Expose Service

You can determine how to expose your service in the AppConfiguration model via the ports field (under the network accessory). The ports field defines a list of all the Ports you want to expose for the application (and their corresponding listening ports on the container, if they don't match the service ports), so that it can be consumed by other applications.

Unless explicitly defined, each of the ports exposed is by default exposed privately as a ClusterIP type service. You can expose a port publicly by specifying the public field in the Port schema. At the moment, the implementation for publicly access is done via Load Balancer type service backed by cloud providers. Ingress will be supported in a future version of kusion.

For the Port schema reference, please see here for more details.

Prerequisites

Please refer to the prerequisites in the guide for deploying an application.

The example below also requires you to have initialized the project using the kusion workspace create and kusion init command, which will create a workspace and also generate a kcl.mod file under the stack directory.

Managing Workspace Configuration

In the first guide in this series, we introduced a step to initialize a workspace with an empty configuration. The same empty configuration will still work in this guide, no changes are required there.

However, if you (or the platform team) would like to set default values for the services to standardize the behavior of applications in the dev workspace, you can do so by updating the ~/dev.yaml:

modules:
  kusionstack/network@0.1.0: 
    default:
      port: 
        type: alicloud
        labels:
            kusionstack.io/control: "true"
        annotations:
            service.beta.kubernetes.io/alibaba-cloud-loadbalancer-spec: slb.s1.small

The workspace configuration need to be updated with the command:

kusion workspace update dev -f ~/dev.yaml

For a full reference of what can be configured in the workspace level, please see the workspace reference.

Example

simple-service/dev/main.k:

import kam.v1.app_configuration as ac
import kam.v1.workload as wl
import kam.v1.workload.container as c
import network as n

"helloworld": ac.AppConfiguration {
    workload: wl.Service {
        containers: {
            "helloworld": c.Container {
                image = "gcr.io/google-samples/gb-frontend:v4"
                env: {
                    "env1": "VALUE"
                    "env2": "VALUE2"
                }
                resources: {
                    "cpu": "500m"
                    "memory": "512Mi"
                }
                # Configure an HTTP readiness probe
                readinessProbe: p.Probe {
                    probeHandler: p.Http {
                        url: "http://localhost:80"
                    }
                    initialDelaySeconds: 10
                }
            }
        }
        replicas: 2
    }
    accessories: {
        "network": n.Network {
            ports: [
              n.Port {
                  port: 8080
                  targetPort: 80
              }
            ]
        }
    }
}

The code above changes the service port to expose from 80 in the last guide to 8080, but still targeting the container port 80 because that's what the application is listening on.

Applying

Re-run steps in Applying, new service configuration can be applied.

$ kusion apply
 ✔︎  Generating Spec in the Stack dev...                                                                                                                                                                                                     
Stack: dev  ID                                                               Action
* ├─     v1:Namespace:simple-service                                      UnChanged
* ├─     v1:Service:simple-service:simple-service-dev-helloworld-private  Update
* └─     apps/v1:Deployment:simple-service:simple-service-dev-helloworld  UnChanged


? Do you want to apply these diffs? yes
Start applying diffs ...
 SUCCESS  UnChanged v1:Namespace:simple-service, skip                                                                                                                                                                                         
 SUCCESS  Update v1:Service:simple-service:simple-service-dev-helloworld-private success                                                                                                                                                      
 SUCCESS  UnChanged apps/v1:Deployment:simple-service:simple-service-dev-helloworld, skip                                                                                                                                                     
UnChanged apps/v1:Deployment:simple-service:simple-service-dev-helloworld, skip [3/3] ██████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████ 100% | 0s
Apply complete! Resources: 0 created, 1 updated, 0 deleted.

Validation

We can verify the Kubernetes service now has the updated attributes (mapping service port 8080 to container port 80) as defined in the ports configuration:

kubectl get svc -n simple-service -o yaml
...
  spec:
    ...
    ports:
    - name: simple-service-dev-helloworld-private-8080-tcp
      port: 8080
      protocol: TCP
      targetPort: 80
...

Exposing service port 8080:

kubectl port-forward svc/simple-service-dev-helloworld-private -n simple-service 30000:8080

Open browser and visit http://127.0.0.1:30000, the application should be up and running：