deployment.yml

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: flask-app
  labels:
    app: flask
spec:
  selector:
    matchLabels:
      app: flask
  template:
    metadata:
      labels:
        app: flask
    spec:
      automountServiceAccountToken: true
      serviceAccountName: <SERVICE_ACCOUNT_NAME>
      containers:
      - name: flask
        env:
        - name: AWS_DEFAULT_REGION
          value: us-east-1
        - name: S3_BUCKET
          value: <NAME_OF_S3_BUCKET>
        image: <IMAGE_REPOSITORY>
        imagePullPolicy: Always
        livenessProbe:
          httpGet:
            path: /
            port: 5000
            scheme: HTTP
        ports:
        - containerPort: 5000
          protocol: TCP
        readinessProbe:
          httpGet:
            path: /test
            port: 5000
            scheme: HTTP
        resources:
          requests:
            cpu: 250m
            memory: 50Mi

flask_s3.py

from os import environ
from flask import Flask
from boto3 import client, resource

app = Flask(__name__)

@app.route('/')
def init():
    try:
        return "app is up"
    except:
        return "environ S3_BUCKET variable not set", 500

@app.route('/test')
def homepage():
    try:
      s3 = resource('s3')
      obj = s3.Object(environ['S3_BUCKET'], 'test')
      return obj.get()['Body'].read().decode('utf-8')
    except:
        return "Error getting param", 403


if __name__ == "__main__":
    app.run(host='0.0.0.0')

sa.yml

---
apiVersion: v1
kind: ServiceAccount
metadata:
  annotations:
    eks.amazonaws.com/role-arn: <ARN_OF_ROLE_FOR_TESTING>
  name: s3-reader

svc.yml

---
apiVersion: v1
kind: Service
metadata:
  labels:
    app: flask
  name: flask-app
spec:
  ports:
  - port: 80
    protocol: TCP
    targetPort: 5000
  selector:
    app: flask
  sessionAffinity: None
  type: ClusterIP