k8s-kotlin-dsl

Introduction: Kotlin DSL for Kubernetes configs
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Kotlin DSL for Kubernetes and Openshift Container Platform on top of fabric8 models.

screencast

k8s-kotlin-dsl package can be found on jcenter. Simply add following lines to your build.gradle:

repositories {
    jcenter()
} 

dependencies {
    compile("com.fkorotkov:kubernetes-dsl:${kubernetes_dsl_version}")
}

Using with kubernetes-client

Let's check out how to create an Ingress via fabric8 client. Don't forget to add a dependency on io.fabric8:kubernetes-client:${kubernetes_client_version}.

import com.fkorotkov.kubernetes.*
import io.fabric8.kubernetes.api.model.IntOrString
import io.fabric8.kubernetes.client.DefaultKubernetesClient


fun main(args: Array<String>) {
  val client = DefaultKubernetesClient().inNamespace("default")
  client.extensions().ingresses().createOrReplace(
    newIngress {
      metadata {
        name = "example-ingress"
      }
      spec {
        backend {
          serviceName = "example-service"
          servicePort = IntOrString(8080)
        }
      }
    }
  )
}

Apply modifications

By leveraging awesomeness of Kotlin it becomes super easy to have a base service template that every microservice is created from:

val baseService = defaultServiceTemplate()
baseService.apply {
  metadata {
    name = "foo"
  }
}

Complete Deployment example

Here is an example of BaseDeployment that defines a deployment with one replica and mounts a secret that can be used by the service.

import io.fabric8.kubernetes.api.model.IntOrString
import io.fabric8.kubernetes.api.model.extensions.Deployment

class BaseDeployment : Deployment {
  constructor(serviceName: String) {
    metadata {
      name = "$serviceName-service-deployment"
      labels = mapOf(
        "app" to serviceName,
        "tier" to "backend"
      )
    }
    spec {
      replicas = 1
      template {
        metadata {
          labels = mapOf(
            "app" to serviceName,
            "tier" to "backend"
          )
        }
        spec {
          containers = listOf(
            newContainer {
              name = "$serviceName-service"
              image = "gcr.io/fkorotkov/$serviceName-service:latest"
              volumeMounts = listOf(
                newVolumeMount {
                  name = "gcp-credentials"
                  mountPath = "/etc/credentials"
                  readOnly = true
                }
              )
              env = listOf(
                newEnvVar {
                  name = "GOOGLE_APPLICATION_CREDENTIALS"
                  value = "/etc/credentials/service-account-credentials.json"
                }
              )
              ports = listOf(
                newContainerPort {
                  containerPort = 8080
                }
              )
              livenessProbe {
                httpGet {
                  path = "/healthz"
                  port = IntOrString(8080)
                }
                periodSeconds = 60
              }
              readinessProbe {
                httpGet {
                  path = "/healthz"
                  port = IntOrString(8080)
                }
                initialDelaySeconds = 10
                periodSeconds = 60
              }
            }
          )
          volumes = listOf(
            newVolume {
              name = "gcp-credentials"
              secret {
                secretName = "gcp-credentials"
              }
            }
          )
        }
      }
    }
  }
}

Contribution

Check CONTRIBUTING.md

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