Kubernetes Client for Scala

A pure functional client for Kubernetes.

Installation

Mill:

ivy"com.goyeau::kubernetes-client:<latest version>"

or

SBT:

"com.goyeau" %% "kubernetes-client" % "<latest version>"

Usage

Client configuration example

import cats.effect.IO
import com.goyeau.kubernetes.client.*
import org.typelevel.log4cats.Logger
import org.typelevel.log4cats.slf4j.Slf4jLogger
import java.io.File
import org.http4s.AuthScheme
import org.http4s.Credentials.Token
import org.http4s.headers.Authorization
import org.http4s.implicits.*
import scala.concurrent.ExecutionContext
import scala.io.Source

implicit val logger: Logger[IO] = Slf4jLogger.getLogger[IO]

val kubernetesClient =
  KubernetesClient[IO](
    KubeConfig.of[IO](
      server = uri"https://k8s.goyeau.com",
      authorization = Option(Authorization(Token(AuthScheme.Bearer, Source.fromFile("/var/run/secrets/kubernetes.io/serviceaccount/token").mkString))),
      caCertFile = Option(new File("/var/run/secrets/kubernetes.io/serviceaccount/ca.crt"))
    )
  )

import cats.effect.IO
import com.goyeau.kubernetes.client.*
import org.typelevel.log4cats.Logger
import org.typelevel.log4cats.slf4j.Slf4jLogger
import java.io.File
import scala.concurrent.ExecutionContext

implicit val logger: Logger[IO] = Slf4jLogger.getLogger[IO]

val kubernetesClient =
  KubernetesClient[IO](KubeConfig.fromFile[IO](new File(s"${System.getProperty("user.home")}/.kube/config")))

Requests

import cats.effect.IO
import com.goyeau.kubernetes.client.*
import org.typelevel.log4cats.Logger
import org.typelevel.log4cats.slf4j.Slf4jLogger
import io.k8s.api.apps.v1.*
import io.k8s.api.core.v1.*
import io.k8s.apimachinery.pkg.api.resource.Quantity
import io.k8s.apimachinery.pkg.apis.meta.v1.ObjectMeta
import java.io.File
import scala.concurrent.ExecutionContext

implicit val logger: Logger[IO] = Slf4jLogger.getLogger[IO]

val kubernetesClient =
  KubernetesClient(KubeConfig.fromFile[IO](new File(s"${System.getProperty("user.home")}/.kube/config")))

val deployment = Deployment(
  metadata = Option(ObjectMeta(name = Option("web-backend"), namespace = Option("my-namespace"))),
  spec = Option(
    DeploymentSpec(
      selector = null,
      strategy = Option(
        DeploymentStrategy(
          `type` = Option("RollingUpdate"),
          rollingUpdate = Option(RollingUpdateDeployment(Option(StringValue("10%")), Option(StringValue("50%"))))
        )
      ),
      template = PodTemplateSpec(
        metadata = Option(
          ObjectMeta(
            labels = Option(Map("app" -> "web", "tier" -> "frontend", "environment" -> "myenv"))
          )
        ),
        spec = Option(
          PodSpec(
            containers = Seq(
              Container(
                name = "nginx",
                image = Option("nginx"),
                resources = Option(
                  ResourceRequirements(
                    Option(Map("cpu" -> Quantity("100m"), "memory" -> Quantity("128Mi"))),
                    Option(Map("cpu" -> Quantity("80m"), "memory" -> Quantity("64Mi")))
                  )
                ),
                volumeMounts = Option(Seq(VolumeMount(name = "nginx-config", mountPath = "/etc/nginx/conf.d"))),
                ports = Option(Seq(ContainerPort(name = Option("http"), containerPort = 8080)))
              )
            ),
            volumes = Option(
              Seq(
                Volume(
                  name = "nginx-config",
                  configMap = Option(ConfigMapVolumeSource(name = Option("nginx-config")))
                )
              )
            )
          )
        )
      )
    )
  )
)

kubernetesClient.use { client =>
  client.deployments.namespace("my-namespace").create(deployment)
}

Development

Pre-requisites

• Java 11 or higher
• Docker

Related projects

• Skuber
• Kubernetes Client for Java

Why Kubernetes Client for Scala?

You might wonder why using this library instead of Skuber for example? Kubernetes Client is a pure functional based on Cats and Http4s.
Another benefit of Kubernetes Client is that (like the Kubernetes Client for Java) it is generating all the payload case classes by just ingesting the swagger api provided by Kubernetes' main repo. That means this project will always remain up to date with the latest Kubernetes API.

Adopters/Projects

• Kerberos-Operator2