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Introduction

A plugin for CloudStack to create, manage Kubernetes cluster through CloudStack management server API and UI. This plugin will not make any changes to CloudStack core architecture or schema. It will be disabled by default and can be enabled using global setting value.

It will provide following features,

  • Create a Kubernetes cluster with desired size with different control parameters alongwith multi-master, HA support.

  • Add and manage multiple Kuberneter versions with binaries ISO.

  • Offline installation of Kubernetes and docker binaries on cluster nodes for selected Kubernetes version.

  • Manage cluster, allowing it to be scaled up or down for the number of cluster nodes. Upgrade cluster to newer Kubernetes version.

  • Access kube.config for cluster for accessing Kubernetes dashboard.

  • Delete cluster while removing nodes and Kubernetes services.

References

Pull request:

https://github.com/apache/cloudstack/pull/3680


Use Cases

Plugin will provide Kubernetes integration with CloudStack enabling user to run containerized services using Kubernetes clusters.


Feature Specification

CloudStack Kubernetes Service plugin will add Kubernetes integration in the CloudStack. Plugin will be disabled by default and admin can control its usage using global setting. It will enable run containerized services using Kubernetes clusters.

CKS will use the CoreOS based template for node VMs for running Kubernetes services. For installation of Kubernetes binaries on cluster nodes, a binaries ISO will be used to achieve faster, offline installation. Root admin will be provided with API and UI to upload/register such ISOs for a particular Kubernetes version. A shell script will be added in the codebase to easily create such ISO for a Kubernetes version.

For deployment and setup Kubernetes on cluster nodes, plugin will use Kubernetes tool, kubeadm. kubeadm is the command line tool for easily provisioning a secure Kubernetes cluster on top of physical or cloud servers or virtual machine. Under the hood, master node(s) of the cluster will start a Kubernetes cluster using kubeadm init command with a custom token and worker nodes will be able to join this Kubernetes cluster using kubeadm join command with the same token. More about kubeadm, https://kubernetes.io/docs/reference/setup-tools/kubeadm/kubeadm/

To access Kubernetes dashboard securely, plugin will provide access to kube.config file data which would allow using Kubernetes tools such as kubectl to run proxy locally and thereby accessing dashboard. More about kubectl, https://kubernetes.io/docs/reference/kubectl/overview/

User will be able to create a CloudStack Kubernetes cluster using UI or API. Both UI and API will allow listing these clusters, perform lifecycle tasks over them and perform scaling for the number of nodes in a running cluster.

Minimum supported version of Kubernetes for the plugin will be 1.11

Multi-master, HA support will be available for Kubernetes version 1.16 and above.



Implementation

API

Kubernetes version management related

Kubernetes version management related APIs can only be accessed by root admins

  • addKubernetesSupportedVersion

Add a Kubernetes version that will be supported by CKS with ISO containing Kubernetes binaries for a specific Kubernetes version

Parameters

===========

name = (string) the name of the Kubernetes supported version. (required)

kubernetesversion = (string) the semantic version of the Kubernetes. (required)

url = (string) the URL to where the ISO is currently being hosted. (required)

zoneid = (uuid) the ID of the zone in which Kubernetes supported version will be available.

isoid = (uuid) the ID of the binaries ISO for Kubernetes supported version.

checksum = (boolean) the checksum value of the binaries ISO.

url = (string) the URL of the binaries ISO for Kubernetes supported version.


  • addKubernetesSupportedVersion

Delete a supported Kuberneted version

Parameters

===========

id = (uuid) the ID of the Kubernetes supported version.

deleteiso = (boolean) true if ISO associated with the Kubernetes version to be deleted else false. Default is false.



Kubernetes supported version management related APIs can be accessed by all users

  • listKubernetesSupportedVersions
    List Kubernetes supported versions

    Parameters
    ============
    id = (uuid) the ID of the Kubernetes supported version


Kubernetes cluster management related APIs can be accessed by all users

  • listKubernetesCluster
    List Kubernetes cluster(s)

    Parameters
    ============
    id = (uuid) the ID of the container cluster
    state = (string) state of the container cluster
    name = (string) name of the container cluster


  • createKubernetesCluster
    Creates a cluster of VM's for launching Kubernetes containers.

    Parameters
    ============

    name = (string) name for the container cluster (required)

    description = (string) description for the container cluster

    zoneid = (uuid) availability zone in which container cluster to be launched (required)

    kubernetesversionid = (uuid) the ID of the Kubernetes version with which cluster to be created (required)

    serviceofferingid = (string) the ID of the service offering for the virtual machines in the cluster (required)

    accountid = (uuid) an optional account for the virtual machine.

    projectid = (uuid) deploy cluster for the project

    networkid = (uuid) network in which container cluster is to be launched

    sshkeypairname = (string) name of the ssh key pair used to login to the virtual machines sshkeypair

    masternodes = (integer) number of Kubernetes cluster master nodes when setting up multi-master (default: 1)

    externalloadbalanceripaddress = (string) IP address of an exter load balancer when using multi-master on a shared network

    size = (integer) number of container cluster nodes (required)

    noderootdisksize = (long) root disk size of root disk for each node



  • deleteKubernetesCluster
    Deletes a Kubernetes cluster.

    Parameters
    ============
    id = (uuid) the ID of the container cluster


  • startKubernetesCluster
    Starts a Kubernetes cluster.

    Parameters
    ============
    id = (uuid) the ID of the container cluster


  • stopKubernetesCluster
    Stops a Kubernetes cluster.

    Parameters
    ============
    id = (uuid) the ID of the container cluster


  • getKubernetesClusterConfig
    Returns kube-config file data of a Kubernetes cluster.

    Parameters
    ============
    id = (uuid) the ID of the Kubernetes cluster


  • scaleKubernetesCluster
    Returns kube-config file data of a Kubernetes cluster.

    Parameters
    ============
    id = (uuid) the ID of the container cluster

    size = (integer) the size or worker node count of the Kubernetes cluster

    serviceofferingid = (uuid) the ID of the service offering for the Kubernetes cluster


  • upgradeKubernetesCluster
    Upgrade Kubernetes cluster to given newer version

    Parameters
    ============
    id = (uuid) the ID of the container cluster

    kubernetesversionid = (uuid) the ID of the Kubernetes version

Schema

  1. Table for CKS cluster
    kubernetes_cluster:
    id (bigint, auto_increment),
    uuid (varchar, unique),
    name (varchar, unique),
    description (varchar),
    zone_id (bigint),
    service_offering_id (bigint),
    template_id (bigint),
    network_id (bigint),
    node_count (bigint),
    account_id (bigint),
    domain_id (bigint),
    state (enum/string),
    key_pair (varchar),
    cores (bigint),
    memory (bigint),
    endpoint (varchar),
    created (datetime)
    removed  (datetime)


  2. Table for CKS cluster details
    kubernetes_cluster_details:
    id (bigint, auto_increment),
    cluster_id (bigint),
    name (varchar),
    value (varchar)


  3. Table for CKS cluster VM reference
    kubernetes_cluster_vm_ref:
    id (bigint, auto_increment),
    cluster_id (bigint),
    vm_id (bigint)


  4. Table for CKS Kubernetes version
    kubernetes_supported_version:

    id (bigint, auto_increment),

    uuid (varchar, unique),

    name (varchar),

    kubernetes_verion (varchar),

    name (varchar),

    iso_id (bigint),

    zone_id (bigint),

    created (date)

    removed (date)

UI Changes


List of currently created clusters will be show in UI, in ui/plugins/cks.js.

UI will allow user to add, manage supported Kubernetes versions.

UI will allow user to perform lifecycle tasks on the cluster. It will show a tab based interface to provide cluster details, running VM instances, network rules and steps to access Kubernetes dashboard using kubectl tool.


Testing


Marvin tests cases

    CRUD tests:
        Add cluster, list clusters to confirm addition
        Delete cluster, list clusters to confirm deletion
        Scale cluster, list clusters to confirm scaling
    Cluster management tests:
    Start cluster
    Stop cluster
    Get cluster config



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