Hi Pavithra,

Since POD IPs change, you have to rely on DNS records. To have a fixed DNS name like  kamailio.kamalio-service.namespace.svc.cluster.local for a pod you will have to use StatefullSet, so the pod DNS name doesn't change. Also you have to use Services and set it to ClusterIP: none, it will turn your pods to headless services and no load balancing is involved. and from my understanding you will be able to reach each POD directly through the DNS name.
https://kubernetes.io/docs/concepts/services-networking/service/

and don't forget to set  your /etc/resolv.conf with the kubedns IP address.

Abdirahman



On Wed, 26 Aug 2020 at 12:45, Pavithra Mohanraja <pavimohan3004@gmail.com> wrote:
Hi Abdirahman,

Do you mean , if I set clusterIP as None, then kubedns server will be pointing to pod ip so that kubedns/coredns will use pod ip for pod communication instead of service IP.


Is my understanding correct? From your explanation.

If this is the case, pod ip will be changing whenever I launch the pods . How that can be resolved.

Could you kindly helo me with this?


Thanks,
Pavithra

On Wed, Aug 26, 2020, 9:26 PM Abdirahman A. Osman <abdirahman.osm@gmail.com> wrote:
David,

Assuming those are pod ips. Using services doesn’t work since the dns name will resolve to a k8s service ip and no the actual pod running the service.

If you set   clusterIP: None in the services, you will get POD IP.

Abdirahman



On Wed, 26 Aug 2020 at 10:48, Pavithra Mohanraja <pavimohan3004@gmail.com> wrote:
Hi, 
Thanks for the answers.
@David has got my question.

I have a seperate dns server running in my pcscf pod . So in my /etc/resolv.conf file , I would be configuring 
nameserver <pcscf pod ip>
in all other cscf pods as well for communication.



My question here is how to change the dns server pointing to cluster ip so that my domain name for IMS will be pointing to coredns itself. It will restrict me from using pod IP since it changes everytime.


@David, can you please tell me the last two lines briefly. I did not get it.how you configured . You mean to say still you are using pod Ip.


On Wed, Aug 26, 2020, 8:02 PM David Villasmil <david.villasmil.work@gmail.com> wrote:
I’ve been trying to figure this out as well.
I haven’t yet found a way of publishing to kube-dns the pod IP of the running service. 

I.e.: 
kamailio.whatever.local on ip 10.0.0.1
Rtpengine.whatever.local on ip 10.0.0.2
Appserver.whatever.local on 10.0.0.3

Assuming those are pod ips. Using services doesn’t work since the dns name will resolve to a k8s service ip and no the actual pod running the service.

Assigning IPs hardcoded doesn’t work either since it might change if the docker changes pod. I can have multiple modes on which a service can run, but only one service (kamailio, rtpengine, appserver, etc) will run on a given pod.

On Wed, 26 Aug 2020 at 15:18, Abdirahman A. Osman <abdirahman.osm@gmail.com> wrote:
Hi

Pavithra








You can use the kubedns/CoreDNS of the kubernetes cluster to resolve Internal DNS records of the pods.To assign DNS records for each POD you have to deploy a service and set the ClusterIP: none. and the dns record will be something like kamailio.kamalio-service.platform.svc.cluster.local
which is the podname.servicename.namespace.svc.cluster.local

In the resolve.conf you will put the kubeDNS/CoreDNS IP as the nameserver.  You can set this in the kubernetes manifest file

      dnsPolicy: "None"
      dnsConfig:
        nameservers:
          - 10.34.0.1 (

kubeDNS/CoreDNS )




Abdirahman



On Tue, 25 Aug 2020 at 15:34, Sergey Safarov <s.safarov@gmail.com> wrote:
I am not k8s developer.
So cannot provide detailed instructions. Just my point of view.

You can look
https://kubernetes.io/docs/concepts/extend-kubernetes/operator/
https://www.magalix.com/blog/creating-custom-kubernetes-operators



On Tue, Aug 25, 2020 at 7:41 PM Pavithra Mohanraja <pavimohan3004@gmail.com> wrote:
Hi,

It would be helpful if you could elaborate what has to be done for kubernetes pods when you mention sip ingress


Thanks,


Pavithra




On Tue, Aug 25, 2020, 9:32 PM Sergey Safarov <s.safarov@gmail.com> wrote:
Lot of issues with static IP in Kubernetes.

Looks as need deploy "sip ingress" like "HTTP/HTTPS ingress" and then route calls to pods.


On Tue, Aug 25, 2020 at 4:40 PM Pavithra Mohanraja <pavimohan3004@gmail.com> wrote:
Hi,

I am configuring kamailio IMS as kubernetes pods .
so each component will be configured as separate pod .
In order to establish a connection between pods , I am configuring bind9 dns server in pcscf pod itself. Communication is happening via Pod IP address.

Is there any possibility to have the communication using cluster IP . If anybody is aware of kubernetes, Please help me in this regard.

I have my /etc/resolv.conf file in pods with
nameserver <clusterIP>
search <cluster-dns-domain-name>

Please help.


Thanks,
Pavithra


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