Using DynamoDB

The first step in this process is to re-configure the carts service to use a DynamoDB table that has already been created for us. The application loads most of its confirmation from a ConfigMap, lets take look at it:

~$kubectl -n carts get -o yaml cm carts

apiVersion: v1

data:

  AWS_ACCESS_KEY_ID: key

  AWS_SECRET_ACCESS_KEY: secret

  CARTS_DYNAMODB_CREATETABLE: true

  CARTS_DYNAMODB_ENDPOINT: http://carts-dynamodb:8000

  CARTS_DYNAMODB_TABLENAME: Items

kind: ConfigMap

metadata:

  name: carts

  namespace: carts

The following kustomization overwrites the ConfigMap, removing the DynamoDB endpoint configuration which tells the SDK to default to the real DynamoDB service instead of our test Pod. We've also provided it with the name of the DynamoDB table thats been created already for us which is being pulled from the environment variable CARTS_DYNAMODB_TABLENAME.

Kustomize Patch

~/environment/eks-workshop/modules/security/irsa/dynamo/kustomization.yaml

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
bases:
- ../../../../base-application/carts
configMapGenerator:
- name: carts
  namespace: carts
  env: config.properties
  behavior: replace
  options:
    disableNameSuffixHash: true
resources:
- nlb.yaml

ConfigMap/carts

apiVersion: v1
data:
  CARTS_DYNAMODB_TABLENAME: eks-workshop-carts
kind: ConfigMap
metadata:
  name: carts
  namespace: carts

Diff

 apiVersion: v1
 data:
-  AWS_ACCESS_KEY_ID: key
-  AWS_SECRET_ACCESS_KEY: secret
-  CARTS_DYNAMODB_CREATETABLE: "true"
-  CARTS_DYNAMODB_ENDPOINT: http://carts-dynamodb:8000
-  CARTS_DYNAMODB_TABLENAME: Items
+  CARTS_DYNAMODB_TABLENAME: eks-workshop-carts
 kind: ConfigMap
 metadata:
   name: carts
   namespace: carts

Let's check the value of CARTS_DYNAMODB_TABLENAME then run Kustomize to use the real DynamoDB service:

~$echo $CARTS_DYNAMODB_TABLENAME

eks-workshop-carts

~$kubectl apply -k ~/environment/eks-workshop/modules/security/irsa/dynamo

This will overwrite our ConfigMap with new values:

~$kubectl get -n carts cm carts -o yaml

apiVersion: v1

data:

  CARTS_DYNAMODB_TABLENAME: eks-workshop-carts

kind: ConfigMap

metadata:

  labels:

    app: carts

  name: carts

  namespace: carts

Now we need to recycle all the carts Pods to pick up our new ConfigMap contents:

~$kubectl rollout restart -n carts deployment/carts

deployment.apps/carts restarted

~$kubectl rollout status -n carts deployment/carts

Let us try to access our application using the browser. A LoadBalancer type service named ui-nlb is provisioned in the ui namespace from which the application's UI can be accessed.

~$kubectl get service -n ui ui-nlb -o jsonpath='{.status.loadBalancer.ingress[*].hostname}{"\n"}'

k8s-ui-uinlb-647e781087-6717c5049aa96bd9.elb.us-west-2.amazonaws.com

So now our application should be using DynamoDB right? Load it up in the browser using the output of the above command and navigate to the shopping cart:

http://k8s-ui-uinlb-647e781087-6717c5049aa96bd9.elb.us-west-2.amazonaws.com/cart

The shopping cart page is not accessible! What's gone wrong?