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Lab KUDO

Objective

The focus of this lab is to become familar with KUDO. Through this lab you hand craft an operator, create an operator repository and install the operator to your kubernetes cluster.

Prerequisites

  • Running Kubernetes 1.15+ cluster

Create an Operator from Scratch

This is a step-by-step walk through of the creation of an operator using the KUDO CLI to generate the KUDO operator structure.

Create the Core Operator Structure

# create operator folder
mkdir first-operator
cd first-operator
kubectl kudo package new first-operator

This creates the main structure of the operator which can be viewed using the tree command:

$ tree .
.
└── operator
    ├── operator.yaml
    └── params.yaml

::: tip Note Use the -i flag with kubectl kudo package new to be prompted interactively for operator details. :::

Add a Maintainer

kubectl kudo package add maintainer "your name" [email protected]

Add a Task

kubectl kudo package add task

This command uses an interactive prompt to construct the details of the task. Here is an example interaction:

$ kubectl kudo package add task
Task Name: app
✔ Apply
Task Resource: deployment
✗ Add another Resource:

Add a Plan

kubectl kudo package add plan

This command uses an interactive prompt to construct the details of the plan. Here is an example interaction:

$ kubectl kudo package add plan
✔ Plan Name: deploy
✔ serial
Phase 1 name: main
✔ parallel
Step 1 name: everything
✔ app
✗ Add another Task:
✗ Add another Step:
✗ Add another Phase:

Add a Parameter

kubectl kudo package add parameter

This command uses an interactive prompt to construct the details of the parameter. Here is an example interaction:

$ kubectl kudo package add parameter
Parameter Name: replicas
Default Value: 2
Display Name:
Description: Number of replicas that should be run as part of the deployment
✔ false
✗ Add Trigger Plan:

These steps have created the entirety of the first-operator with the exception of the details in the template/deployment.yaml file. To complete this operator execute the following:

cat << EOF > operator/templates/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: {{ .Params.replicas }}
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
        - name: nginx
          image: nginx:1.7.9
          ports:
            - containerPort: 80
EOF

Package a KUDO operator

In order to distribute a KUDO operator the files are packaged together in a compressed tarball. The KUDO CLI provides a mechanism to create this package format while verifying the integrity of the operator.

Package KUDO Operator

rm -rf ~/repo
mkdir -p ~/repo
kubectl kudo package create repository/first-operator/operator/ --destination=~/repo

::: warning Potential Data Loss You may want to check the contents of the ~/repo folder prior to deleting it. :::

The output looks like:

kubectl kudo package create repository/first-operator/operator/ --destination=~/repo
package is valid
Package created: /Users/kensipe/repo/first-operator-0.2.0.tgz

Check to see the operator is built

ls ~/repo
first-operator-0.2.0.tgz

Initialize KUDO in a Cluster

The objective of this lab is to initialize KUDO in a Kubernetes cluster.

Initialize KUDO

kubectl kudo init --wait

This results in:

  1. the deployment of KUDO CRDs
  2. the creation of kudo-system namespace
  3. deployment of the kudo controller

Output of a KUDO init will look like the following:

$ kubectl kudo init
✅ installed crds
✅ installed service accounts and other requirements for controller to run
✅ installed kudo controller

Check to see KUDO Manager is running

The installation of KUDO is verified by confirming that the kudo-controller-manager-0 is in a running status.

$ kubectl get -n kudo-system pod
NAME                        READY   STATUS    RESTARTS   AGE
kudo-controller-manager-0   1/1     Running   0          11m

Host an Operator in a local repository

This lab explains how to host an operator repository on your local system.

Build Local Index File

kubectl kudo repo index ~/repo

Run Repository HTTP Server

cd ~/repo
python -m http.server 80

Add the local repository to KUDO client

kubectl kudo repo add local http://localhost

Set the local repository to default KUDO context

kubectl kudo repo context local

Confirm KUDO context

$ kubectl kudo repo list
NAME     	URL
community	https://kudo-repository.storage.googleapis.com/0.10.0
*local   	http://localhost

::: tip Note The * next to local indicates that it is the default context for the KUDO client. :::

Verify you are using the local repository for an installation

Using the verbose CLI output flag (-v) with KUDO it is possible to trace from where an operator is being installed from.

kubectl kudo install first-operator -v 9

The output should look like:

$ kubectl kudo install first-operator -v 9
repo configs: { name:community, url:https://kudo-repository.storage.googleapis.com/0.10.0 },{ name:local, url:http://localhost }

repository used { name:local, url:http://localhost }
configuration from "/Users/kensipe/.kube/config" finds host https://127.0.0.1:32768
acquiring kudo client
getting package crds
no local operator discovered, looking for http
no http discovered, looking for repository
getting package reader for first-operator, _
repository using: { name:local, url:http://localhost }
attempt to retrieve package from url: http://localhost/first-operator-0.2.0.tgz
first-operator is a repository package from { name:local, url:http://localhost }
operator name: first-operator
operator version: 0.2.0
parameters in use: map[]
operator.kudo.dev/first-operator unchanged
instance first-operator-instance created in namespace default
instance.kudo.dev/v1beta1/first-operator-instance created

You will also see in the terminal running python http.server the following:

127.0.0.1 - - [14/Jan/2020 07:59:24] "GET /index.yaml HTTP/1.1" 200 -
127.0.0.1 - - [14/Jan/2020 07:59:24] "GET /first-operator-0.2.0.tgz HTTP/1.1" 200 -