# How to 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.

# Preconditions

None

# Steps

# 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

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" your@email.com

# 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

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