Open Stack

On Wed, 1 Oct 2014 09:05:23 PM Fox, Kevin M wrote:
> Has anyone figured out a way of having a floating ip like feature with
> docker so that you can have rabbitmq, mysql, or ceph mon's at fixed ip's
> and be able to migrate them around from physical host to physical host and
> still have them at fixed locations that you can easily put in static config
> files?

This is part of the additional functionality kubernetes adds on top of docker.

kubernetes uses a "proxy" on every host which knows about all the published 
"services".  The services share a port space (ie: every service has to have a 
unique port assigned), and the proxies know where to forward requests to find 
one of the backends for that service.

docker communicates parameters via environment variables and has a few 
standard environment variables that are used for "links" to other containers.  
Kubernetes also uses these link env variables but points them at the proxies 
instead of directly to the other containers.  Since oslo.config can't look up 
environment variables directly (that's something I'd like to add), I have a 
simple shell one-liner that expands environment variables in the relevant 
config files before starting the openstack server.

As a concrete example: I configure a keystone service in my kubernetes config 
and in my static config files I use values like:

   identity_uri = http://$ENV[KEYSTONE_PORT_5000_TCP_ADDR]:
$ENV[KEYSTONE_PORT_5000_TCP_PORT]/v2.0

docker/kubernetes sets those env variables to refer to the proxy on the local 
host and the port number from my service config - this information is static 
for the lifetime of that docker instance.  The proxy will reroute the requests 
dynamically to wherever the actual instances are running right now.

I hope that's enough detail - I encourage you to read the kubernetes docs 
since they have diagrams, etc that will make it much clearer than the above.

 - Gus

> Maybe iptables rules? Maybe adding another bridge? Maybe just disabling the
> docker network stack all together and binding the service to a fixed,
> static address on the host?
> 
> Also, I ran across:
> http://jperrin.github.io/centos/2014/09/25/centos-docker-and-systemd/ and
> it does seem to work. I was able to get openssh-server and keystone to work
> in the same container without needing to write custom start/stop scripts.
> This kind of setup would make a nova compute container much, much easier.
> 
> Thanks,
> Kevin
> ________________________________
> From: Steven Dake [sdake at redhat.com]
> Sent: Wednesday, October 01, 2014 8:04 AM
> To: OpenStack Development Mailing List (not for usage questions)
> Subject: Re: [openstack-dev] [kolla] Kolla Blueprints
> 
> On 09/30/2014 09:55 AM, Chmouel Boudjnah wrote:
> 
> On Tue, Sep 30, 2014 at 6:41 PM, Steven Dake
> <sdake at redhat.com<mailto:sdake at redhat.com>> wrote:
> 
> I've done a first round of prioritization.  I think key things we need
> people to step up for are nova and rabbitmq containers.
> 
> For the developers, please take a moment to pick a specific blueprint to
> work on.  If your already working on something, this hsould help to prevent
> duplicate work :)
> 
> 
> As I understand in the current implementations[1]  the containers are
> configured with a mix of shell scripts using crudini and other shell
> command. Is it the way to configure the containers? and is a deployment
> tool like Ansible (or others) is something that is planned to be used in
> the future?
> 
> Chmouel
> 
> Chmouel,
> 
> I am not really sure what the best solution to configure the containers.  It
> is clear to me the current shell scripts are fragile in nature and do not
> handle container restart properly.  The idea of using Puppet or Ansible as
> a CM tool has been discussed with no resolution.  At the moment, I'm
> satisified with a somewhat hacky solution if we can get the containers
> operational.
> 
> Regards,
> -steve
> 
> 
> 
> 
> [1] from https://github.com/jlabocki/superhappyfunshow/
> 
> 
> 
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-- 
 - Gus