I have something like this:
POD-1
|
-------------------------
?|? ?|? ?|?
service-1 service-2 service-3How do I communicate from a server inside a pod, to other servers in pods behind services?
The pods on the other namespace in the same cluster can be reached with just the svc-name.namespace-name
SVC Name: foo
Namespace Name: bar
eg: foo.bar
You need to have services for the pod that you want to access. You can just use internal endpoints of the corresponding services of the pod.
As example let's think there is a mysql pod and service corresponding to it as mysql-svc of type ClusterIP exposing port 3306 as below.
apiVersion: v1
kind: Service
metadata:
name: mysql-svc
spec:
ports:
- name: db-port
protocol: "TCP"
port: 3306
targetPort: 3306
selector:
app: mysqlAnd there is a separate pod of python application which uses that mysql. yo can access that mysql server inside pod using mysql://mysql-svc:3306/dbName which is the internal endpoint of mysql-svc
And if your pods are in two different namespaces (mysql in dev namespace and python app in qa namespace) you can use mysql-svc.dev.svc.cluster.local instead.
If you have another service with pods, you can simply access by using the cluster internal DNS:
For service foo in namespace bar the url is foo.bar.svc.cluster.local. The last part cluster.local can change based on how you deployed the cluster. kops lets you specify different values for it.
When communicating within the same namespace, you don't even need bar you can just do http://foo/ or foo:port with different protocols (like mongo/rabbit/postgrest etc)
If you want to communicate internally within cluster without exposing to internet HTTP/HTTPS i would suggest you to deploy an nginx pod with nodeport and then provide your config in this nginx pod to route your request based on paths for each service. Refer: https://kubernetes.io/docs/concepts/services-networking/connect-applications-service/#exposing-the-service
To access from internet refer https://kubernetes.io/docs/concepts/services-networking/ingress/
Alternatively you could just run each service on different nodeport as explained in https://kubernetes.io/docs/tasks/access-application-cluster/service-access-application-cluster/#creating-a-service-for-an-application-running-in-two-pods