OSCONF - Your own Kubernetes controller: not only in Go

OSCONF - Your own Kubernetes controller: not only in Go

• 1.
  @nicolas_frankel Your own Kubernetes OperatorController: Not Only In Go!
• 2.
  @nicolas_frankel • Former developer,team lead, architect, blah-blah • Curious about Kubernetes • Stuck at home Me, myself and I
• 3.
  @nicolas_frankel Hazelcast HAZELCAST IMDG isan operational, in-memory, distributed computing platform that manages data using in-memory storage, and performs parallel execution for breakthrough application speed and scale. HAZELCAST JET is the ultra fast, application embeddable, 3rd generation stream processing engine for low latency batch and stream processing.
• 4.
  @nicolas_frankel “Kubernetes (K8s) isan open-source system for automating deployment, scaling, and management of containerized applications.” Kubernetes
• 5.
  @nicolas_frankel Kubernetes architecture In Kubernetesin Action by Marko Luksa, Fig. 1.9
• 6.
  @nicolas_frankel “The Kubernetes APIserver validates and configures data for the api objects which include pods, services, replication controllers, and others. The API Server services REST operations and provides the frontend to the cluster’s shared state through which all other components interact.” Kubernetes API Server
• 7.
  @nicolas_frankel • Command-line toolthat interacts with the API server • kubectl get pods --v=6 kubectl
• 8.
  @nicolas_frankel “In Kubernetes, controllersare control loops that watch the state of your cluster, then make or request changes where needed. Each controller tries to move the current cluster state closer to the desired state.” Controllers
• 9.
  @nicolas_frankel • Deployment controller •Job controller • etc. Out-of-the-box controllers
• 10.
  @nicolas_frankel • Out-of-the-box controllersrun in the control plane • Custom controllers can run anywhere • As a Pod (or multiple Pods) inside the cluster • As anything outside the cluster Where are controllers located?
• 11.
  @nicolas_frankel “An Operator isan application-specific controller that extends the Kubernetes API to create, configure and manage instances of complex stateful applications on behalf of a Kubernetes user. It builds upon the basic Kubernetes resource and controller concepts, but also includes domain or application-specific knowledge to automate common tasks better managed by computers.” Operator vs. controller
• 12.
  @nicolas_frankel “Defining a CRDobject creates a new custom resource with a name and schema that you specify. The Kubernetes API serves and handles the storage of your custom resource.” Custom Resource Definition
• 13.
  @nicolas_frankel apiVersion: apiextensions.k8s.io/v1beta1 kind: CustomResourceDefinition metadata: name:hazelcasts.hazelcast.com spec: group: hazelcast.com names: kind: Hazelcast listKind: HazelcastList plural: hazelcasts singular: hazelcast scope: Namespaced subresources: status: {} versions: - name: v1alpha1 served: true storage: true Defining a CRD
• 14.
  @nicolas_frankel • To simplify,an operator is just a controller that manages a CRD • If you know how to develop a controller, you know how to develop an operator Operator vs. controller
• 15.
  @nicolas_frankel • Must “talk”to the API server • REST-based • One can create a controller using the shell only The technology stack of controllers
• 16.
  @nicolas_frankel • Kubernetes iswritten in Go • Rewritten from Java • Go is pervasive in the K8s ecosystem Why Go?
• 17.
  @nicolas_frankel varFoo, err :=GetFoo() if err != nil { return err } sliceBar, err := SliceTheBar(varFoo) if err != nil { return err } err := CheckBarSlice(sliceBar) if err != nil { return err } Why not Go?
• 18.
  @nicolas_frankel • Making theswitch to a new language is hard • Learning the syntax • Using it in an idiomatic way • Getting to know the libraries • Getting the right tooling • Getting used to it • Your team already knows X, use it Why X?
• 19.
  @nicolas_frankel You know whereI’m heading to… I know Java
• 20.
  @nicolas_frankel
• 21.
  @nicolas_frankel A word aboutGraalVM • JVM platform • Polyglot • Java, Python, JavaScript, R, Ruby, C • Truffle: • Programming Language implementation helper • Substrate VM: • Create native executables from bytecode
• 22.
  @nicolas_frankel Recap • What areControllers • Controllers vs. operators • No tech stack required • JVM for the win! • With some GraalVM love
• 23.
  @nicolas_frankel • https://blog.frankel.ch/ • @nicolas_frankel •http://bit.ly/jvm-controller Thanks a lot!