Chapter 14. Exposing services on the application network using YAML

Create a workload that you want to expose on the network, for example:

kubectl create deployment backend --image quay.io/skupper/hello-world-backend --replicas 3

Create a connector resource YAML file:

apiVersion: skupper.io/v2alpha1
kind: Connector
metadata:
  name: backend
  namespace: east
spec:
  routingKey: backend
  selector: app=backend
  port: 8080

This creates a connector in the east site and exposes the backend deployment on the network on port 8080. You can create a listener on a different site using the matching routing key backend to address this service.

To create the connector resource:

kubectl apply -f <filename>

where <filename> is the name of a YAML file that is saved on your local filesystem.

Check the connector status:

kubectl get connector

For example:

NAME    STATUS  ROUTING-KEY     SELECTOR        HOST    PORT    HAS MATCHING LISTENER    MESSAGE
backend Pending backend         app=backend             8080    false   No matching listeners

📌 NOTE By default, the routing key name is set to the name of the connector. If you want to use a custom routing key, set spec.routingKey to your custom value.

Create a listener resource YAML file:

apiVersion: skupper.io/v2alpha1
kind: Listener
metadata:
  name: backend
  namespace: west
spec:
  routingKey: backend
  host: east-backend
  port: 8080

This creates a listener in the west site and matches with the connector that uses the routing key backend. It also creates a service named east-backend exposed on port 8080 in the current namespace.

To create the listener resource:

kubectl apply -f <filename>

where <filename> is the name of a YAML file that is saved on your local filesystem.

Check the listener status:

kubectl get listener

For example:

NAME      ROUTING KEY   PORT   HOST           STATUS   HAS MATCHING CONNECTOR   MESSAGE
backend   backend       8080   east-backend   Ready    true                     OK

📌 NOTE There must be a MATCHING-CONNECTOR for the service to operate.

Create a multi-key listener resource YAML file. For example:

apiVersion: skupper.io/v2alpha1
kind: MultiKeyListener
metadata:
  name: mkl-backend
spec:
  host: mkl-backend
  port: 9092
  strategy:
    weighted:
      routingKeys:
        east-backend: 1
        west-backend: 1

This creates a listener named mkl-backend that exposes a single endpoint on port 9092 and distributes traffic evenly between the east-backend and west-backend routing keys. Each routing key may have multiple connectors; link cost determines which connector is used within each routing key.

To prefer one routing key first and fall back to another, use the priority strategy:

apiVersion: skupper.io/v2alpha1
kind: MultiKeyListener
metadata:
  name: mkl-backend-priority
spec:
  host: mkl-backend-priority
  port: 9095
  strategy:
    priority:
      routingKeys:
        - east-backend-http
        - west-backend-http

To create the multi-key listener resource:

kubectl apply -f <filename>

where <filename> is the name of a YAML file that is saved on your local filesystem.

Check the multi-key listener status:

kubectl get multikeylistener

📌 NOTE If you need to change strategy after you created a multi-key listener, you must delete and recreate the resource. This does not affect changing routing keys or weights.

Create a workload that you want to expose on the network in a non-site namespace, for example:

kubectl create deployment backend --image quay.io/skupper/hello-world-backend --replicas 3 --namespace attached

Create an AttachedConnector resource YAML file in the same namespace:

apiVersion: skupper.io/v2alpha1
kind: AttachedConnector
metadata:
  name: backend
  namespace: attached
spec:
  siteNamespace: skupper
  selector: app=backend
  port: 8080

To create the AttachedConnector resource:

kubectl apply -f <filename>

where <filename> is the name of a YAML file that is saved on your local filesystem.

Create an AttachedConnectorBinding resource YAML file in the site namespace:

apiVersion: skupper.io/v2alpha1
kind: AttachedConnectorBinding
metadata:
  name: backend
  namespace: east
spec:
  connectorNamespace: attached
  routingKey: backend

To create the AttachedConnectorBinding resource:

kubectl apply -f <filename>

where <filename> is the name of a YAML file that is saved on your local filesystem.

Check the AttachedConnectorBinding status from the context of the site namespace:

kubectl get AttachedConnectorBinding

For example:

NAME      ROUTING KEY   CONNECTOR NAMESPACE   STATUS   HAS MATCHING LISTENER
backend   backend       attached              Ready    true