This document provides a summary of a presentation about using Docker volume plugins with OpenStack Cinder block storage. The presentation discusses: 1. The speaker introducing themselves and their background with OpenStack Cinder. 2. An overview of the Docker volume plugin API and how the speaker created a Cinder volume plugin in Golang to provide block storage to Docker containers. 3. A demonstration of deploying a sample web application on a Docker Swarm cluster using the Cinder volume plugin to persist Redis data, showing how storage can be provided to containers across nodes.

1. Consuming Cinder from
Docker
John Griffith
SolidFire/NetApp
August 23, 2016

2. About me
• Contributing to OpenStack a while (longer than some, less than others)
• Have been pretty passionate about core Cinder and things like reference driver
• Worked at a little Storage Startup called SolidFire recently bought by NetApp
• Have an AWESOME job where I get to work on OSS and always try new things
• Can be opinionated and blunt at times… sorry about that
2

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Maybe you showed up because you heard
rumors that I’d talk about Docker?

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OpenStack Cinder -Block Storage as a Service
• Abstraction layer to provide a pool of Block Resources
• Use backend storage from different vendors, don’t have to care of
know what’s actually serving up the blocks
• Scale out… just keep plugging in back-ends
• Scheduler can figure out where to place volumes for you

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It’s like having an infinite number of disks
That you can hot plug in and out of your Instances
Photo Credit: Roger Smith

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Only really need a few things
• Create/Delete
• Attach/Detach
• Snapshot

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Of course there’s more for those that want it
• Replication
• CG’s
• Backups
• Migration
• Imports/Exports
• Transfer ownership
• Extend
• ...
(This is me trying not to be opinionated and blunt… moving on)

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I was told this would be a Docker talk!!

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Yes, I’m going to talk about Docker
• Docker is the best geek bait EVER!!!
• “OpenStack in Containers”
• “Container Orchestration in OpenStack”
• “OpenStack on Kubernetes”

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Unicorns for EVERYONE
• All sorts of interesting ideas and plans on
the horizon
• Let’s bypass some of the hype and just
talk about some cool stuff you can do
today
• Try to remember a little bit of the past
while we’re at it

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History repeats itself in tech
• $NEW_THING is like pets vs cattle
• $NEW_THING needs better networking
• $NEW_THING needs persistent storage
• $NEW_THING is a different development paradigm
• $NEW_THING is about small ephemeral services
echo $NEW_THING
OpenStack
export NEW_THING=Containers

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Just like we heard in OpenStack –Containers need
networking and storage options
• Volume Plugin capability for Docker introduced initially in 1.8
• Continues to mature
• List of Vendors racing to provide a plugin accelerating rapidly
• Nobody wants to be late to the party, especially those that were late to Cinder

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Docker Volume Plugins –General things to know
• Docker provides a simple Volume API
• INCLUDES PROVISIONING!!!!!
• Driver runs as a daemon
• Most common right now are simple UNIX domain sockets
• Runs on same node as the Docker Engine
• json-rpc over http POST
• Works with Swarm, Engine and Compose

14. So I wrote a Cinder Plugin
• Written in Golang
• Focus on JUST Cinder
• Vendor neutral/independent
• Open Source
• Gladly welcome contributors and feedback
• Anticipating/Hoping for Cinder community support
14

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Can’t I already do this?
Yep, you can
Cool stuff out there already
Adoption is the greatest compliment

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Don’t get me wrong
Some of those existing plugins that wrap up Cinder
are pretty cool
Some offer additional benefits
Some might fit your use case better
Some of them you may have already invested in and
have relationships with the contributing vendors
Do your thing, that’s AWESOME
Don’t hate, we’re all in this together

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Brace yourselves, it’s about to get terrifying…
Well… for a few people at least

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These Plugins aren’t under an umbrella
• Docker Plugins are NOT in a Docker repo
• Cinder Docker Plugin isn’t in an OpenStack repo

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Some OpenStack folks just had a stroke
For now: https://github.com/j-griffith/cinder-docker-driver
Licensed under the “unlicense”
Potential for inclusion under OpenStack some day? Or maybe Docker?

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So how does this work
• It’s not “much” different than how we do things with OpenStack/Nova
• Create a volume
• Attach a volume
• It’s all the same stuff we’ve been doing for years, we just change the
consumer
• Cinder really doesn’t care what you’re doing on the other side
• By the way, we’re talking Docker, but it doesn’t have to be Docker either

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I have to give a shout out to Docker on1.12
• Docker 1.12 was a HUGE step forward
• Swarm advancements are my favorite
• I can deploy a Swarm cluster wicked fast
• Swarm in OpenStack or Public Cloud is stupid easy

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Recipe for a tasty Swarm Cluster with persistent data
Start with some Peanut Butter
• Basic OpenStack Cloud
• Compute Networking and Storage
Mix in a bit of Chocolate
• Docker 1.12
Top it off with some frosting
• Cinder Docker Driver

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We’ll use docker-machine with the OpenStack driver –
Because we can, and it works pretty well
(Our OpenStack Cloud)

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We have our ingredients, here’s the basic steps
1. docker-machine to create 3 Nova Instances and setup Docker
2. Create a Swarm Cluster
3. Install , configure and start the cinder-docker-driver
4. Deploy a Swarm service that creates and uses a Cinder Volume

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Create our nodes –use env vars instead of args
We’ll use docker-machine and the built in OpenStack driver for this
There’s a LOT of arguments required to the cli, so let’s start by creating an env file rather
than typing everything in.
export OS_FLAVOR_ID=2export OS_DOMAIN_NAME=$OS_USER_DOMAIN_NAME
export OS_IMAGE_ID=d5c276bc-cb70-42c4-9291-96f40a03a74c
export OS_SSH_USER=ubuntu
export OS_KEYPAIR_NAME=jdg
export OS_PRIVATE_KEY_FILE=$HOME/.ssh/id_rsaexport OS_SSH_USER=ubuntu
export OS_TENANT_ID=$OS_PROJECT_ID

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Create our nodes
This just does our ”nova boot ….” for us, creating the Instances based on env vars
It does a few additional things for us too though
• Install Docker
• Configure and Setup certs for Docker
• Verify Docker is up and running
• Create a node entry in the docker nodes db
➜ docker-machine create –d openstack swarm-1
➜ docker-machine create –d openstack swarm-2
➜ docker-machine create –d openstack swarm-3

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We can view our nodes using docker-machine
➜ docker-machine ls
NAME ACTIVE DRIVER STATE URL SWARM DOCKER
ERRORS
swarm-1 - openstack Running tcp://172.16.140.157:2376 v1.12.0
swarm-2 - openstack Running tcp://172.16.140.159:2376 v1.12.0
swarm-3 - openstack Running tcp://172.16.140.161:2376 v1.12.0

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Set a node up as a Swarm Manager
➜ eval $(docker-machine env swarm-1)
➜ SWARM-1-IP=$(docker-machine ip swarm-1)
➜ docker swarm init --advertise-addr $SWARM-1-IP –listen-addr $SWARM-1-IP:2377
Swarm initialized: current node (5oi3h06yci5mvsau6czcbbxqu) is now a manager.
To add a worker to this swarm, run the following command:
docker swarm join
--token SWMTKN-1-33zfeg2ppr9043o4itdn2cznwn7yuy7na1fqg2aduoemihw93o
-3znh32dbpmb5goc8l1ia286it 172.16.140.157:2377
To add a manager to this swarm, run 'docker swarm join-token manager' and follow the
instructions.

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Set our other two Instances as Workers
➜ eval $(docker-machine env swarm-2)
➜ docker swarm join --token SWMTKN-1-33zfeg2ppr9043o4itdn2cznwn7yuy7na1fqg2aduoemihw93o-
3znh32dbpmb5goc8l1ia286it 172.16.140.157:2377
This node joined a swarm as a worker.
➜ eval $(docker-machine env swarm-3)
➜ docker swarm join --token SWMTKN-1-33zfeg2ppr9043o4itdn2cznwn7yuy7na1fqg2aduoemihw93o-
3znh32dbpmb5goc8l1ia286it 172.16.140.157:2377
This node joined a swarm as a worker.

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That’s it, you now have a Swarm Cluster!!!!

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Now it’s time to install the Cinder Driver
on each Node
• Install the driver
• Copy over a config file
• Start the daemon
• Restart Docker

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You can just use docker-machine from
your laptop…
➜ for each in $(docker-machine ls -q); do; docker-machine ssh $each "curl –sSL
https://raw.githubusercontent.com/j-griffith/cinder-docker-driver/master/install.sh
| sh -" ; done
➜ for each in $(docker-machine ls -q); do; docker-machine scp cdd.config.json
$each:~/config.json; done
➜ for each in $(docker-machine ls -q); do; docker-machine ssh $each "sudo
cinder-docker-driver --config config.json > cdd.log 2>&1 &" ; done
➜ for each in $(docker-machine ls -q); do; docker-machine ssh $each "sudo
Service docker restart" ; done

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About that install….
Config file is just OpenStack Creds
Creating a Service file for the driver has made
it’s way up pretty far on the TODO list
{
"Endpoint": "http://172.16.140.243:5000/v2.0",
"Username": "jdg",
"Password": “ABC123",
"TenantID": "3dce5dd10b414ac1b942aba8ce8558e7“
}

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Now you can do cool things
Let’s build the simple counter application
• Redis container with Cinder Volume
• Web front end to take user input
We’ll run this as a Swarm service, so we can do things
like scale it, drain-nodes and move the containers
uninterrupted.
All while persisting our Redis data

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Create a Docker network first so the Swarm
nodes have a layer to communicate on…
➜ eval $(docker-machine env swarm-1)
➜ docker network create demo-net
Bd45fad9911005ce2ff8e311a2738681d179589d8d06989a136e8020bc5a8155

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Launch our services, start with the Redis
service…
➜ eval $(docker-machine env swarm-1)
➜ docker service create --name redis --network demo-net –-mount
type=volume,src=counter-demo,dst=/data,volume-driver=cinder -p 6379:6379 redis
This will:
• Pull the Redis image if it’s not available
• Get/Create the volume on the Cinder backend
• Attach the Volume to the Swarm node
• Partition, Format and Mount the Volume
• Link the volume to the Redis Containers /data directory
• Start the Redis Container

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You can see the attached volume on the
Swarm Node….
ubuntu@swarm-3:~$ ls /dev/disk/by-path/
ip-10.10.9.1:3260-iscsi-iqn.2010-01.com.solidfire:ayyb.uuid-59e99b3b-c7d6-45c2-924c-
virtio-pci-0000:00:04.0
virtio-pci-0000:00:04.0-part1
Same as we do for Nova Compute nodes… nothing really different except we add the file system

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Now, the web service/frontend…
➜ docker service create --name web --network demonet -p 80:80
jgriffith/jgriffith webbase
This will:
• Connect to our Redis container (regardless of what Swarm node it’s on)
• Expose port 80 to all of the Swarm Nodes (access from any Swarm Node IP)
• Count input/clicks and store them in the Redis DB

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Can’t show you a live demo 
Next best thing…. Movies!!!
1. Create Swarm Cluster and install the Driver on
Nodes
2. Create our Service using a Cinder Volume
3. Demo the Service and fail it over to another Node

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