Boto3 NoCredentialsError when trying to pull from DynamoDb on EKS with Fargate

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I have an EKS cluster with a Fargate profile for compute. I've configured the Pod execution role on the Fargate profile with the 2 managed policies.

  1. AmazonEKSFargatePodExecutionRolePolicy
  2. AmazonDynamoDBFullAccess

The code is run as a CronJob, it starts off by pulling a configuration from DynamoDb:

dynamodb = boto3.resource('dynamodb', region_name=region)

table = dynamodb.Table(table_name)

response = table.get_item(
Key = {
  'Id': config_id
})

When the code reaches this point it always exceptions out with:

raise NoCredentialsError()
botocore.exceptions.NoCredentialsError: Unable to locate credentials

I know I can pass the AWS credentials straight in when I initialise the boto3 client but I don't want to do that for security reasons.

I had originally tested the code using an EC2 instance in an auto-scaling group for compute instead of Fargate, which worked.

How do I resolve this error?

amazon-eks aws-fargate kubernetes amazon-web-services python
1 Answers

Following all 3 steps in this guide addressed the issue.

https://docs.aws.amazon.com/eks/latest/userguide/iam-roles-for-service-accounts.html

The problem lay with the service account that was executing the code in my pod.

You need to attach a role to the service account itself. In my implementation I created a new service account, in theory I could have a separate service account with separate permissions per pod.

apiVersion: v1
kind: ServiceAccount
metadata:
  name: your-custom-service-account
  namespace: default
  annotations:
    eks.amazonaws.com/role-arn: arn:aws:iam::12345678910:role/CustomServiceAccountRole
    eks.amazonaws.com/sts-regional-endpoints: 'true'

and then make sure that account is the service account associated with the pod.

spec:
  serviceAccountName: your-custom-service-account

If you don't specify a service account for your pod then it defaults to the 'default' service account that is present in the cluster.

user_118483910
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