A persistent volume could be used for the pod running the DC; if the pod is restarted or if it fails over to another host the persistent volume will be preserved (using one of the shared volume mechanisms in kubernetes/openshift like Ceph/Gluster/Cinder/S3/EBS etc)
On 17 Dec 2014, at 14:42, Brian Stansberry <brian.stansberry@redhat.com> wrote:
On 12/17/14, 3:28 AM, Thomas Diesler wrote:
Folks,
following up on this topic, I worked a little more on WildFly-Camel in
Kubernetes/OpenShift.
These doc pages are targeted for the upcoming 2.1.0 release (01-Feb-2015)
* WildFly-Camel on Docker
<https://github.com/wildfly-extras/wildfly-camel-book/blob/2.1/cloud/docker.md>
* WildFly-Camel on OpenShift
<https://github.com/wildfly-extras/wildfly-camel-book/blob/2.1/cloud/openshift.md>
Great. :)
The setup looks like this
We can now manage these individual wildfly nodes. The domain controller
(DC) is replicated once, the host definition is replicated three times.
Theoretically, this means that there is no single point of failure with
the domain controller any more - kube would respawn the DC on failure
I'm heading on PTO tomorrow so likely won't be able to follow up on this question for a while, but one concern I had with the Kubernetes respawn approach was retaining any changes that had been made to the domain configuration. Unless the domain.xml comes from / is written to some shared storage available to the respawned DC, any changes made will be lost.
Of course, if the DC is only being used for reads, this isn't an issue.
Here some ideas for improvement …
In a kube env we should be able to swap out containers based on some
criteria. It should be possible to define these criteria, emit events
based on them create/remove/replace containers automatically.
Additionally a human should be able to make qualified decisions through
a console and create/remove/replace containers easily.
Much of the needed information is in jmx. Heiko told me that there is a
project that can push events to influx db - something to look at.
If information display contained in jmx in a console has value (e.g in
hawtio) that information must be aggregated and visible for each node.
Currently, we have a round robin service on 8080 which would show a
different hawtio instance on every request - this is nonsense.
I can see a number of high level items:
#1 a thing that aggregates jmx content - possibly multiple MBeanServers
in the DC VM that delegate to respective MBeanServers on other hosts, so
that a management client can pickup the info from one service
#2 look at the existing inluxdb thing and research into how to automate
the replacement of containers
#3 from the usability perspective, there may need to be an openshift
profile in the console(s) because some operations may not make sense in
that env
cheers
—thomas
PS: looking forward to an exiting ride in 2015
On 5 Dec 2014, at 14:36, Thomas Diesler <tdiesler@redhat.com
<mailto:tdiesler@redhat.com>> wrote:
Folks,
I’ve recently been looking at WildFly container deployments on
OpenShift V3. The following setup is documented here
<https://github.com/wildfly-extras/wildfly-camel-book/blob/2.1/cloud/fabric8.md>
<example-rest-design.png>
The example architecture consists of a set of three high available
(HA) servers running REST endpoints.
For server replication and failover we use Kubernetes. Each server
runs in a dedicated Pod that we access via Services.
This approach comes with a number of benefits, which are sufficiently
explained in various OpenShift
<https://blog.openshift.com/openshift-v3-platform-combines-docker-kubernetes-atomic-and-more/>,
Kubernetes
<https://github.com/GoogleCloudPlatform/kubernetes/blob/master/README.md> and
Docker <https://docs.docker.com/> materials, but also with a number of
challenges. Lets look at those in more detail …
In the example above Kubernetes replicates a number of standalone
containers and isolates them in a Pod each with limited access from
the outside world.
* The management interfaces are not accessible
* The management consoles are not visible
With WildFly-Camel we have a Hawt.io
<http://wildflyext.gitbooks.io/wildfly-camel/content/features/hawtio.html> console
that allows us to manage Camel Routes configured or deployed to the
WildFly runtime.
The WildFly console manages aspects of the appserver.
In a more general sense, I was wondering how the WildFly domain model
maps to the Kubernetes runtime environment and how these server
instances are managed and information about them relayed back to the
sysadmin
a) Should these individual wildfly instances somehow be connected to
each other (i.e. notion of domain)?
b) How would an HA singleton service work?
c) What level of management should be exposed to the outside?
d) Should it be possible to modify runtime behaviour of these servers
(i.e. write access to config)?
e) Should deployment be supported at all?
f) How can a server be detected that has gone bad?
g) Should logs be aggregated?
h) Should there be a common management view (i.e. console) for these
servers?
i) etc …
Are these concerns already being addressed for WildFly?
Is there perhaps even an already existing design that I could look at?
Can such an effort be connected to the work that is going on in Fabric8?
cheers
—thomas
PS: it would be area that we @ wildfly-camel were interested to work on
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Brian Stansberry
Senior Principal Software Engineer
JBoss by Red Hat
James
-------
Red Hat
Twitter: @jstrachan
Email:
jstracha@redhat.comBlog:
http://macstrac.blogspot.com/hawtio:
http://hawt.io/fabric8:
http://fabric8.io/Open Source Integration