What will happen to the minions if the kubernetes master node dies ?

[Thomas Privat]

Hi All,

Im running a Kubernetes Cluster with one master node and three minions and Im wondering what will happen to the services and pods on the minions if the master node dies.

Are the services and pods continue running in current state ?

Is it a typical setup that the master node doesnt run services and pods Im creating in the Kubernetes cluster (except of the kubernetes management pods) ?

If yes, is this the reason why "kubectl get nodes" shows the status "SchedulingDisabled" for the master node ?

What is the usual way to run a three node etcd cluster in kubernetes, should we add a http load balancer in front of the etcd nodes to have one ip-address for etcd ?

Or is it possible to configure the three ip addresse from the etcd nodes at the kubernetes minions ?

Is the master node a "stateless" node when etcd is running on stand alone nodes ?

Or in other words, if the master node dies and I start a new one with the old ip-address and the old etcd cluster, will this be a full replacement for the broken node ?

Cheers, Thomas

 

[Rodrigo Campos]

On Tue, Jul 05, 2016 at 01:07:54PM -0700, Thomas Privat wrote:
> Hi All,
>
> Im running a Kubernetes Cluster with one master node and three minions and
> Im wondering what will happen to the services and pods on the minions if
> the master node dies.
> Are the services and pods continue running in current state ?

Yes

> Is it a typical setup that the master node doesnt run services and pods Im
> creating in the Kubernetes cluster (except of the kubernetes management
> pods) ?

I think so, kube-up does that on AWS and I think it generally does that on other
providers. But not sure

> If yes, is this the reason why "kubectl get nodes" shows the status
> "SchedulingDisabled" for the master node ?
>
> What is the usual way to run a three node etcd cluster in kubernetes,
> should we add a http load balancer in front of the etcd nodes to have one
> ip-address for etcd ?
> Or is it possible to configure the three ip addresse from the etcd nodes at
> the kubernetes minions ?

At the minions? Why do you want to do that? Sorry, don't follow



Thanks a lot,
Rodrigo

[Thomas Privat]

Hi Rodrigo,

Thank you for your answers.

>At the minions? Why do you want to do that? Sorry, don't follow

I followed the coreos kuberentes installation. The minions are connected to etcd as well as the master node,
here the flannel config for the nodes:

/etc/flannel/options.env

FLANNELD_IFACE=${ADVERTISE_IP}
FLANNELD_ETCD_ENDPOINTS=${ETCD_ENDPOINTS}

Thats why I asked how the nodes should communicate with a three node etcd cluster.


Cheers, Thomas

[Rodrigo Campos]

On Wed, Jul 06, 2016 at 01:11:08AM -0700, Thomas Privat wrote:
> Hi Rodrigo,
>
> Thank you for your answers.
>
> >At the minions? Why do you want to do that? Sorry, don't follow
>
> I followed the coreos kuberentes installation. The minions are connected to
> etcd as well as the master node,

Ohh, sorry, don't know about that setup :-/

Hope somebody else can help you :). Although just playing around might help to
understand how it works and what happens on different scenarios (just simulate
and understand them, if not too hard :))

[Paul mb]

i Dont understand to well but if you are running a google cloud container, it already comes with the load balancer and kubernetes, so im not sure why would u install coreos,

[Thomas Privat]

Hi !

Im running CoreOS on Bare Metal servers, thats why :-)

Thomas