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202 changes: 202 additions & 0 deletions LICENSE.txt
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69 changes: 69 additions & 0 deletions README.md
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# Skuber

Skuber is a Scala client library for [Kubernetes](http://kubernetes.io). It provides a high-level and strongly typed Scala API for remotely managing and reactively monitoring Kubernetes resources (such as Pods, Containers, Services, Replication Controllers etc.) via the Kubernetes API server.

The client supports v1 of the Kubernetes REST API.

## Sample Usage

The code block below illustrates the simple steps required to create a replicated nginx service on a Kubernetes cluster.

The service uses five replicated pods, each running a Docker container of an nginx image (Kubernetes will automatically pull the image if necessary). Each pod publishes the exposed port 80 of its container, on which the nginx service is running.

The service can be accessed from outside the cluster at port 30001 on each node, which Kubernetes proxies to port 80 on the service endpoints (i.e. the pods in which the nginx containers are currently running).

import skuber._
import skuber.json.format._

val nginxSelector = Map("app" -> "nginx")
val nginxContainer = Container("nginx",image="nginx").port(80)
val nginxController= ReplicationController("nginx",nginxContainer,nginxSelector).withReplicas(5)
val nginxService = Service("nginx", nginxSelector, Service.Port(port=80, nodePort=30001))

import scala.concurrent.ExecutionContext.Implicits.global

val k8s = k8sInit

val createOnK8s = for {
rc <- k8s create nginxController
svc <- k8s create nginxService
} yield (rc,svc)

createOnK8s onComplete {
case Success(_) => System.out.println("Successfully created nginx replication controller & service on Kubernetes cluster")
case Failure(ex) => System.err.println("Encountered exception trying to create resources on Kubernetes cluster: " + ex)
}

k8s.close

The code snippet above illustrates only a small part of the Skuber functionality, which covers most of the capabilites of the Kubernetes API - for more examples see the reactive Guestbook example in the examples project, and the tests under client/src/test/scala.

## Features

- Comprehensive Scala case class representations of the Kubernetes types supported by the API server; including Pod, Service, ReplicationController, Nodes, Container, Endpoint, Namespace, Volume, PersistentVolume, Resource, Security, EnvVar, ServiceAccount, LimitRange, Secret, Event and others
- Support for Kubernetes object, list and simple kinds
- Fluent API for building the desired specification ("spec") of a Kubernetes object to be created or updated on the server
- Implicit json formatters for reading and writing the Kubernetes types
- Support for create, get, delete, list, update, and watch operations on Kubernetes types using an asynchronous and type-safe interface that maps each operation to the appropriate Kubernetes RESTful API HTTP requests.
- Watching Kubernetes objects returns Iteratees for reactive processing of events from the cluster
- Client contexts (including connection details and namespace) can be configured by a combination of system properties and a config file format based on the Kubernetes kubeconfig file YAML format

## Build Instructions

The project consists of two sub-projects - the main Skuber client library (under the 'client' directory) and an 'examples' project which currently contains just the reactive Guestbook example.

A sbt build file is provided at the top-level directory, so you can use standard SBT commands to build JARs for both projects or select one project to build.

The reactive guestbook example can be built and run as a fat JAR using the sbt assembly plug-in, which is probably the quickest way to get it up and running.

## Requirements

The client library requires Java 8. The build uses sbt 0.13. A Kubernetes cluster that supports v1.0 of the API is a runtime requirement.

## Status

The coverage of the Kubernetes API functionality by Skuber is extensive, however this is an early ALPHA release with all the caveats that implies.

- Testing has largely used the default configuration, which connects to a Kubernetes cluster via a kubectl proxy running on localhost:8001 and uses the default namespace. Your mileage may vary with other client configurations.
- If some functionality isn't covered by the tests and examples included in this release you should assume it hasn't been tested.
- Documentation is currently sparse to non-existent - in practice a reasonable knowledge of both Kubernetes and Scala will be a prerequisite, from there the Skuber tests and example should help get you up and running.
19 changes: 13 additions & 6 deletions build.sbt
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Expand Up @@ -9,7 +9,6 @@ val commonsIO = "commons-io" % "commons-io" % "2.4"
val playIterateesExtra = "com.typesafe.play.extras" %% "iteratees-extras" % "1.5.0"

// Akka is required by the examples

val akka ="com.typesafe.akka" %% "akka-actor" % "2.4.0"

// Need Java 8 or later as the java.time package is used to represent K8S timestamps
Expand All @@ -23,19 +22,27 @@ lazy val commonSettings = Seq(
scalaVersion := "2.11.7"
)

lazy val skuberSettings = Seq(
name := "skuber-client",
libraryDependencies ++= Seq(playws,playIterateesExtra,snakeYaml,commonsIO,scalaCheck % Test,specs2 % Test).
map(_.exclude("commons-logging","commons-logging"))
)

lazy val examplesSettings = Seq(
name := "skuber-examples",
libraryDependencies += akka
)

lazy val root = (project in file(".")) aggregate(
client,
examples)

lazy val client = (project in file("client")).
settings(commonSettings: _*).
settings(
libraryDependencies ++= Seq(playws,playIterateesExtra,snakeYaml,commonsIO,scalaCheck % Test,specs2 % Test).
map(_.exclude("commons-logging","commons-logging"))
)
settings(skuberSettings: _*)

lazy val examples = (project in file("examples")).
settings(commonSettings: _*).
settings(libraryDependencies += akka).
settings(examplesSettings: _*).
dependsOn(client)

12 changes: 12 additions & 0 deletions client/src/main/scala/skuber/Container.scala
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Expand Up @@ -23,6 +23,18 @@ case class Container(
imagePullPolicy: Container.PullPolicy.Value = Container.PullPolicy.IfNotPresent,
securityContext: Option[Security.Context] = None)
extends Limitable
{
def port(port: Int, prot:Protocol.Value = Protocol.TCP) : Container =
this.copy(ports=Container.Port(containerPort=port, protocol=prot)::this.ports)
def port(p: Container.Port) : Container = this.copy(ports=p::this.ports)
def env(e: (String, String)*) = {
import EnvVar.strToValue
val envVarSeq = e map { case (n,v) => EnvVar(n,v) }
this.copy(env = this.env ++ envVarSeq)
}
def entrypoint(cmd: String*) = this.copy(command=cmd.toList)
}


object Container {

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10 changes: 10 additions & 0 deletions client/src/main/scala/skuber/ReplicationController.scala
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Expand Up @@ -38,6 +38,16 @@ object ReplicationController {
def apply(name: String) : ReplicationController = ReplicationController(metadata=ObjectMeta(name=name))
def apply(name: String, spec: ReplicationController.Spec) : ReplicationController =
ReplicationController(metadata=ObjectMeta(name=name), spec = Some(spec))
def apply(name:String, container: Container, selector: Map[String, String]) : ReplicationController = {
val podSpec=Pod.Spec(containers=List(container))
apply(name, podSpec, selector)
}
def apply(name:String, podSpec: Pod.Spec, selector: Map[String, String]) : ReplicationController = {
val meta=ObjectMeta(name=name, labels = selector)
val templSpec=Pod.Template.Spec(metadata=meta, spec=Some(podSpec))
ReplicationController(metadata=meta, spec=Some(Spec(template=Some(templSpec),selector=Some(selector))))
}

case class Spec(
replicas: Int=1,
selector: Option[Map[String, String]] = None,
Expand Down
9 changes: 8 additions & 1 deletion client/src/main/scala/skuber/Service.scala
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Expand Up @@ -25,8 +25,15 @@ object Service {

def apply(name: String): Service = Service(metadata=ObjectMeta(name=name))
def apply(name: String, spec: Service.Spec) : Service = Service(metadata=ObjectMeta(name=name), spec = Some(spec))
def apply(name: String, selector: Map[String, String], port: Int): Service =
apply(name, selector, Port(port=port))
def apply(name: String, selector: Map[String,String], port: Port): Service = {
val meta=ObjectMeta(name=name,labels=selector)
val serviceType=if (port.nodePort != 0) Type.NodePort else Type.ClusterIP
val spec=Spec(ports=List(port), selector=selector,_type=serviceType)
Service(metadata=meta,spec=Some(spec))
}


object Affinity extends Enumeration {
type Affinity=Value
val ClientIP, None=Value
Expand Down
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