[infinispan-dev] Maintenance of OpenShift templates

Wed Mar 7 03:11:54 EST 2018

On Tue, Mar 6, 2018 at 5:11 PM Galder Zamarreño <galder at redhat.com> wrote:

> Sebastian Laskawiec <slaskawi at redhat.com> writes:
>
> > Hey Galder,
> >
> > Comments inlined.
> >
> > Thanks,
> > Seb
> >
> > On Fri, Mar 2, 2018 at 11:37 AM Galder Zamarreño <galder at redhat.com>
> > wrote:
> >
> >     Hi,
> >
> >     Looking at [1] and I'm wondering why the templates have to
> >     maintain a
> >     different XML file for OpenShift?
> >
> >     We already ship an XML in the server called `cloud.xml`, that
> >     should
> >     just work. Having a separate XML file in the templates means we're
> >     duplicating the maintainance of XML files.
> >
> >     Also, users can now create caches programmatically. This is by far
> >     the
> >     most common tweak that had to be done to the config. So, I see the
> >     urgency to change XML files less immediate.
> >
> > So just to give you guys a bit more context - the templates were
> > created pretty long time ago when we didn't have admin capabilities in
> > Hot Rod and REST. The main argument for putting the whole
> > configuration into a ConfigMap was to make configuration changes
> > easier for the users. With ConfigMap approach they can log into
> > OpenShift UI, go to Resources -> ConfigMaps and edit everything using
> > UI. That's super convenient for hacking in my opinion. Of course, you
> > don't need to do that at all if you don't want. You can just spin up a
> > new Infinispan cluster using `oc new-app`.
>
> I agree with the usability of the ConfigMap. However, the duplication is
> very annoying. Would it be possible for the ConfigMap to be created on
> the fly out of the cloud.xml that's shipped by Infinispan Server? That
> way we'd still have a ConfigMap without having to duplicate XML.
>

Probably not. This would require special permissions to call Kubernetes API
from the Pod. In other words, I can't think about any other way that would
work in OpenShift Online for the instance.

>
> > There are at least two other ways for changing the configuration that
> > I can think of. The first one is S2I [1][2] (long story short, you
> > need to put your configuration into a git repository and tell
> > OpenShift to build an image based on it). Even though it may seem very
> > convenient, it's OpenShift only solution (and there are no easy (out
> > of the box) options to get this running on raw Kubernetes). I'm not
> > judging whether it's good or bad here, just telling you how it works.
> > The other option would be to tell the users to do exactly the same
> > things we do in our templates themselves. In other words we would
> > remove configuration from the templates and provide a manual for the
> > users how to deal with configuration. I believe this is exactly what
> > Galder is suggesting, right?
>
> What we do in the templates right now to show users how to tweak their
> config is in convoluted.
>
> Ideally, adding their own custom configuration should be just a matter
> of:
>
> 1. Creating a ConfigMap yaml pointing to an XML.
> 2. Ask users to put their XML in a separate file pointed by the ConfigMap.
> 3. Deploy ConfigMap and XML.
> 4. Trigger a new Infinispan redeployment.
>

That would probably need to be a new deployment. Most of the StatefulSet
spec is immutable.

>
> Not sure how doable this is with the current template approach, or we
> could explain how to do this for an already up and running application
> that has Infinispan created out of the default template?
>

I've been thinking about this for a while and this is what I think we
should do:

   1. Wait a couple of weeks and review the community image created by the
   CE Team. See if this is a good fit for us. If it is, I would focus on
   adopting this approach and adjust our templates to handle it.
   2. Whether or not we adopt the CE community work, we could put all
   necessary stuff into cloud.xml or services.xml configuration. We could do
   one step forward and merge them together.
   3. Make sure that dynamically created caches are persisted (this is
   super important!!)
   4. Once #3 is verified we should have a decision whether or not we are
   adopting the CE way. At this point we could document how to use custom
   configuration with a ConfigMap and drop it from the templates.

WDYT? Does this plan makes sense to you?

>
> >
> > Recently we implemented admin commands in the Hot Rod. Assuming that
> > caches created this way are not wiped out during restart (that needs
> > to be checked), we could remove the configuration from the templates
> > and tell the users to create their caches over Hot Rod and REST.
> > However we still need to have a back door for modifying configuration
> > manually since there are some changes that can not be done via admin
> > API.
> >
> > [1] https://github.com/openshift/source-to-image
> > [2]
> >
> https://github.com/jboss-dockerfiles/infinispan/blob/master/server/.s2i/bin/assemble
> >
> >
> >     Sure, there will always be people who modify/tweak things and
> >     that's
> >     fine. We should however show the people how to do that in a way
> >     that
> >     doesn't require us to duplicate our maintanence work.
> >
> > If we think about further maintenance, I believe we should take more
> > things into consideration. During the last planning meeting Tristan
> > mentioned about bringing the project and the product closer together.
> > On the Cloud Enablement side of things there are ongoing experiments
> > to get a community images out.
> >
> > If we decided to take this direction (the CE way), our templates would
> > need to be deprecated or will change drastically. The image will react
> > on different set of variables and configuration options.
> >
> >     Also, if we want to show the users how to use a custom XML file, I
> >     don't
> >     think we should show them how to embedd it in the template as JSON
> >     [2]. It's quite a pain. Instead, the XML should be kept as a
> >     separate
> >     file and the JSON file reference it.
> >
> > I'm still struggling to understand why this is a pain. Could you
> > please explain it a bit more? If you look into the maintenance guide
> > [3], there are only a few steps. For me it takes no longer than 15
> > minutes to do the upgrade. You also mentioned on IRC that this
> > approach is a pain for our users (I believe you mentioned something
> > about Ray). I also can not understand why, could you please explain it
> > a bit more?
> >
> > [3]
> >
> https://github.com/infinispan/infinispan-openshift-templates#maintenance-guide
> >
> >
> >     Cheers,
> >
> >     [1]
> >
> https://github.com/infinispan/infinispan-openshift-templates/pull/16/files
> >
> >     [2]
> >
> https://github.com/infinispan/infinispan-openshift-templates#maintenance-guide
> >
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> >
> >
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