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Re: Kubernetes endpoints



I've went through Kubernetes documentation and according to Endpoints I've found only this:

* http://kubernetes.io/docs/user-guide/services/

and there is nothing about any logic inside Endpoints / Services which can check if particular endpoint is up and running.

If there can be any simple solution to our problem - we will be amazed!

David Strejc
t: +420734270131

On Wed, Apr 6, 2016 at 2:02 PM, Ben Parees <bparees redhat com> wrote:


On Wed, Apr 6, 2016 at 5:26 AM, David Strejc <david strejc gmail com> wrote:
Our whole team have agreed on following solution:

* We will install nearly same service as ha-proxy router in Open Shift is.

* We will have ha proxy in docker container inside Open Shift on each node
  this will serve as connection point from our applications - we will create service out
  of this HA Proxy dockers

* In case of failure Kubernetes will know about issue and we can use readiness for
  this purpose inside so we will have HA Proxy in front of our infrastructure of MariaDBs

​I guess it sounds like something that could work, but I suspect there might be other ways to communicate endpoint state to the service definition that don't require this extra hop.  Adding Ben Bennett from the team that owns routing.


 

Do we have to use the same system for GlusterFS? 

Use case:

We got glusterfs on each openshift node and they serve as storage for data. We got
Endpoints inside our template and it points to GlusterFS according to Open Shift
documentation for GlusterFS. 

If one node fails - Kubernetes will reschedule all containers on different node, but
what about GlusterFS - will there still be requests to failed node from our apps? 

Due to Kubernetes documentation it chooses Endpoints at random from all endpoints
specified. Does this apply also to GlusterFS plugin? If so wee need to setup HAProxy
also for GlusterFS storage.

Does this make a little bit sense or are we completely wrong with our design? 

I can send design scheme if it will help. 

Many thanks for your help and time.


On Tue, Apr 5, 2016 at 6:28 PM, David Strejc <david strejc gmail com> wrote:
And what about GlusterFS - does Open Shift driver support checking if GlusterFS endpoint is up and running?




On Tue, Apr 5, 2016 at 5:54 PM, Ben Parees <bparees redhat com> wrote:


On Tue, Apr 5, 2016 at 11:26 AM, Tomáš Kukrál <tom 6shore net> wrote:
Hi,
is it really possible to attach Endpoint?

I think readiness probes are limited to containers and thus is can not
solve David's problem because mysql servers are running outside of
OpenShift.


​sorry, didn't realize it's an external service, my advice would not apply if that is the case.

 
tom



On 04-05 09:04, Ben Parees wrote:
> On Tue, Apr 5, 2016 at 3:59 AM, David Strejc <david strejc gmail com> wrote:
>
> > Dear all,
> >
> > my use case is as follows:
> >
> > I got MariaDB galera cluster on each node I got Open Shift installed on
> > (they are bare metals).
> >
> > I've created endpoints such as this:
> >
> > - apiVersion: v1
> >   kind: Endpoints
> >   metadata:
> >     name: mysql
> >   subsets:
> >    - addresses:
> >      - ip: 10.3.0.1
> >      ports:
> >      - port: 3306
> >    - addresses:
> >      - ip: 10.3.1.1
> >      ports:
> >      - port: 3306
> >    - addresses:
> >      - ip: 10.3.2.1
> >      ports:
> >      - port: 3306
> >
> > And I got service which points to this endpoint.
> >
> > My question is - Kubernetes doesn't have any kind of "HA proxy mode" so it
> > can tell that any of nodes behind Endpoint is failing? So lets say I got
> > 10.3.0.1 mysql service stopped and kubernetes round robins connection to
> > this host so every third request on my webapp is failing?
> >
> > This is what I've experienced in my setup.
> >
> > Am I doing something wrong? Or is this a standard behaviour so I have to
> > deploy HA Proxy in between the endpoints and my MySQL database cluster?
> >
>
> ​this what readiness checks are for.  If a container fails its readiness
> check, the endpoint will be removed from the list so it does not serve
> requests:
>
> https://docs.openshift.org/latest/dev_guide/application_health.html#container-health-checks-using-probes
>
> ​
>
>
>
> >
> > Many thanks for advice.
> >
> > David Strejc
> > t: +420734270131
> > e: david strejc gmail com
> >
> > _______________________________________________
> > users mailing list
> > users lists openshift redhat com
> > http://lists.openshift.redhat.com/openshiftmm/listinfo/users
> >
> >
>
>
> --
> Ben Parees | OpenShift

> _______________________________________________
> users mailing list
> users lists openshift redhat com
> http://lists.openshift.redhat.com/openshiftmm/listinfo/users


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