Exercise_5.01

Assignment

This exercise doesn't rely on previous exercises. You may again choose whichever technologies you want for the implementation.

This exercise is difficult!

We need a DummySite resource that can be used to create an HTML page from any URL.

1. Create a "DummySite" resource that has a string property called "website_url".
2. Create a controller that receives a created "DummySite" object from the API
3. Have the controller create all of the resources that are required for the functionality.

Refer to https://kubernetes.io/docs/reference/kubernetes-api/ and https://kubernetes.io/docs/reference/using-api/api-concepts/ for more information on Kubernetes API, and https://kubernetes.io/docs/reference/using-api/client-libraries/ for information about client libraries.

You may also take inspiration from the material example apps: js, go. Note that the JavaScript app does not quite utilize the features of Kubernetes Client, but it calls the REST API directly.

Test that creating a DummySite resource with website_url "https://example.com/" creates a copy of the website. > With a more complex website your "copy" does not need to be a complete one. Eg. in https://en.wikipedia.org/wiki/Kubernetes the CSS styles can be broken:

The controller doesn't have to work perfectly in all circumstances. The following workflow should succeed:

1. apply role, account and binding.
2. apply deployment.
3. apply DummySite

Solution

Binaries

Dummysite

• The Dummysite app is a Dockerised shell script that curls a URL that is stored in a WEBSITE_URL environment variable. The container is built from nginx base image and serves the website on port 80. Source code can be found here.
• Image was pushed to Docker Hub repo viksil/dummysite:latest.

Controller

• The Controller app was written in JavaScript. It takes in WEBSITE_URL environment variable from a DummySite resource manifest and creates deployment, service and ingress for it. The website is forwarded on port 80 and accessible on loadbalancer port of the cluster (localhost port 3055 in this case). Source code can be found here.
• Image was pushed to Docker Hub repo viksil/dummysite_controller:latest.
• Deleting the controller or an existing DummySite does not remove Service and Ingress respources - this could be improved in later versions of the app.

Manifests

CustomResourceDefinition

apiVersion: apiextensions.k8s.io/v1
kind: CustomResourceDefinition
metadata:
  name: dummysites.stable.dwk
spec:
  group: stable.dwk
  scope: Namespaced
  names:
    kind: DummySite
    plural: dummysites
    singular: dummysite
    shortNames:
    - dmms
  versions:
    - name: v1
      served: true
      storage: true
      schema:
        openAPIV3Schema:
          type: object
          properties:
            spec:
              type: object
              properties:
                website_url:
                  type: string
      additionalPrinterColumns:
        - name: WEBSITE_URL
          type: string
          description: The URL of the web page
          jsonPath: .spec.website_url

ServiceAccount

apiVersion: v1
kind: ServiceAccount
metadata:
  name: dummysite-controller-account

Deployment

apiVersion: apps/v1
kind: Deployment
metadata:
  name: dummysite-controller-dep
spec:
  replicas: 1
  selector:
    matchLabels:
      app: dummysite-controller
  template:
    metadata:
      labels:
        app: dummysite-controller
    spec:
      serviceAccountName: dummysite-controller-account
      containers:
        - name: dummysite-controller
          image: viksil/dummysite_controller:latest
          imagePullPolicy: Always

Clusterrole

kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: dummysite-controller-role
rules:
#  probably can be pruned down, not all of the below are strictly necessary
- apiGroups: [""]
  resources: ["pods"]
  verbs: ["get", "list", "watch", "create", "delete"]
- apiGroups: [""]
  resources: ["services"]
  verbs: ["get", "list", "watch", "create", "delete"]
- apiGroups: ["apps"]
  resources: ["deployments"]
  verbs: ["get", "list", "watch", "create", "delete"]
- apiGroups: ["networking.k8s.io"]
  resources: ["ingresses"]
  verbs: ["get", "list", "watch", "create", "delete"]
- apiGroups: ["stable.dwk"]
  resources: ["dummysites"]
  verbs: ["get", "list", "watch", "create", "delete"]

ClusterRoleBinding

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: dummysite-rolebinding
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: dummysite-controller-role
subjects:
- kind: ServiceAccount
  name: dummysite-controller-account
  namespace: default

Example DummySite

apiVersion: stable.dwk/v1
kind: DummySite
metadata:
  name: example-dummysite
spec:
  website_url: https://example.com/

Kubernetes DummySite

apiVersion: "stable.dwk/v1"
kind: DummySite
metadata:
  name: kubernetes-dummysite
spec:
  website_url: https://en.wikipedia.org/wiki/Kubernetes

Commands

Frontend