4. Writing the deployment scripts

Python Flask ApplicationNodeJs Express Application

Python Flask App Deployment Script

4.1. Create a Deployment

Create a deploy.yaml file. In terminal, run the following command:
```
touch deploy.yaml
```

Open the deploy.yaml file in your favourite code editor.

Set the API version to v1 and the kind to Deployment.
```
apiVersion: apps/v1
kind: Deployment
```

Define the metadata for the deployment.

metadata:
  name: sample-app
  labels:
    app: flask

Define the spec for the deployment. Add the container image name as a value for the image: key.

spec:
  replicas: 1
  selector:
    matchLabels:
      app: flask
  template:
    metadata:
      labels:
        app: flask
    spec:
      containers:
      - name: sample-app
        image: <username>/sample-app:v1.0
        ports:
        - containerPort: 8080

Your deploy.yaml file should look something like this:

deploy.yaml

apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2
kind: Deployment
metadata:
  name: sample-app
  labels:
    app: flask
spec:
  replicas: 1
  selector:
    matchLabels:
      app: flask
  template:
    metadata:
      labels:
        app: flask
    spec:
      containers:
      - name: sample-app
        image: <username>/sample-app:v1.0
        ports:
        - containerPort: 8080

Save the file.

4.2. Create a Service

Create a service.yaml file. In terminal, run the following command:
```
touch service.yaml
```

Open the service.yaml file in your favourite code editor.

Set the API version to v1 and the kind to Service.
```
apiVersion: v1
kind: Service
```
Define the metadata for the deployment.
```
metadata:
  name: my-flask-app-service
```

Define the spec for the deployment.

spec:
  selector:
    app: flask
  ports:
  - protocol: TCP
    port: 8080
    targetPort: 8080
    nodePort: 32200
  type: NodePort

Your service.yaml file should look something like this:

service.yaml

apiVersion: v1
kind: Service
metadata:
  name: my-flask-app-service
spec:
  selector:
    app: flask
  ports:
  - protocol: TCP
    port: 8080
    targetPort: 8080
    nodePort: 32200
  type: NodePort

Save the file.

NodeJs Express App Deployment Script

4.1. Create a Deployment

Create a deploy.yaml file. In terminal, run the following command:
```
touch deploy.yaml
```

Open the deploy.yaml file in your favourite code editor.

Set the API version to v1 and the kind to Deployment.
```
apiVersion: apps/v1
kind: Deployment
```

Define the metadata for the deployment.

metadata:
  name: sample-app
  labels:
    app: express

Define the spec for the deployment. Add the container image name as a value for the image: key.

spec:
  replicas: 1
  selector:
    matchLabels:
      app: express
  template:
    metadata:
      labels:
        app: express
    spec:
      containers:
      - name: sample-app
        image: <username>/sample-app:v1.0
        ports:
        - containerPort: 3000

Your deploy.yaml file should look something like this:

deploy.yaml

apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2
kind: Deployment
metadata:
  name: sample-app
  labels:
    app: express
spec:
  replicas: 1
  selector:
    matchLabels:
      app: express
  template:
    metadata:
      labels:
        app: express
    spec:
      containers:
      - name: sample-app
        image: <username>/sample-app:v1.0
        ports:
        - containerPort: 3000

Save the file.

4.2. Create a Service

Create a service.yaml file. In terminal, run the following command:
```
touch service.yaml
```

Open the service.yaml file in your favourite code editor.

Set the API version to v1 and the kind to Service.
```
apiVersion: v1
kind: Service
```

Define the metadata for the deployment.

metadata:
  name: my-express-app-service

Define the spec for the deployment.

spec:
  selector:
    app: express
  ports:
  - protocol: TCP
    port: 80
    targetPort: 3000
    nodePort: 32201
  type: NodePort

Your service.yaml file should look something like this:

service.yaml

apiVersion: v1
kind: Service
metadata:
  name: my-express-app-service
spec:
  selector:
    app: express
  ports:
  - protocol: TCP
    port: 80
    targetPort: 3000
    nodePort: 32201
  type: NodePort

Save the file.

Learning Materials

Yaml Checker provides a quick and easy way to validate YAML
Learn more about Kubernetes Deployments
Learn more about Kubernetes Service
Learn more about Kubernetes Pods