:
eval $(docker-machine env --swarm gendo).
$ # To use plain old Docker... $ eval $(docker-machine env gendo) $ docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 0a4bddd2b2eb swarm:latest "/swarm join --addr 52 seconds ago Up 52 seconds 2375/tcp swarm-agent a4ea6691c9b4 swarm:latest "/swarm manage --tls 53 seconds ago Up 53 seconds 2375/tcp, 0.0.0.0:3376->3376/tcp swarm-agent-master $ # Nice, the swarm containers are bootstrapped automatically. $ eval $(docker-machine env --swarm gendo) # Now let's talk to the swarm master $ docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES $ # The Swarm containers are gone! Don't worry, it's just the master only shows them with "docker ps -a". $ docker info Containers: 2 Strategy: spread Filters: affinity, health, constraint, port, dependency Nodes: 1 gendo: 184.108.40.206:2376 └ Containers: 2 └ Reserved CPUs: 0 / 1 └ Reserved Memory: 0 B / 514.5 MiB $ # And now you're cooking with Swarm.
I think this is the basis of a really powerful and flexible method which eventually will be used to bridge the gap between Docker Machine and other tools such as Terraform and Ansible, among other use cases.
I hope that this little teaser preview, makes you want to go try it out ;D
Until next time, stay sassy Internet.