On Feb 11, 2009, at 9:32 AM, Chance Yeoman wrote:
Thank you for information,
My understanding of the plugin-based farming is incomplete as well.
From the Geronimo 2.1 documentation of plugin-based farming, it did
not seem as if node server configuration was checked and updated
upon startup. Is this new to Geronimo 2.2 farming?
I think the plugin based farming is only in 2.2. IIRC the deployment
based farming in 2.1 relies on pushing stuff.
As an alternative to multicast, our configuration could use a
configured admin server approach to node discovery by using a
virtual IP that would route to a master server. Unlike
multicasting, this approach would require configuration external to
Geronimo to remain flexible, like virtual IP routing or DNS
management. While multicast would be a better choice for most
configurations, would it be plausible to include admin server
hostname/IP based node discovery as a configuration option, with
multicast as the default?
That sounds reasonable to me, although I don't know how virtual IP
works.
Since we're talking about a new feature it would be better to move the
discussion to the dev list, and if you would open a jira that would
also help.
Depending on your requirements I can think of a couple of possible
strategies:
1. when a node starts up it request the plugin list from the admin
server. In this case the admin server doesn't track the node members
and if you update a plugin list nodes won't know until they restart.
2. when a node starts up it starts pinging the admin server. The
admin server tracks cluster members similarly to how it does now with
multicast. Changes to plugin lists will be propagated quickly to
running nodes.
I think (2) would be easier to implement as it just replaces the
multicast heartbeat with a more configured one.
Would you be interested in contributing an implementation?
thanks
david jencks
Thank you,
Chance
--
Center for the Application of Information Technologies
----- Original Message -----
From: "David Jencks" <[email protected]>
To: [email protected]
Sent: Tuesday, February 10, 2009 6:32:11 PM GMT -06:00 US/Canada
Central
Subject: Re: Pulling Geronimo Configuration
On Feb 10, 2009, at 1:52 PM, Russell E Glaue wrote:
David Jencks wrote:
On Feb 10, 2009, at 8:09 AM, Chance Yeoman wrote:
Hello All,
I am interested in setting up geronimo installations that can pull
installed plugins and their dependencies exclusively from a
repository
within a master geronimo server. I hope to eventually have an
automated process allowing cluster members to poll a cluster-
specific
geronimo server repository for available, locally uninstalled
plugins. My goal is to be able to more easily manage
geographically
separated cluster members and to quickly add or reinitialize nodes.
I've been having trouble getting started as I receive HTTP 401
responses when installing remote plugins using the admin interface,
even with security turned off on the maven-repo URL. I can list
the
contents of the remote server's repository, but not install
plugins.
That's pretty odd. Can you show the urls being used? You should be
able to check that it's working with a browser.
My question is: Is using the GeronimoAsMavenServlet even the
correct
approach to pull-based configuration? How have others implemented
configuration pulling? Any advice would be greatly appreciated.
If you use a geronimo server as the plugin repo then
GeronimoAsMavenServlet is the correct approach. However, if I were
you
I would give significant consideration to using nexus as the plugin
repo. I think you will have a much easier time integrating this
with a
reasonable build/qa process. In particular, if you build the
plugins
using maven with the car-maven-plugin, you can set the distribution
management repos to be the nexus server and have mvn deploy or mvn
release make the plugin available to the appropriate production
servers.
For satisfying this scenario, how does nexus compare to Archiva, or
Artifactory?
Archiva: http://archiva.apache.org/
Artifactory: http://www.jfrog.org/products.php
I only have experience with nexus and it's worked great for me. I'm
not thrilled with the license. I haven't actually looked but have a
strong impression that it has a lot more/better features than the
older managers.
I hope you are also aware of the plugin-based clustering/farming
support
that may provide the features you need for easy rollout to mutliple
servers. If the existing features there don't exactly match your
needs
please work with us to improve this. For instance IIUC since you
indicate your cluster members are geographically separate the
current
multicast discovery of cluster members may not work for you...
however
changing this to a hardcoded set of servers should be pretty easy.
Or
perhaps you want a hybrid approach where a bunch of multicast-
connected
sub-clusters aggregate to a controller.
I think the desire is to pull down the artifacts, initiated from the
end
geronimo server. So if Geronimo starts up, it can go to the central
Maven repo
and see if it needs to pull down anything for configuration.
The plugin-based farming, from my understanding, does the opposite.
Your understanding is incomplete. With plugin based farming the
actual artifacts are pulled by each cluster member from the
repository.
The central
server pushes out the new artifacts to the end web servers. And
perhaps this
introduces a few possibly undesired circumstances:
1. Centrally pushed out, all servers receive the updates at one
time, not
staggering the updates. Unless you put the servers into multiple
groups so that
each group can receive updates at different times. But that is more
administration.
2. If a server is offline when the push-out occurs, it is out of
date when it
comes back online. Some kind of re-sync has to happen.
If the end geronimo server does a pull on start-up, then it will
always be in
sync at run time. If we know what triggers the pull, an
administrator can
program this into a distributed command (like Rio, or RHN Satellite
command) to
tell the server to sync itself.
Plugin based farming does pretty much this administration step. The
admin server keeps (in a db) plugins, plugin lists, clusters and
plugin-list to plugin and cluster to plugin list associations. It
listens on a multicast address. When a cluster member starts up it
starts a heartbeat ping on that multicast address. When the admin
server recognizes a new cluster member it sends it a list of all the
plugins that are supposed to be installed on it. The cluster member
then installs all the missing plugins on the list.
If you don't like multicast you have to figure out some other way for
the cluster members to find the admin server, such as by telling it.
Then when the admin server fails and you have to move it you need a
way to tell all the cluster members to look elsewhere. I know
multicast is often frowned on but I couldn't think of a plausible
alternative that seemed like it would actually work. If you have any
ideas I'd love to hear them.
If you don't have any need for dynamic plugin administration but are
happy to kill, reinstall, and restart a cluster member whenever the
plugins change then you could do something pretty easily with gshell
to start the server and install a list of plugins on it.... you can
script this very easily so you'd only be shipping a script to the
cluster members.
thanks
david jencks
-RG
thanks
david jencks
Thank you,
Chance
