aws eks and aws sso RBAC authentication problem

Question

I have created a fresh AWS SSO (used internal IDP as identity source, so no use of Active Directory).
I am able to login to AWS CLI, AWS GUI, but unable to perform any kubectl ops.

error: You must be logged in to the server (Unauthorized)

This has something to do with the RBAC I think as I am able to get EKS token via aws eks get-token.

➜ cat ~/.aws/config

[profile team-sso-admin]
sso_start_url=https://team.awsapps.com/start
sso_region=us-west-2
sso_account_id=1111111111
sso_role_name=AdministratorAccess
region=us-west-2
credential_process = aws-vault exec team-sso-admin --json


➜ aws-vault exec team-sso-admin --debug -- zsh --login
➜ env | grep AWS
AWS_VAULT_PROMPT=pass
AWS_VAULT_BACKEND=pass
AWS_VAULT=team-sso-admin
AWS_DEFAULT_REGION=us-west-2
AWS_REGION=us-west-2
AWS_ACCESS_KEY_ID=xxx
AWS_SECRET_ACCESS_KEY=xxx
AWS_SESSION_TOKEN=xxx
AWS_SECURITY_TOKEN=yyy
AWS_SESSION_EXPIRATION=2021-01-11T05:55:51Z
AWS_SDK_LOAD_CONFIG=1

➜ aws sts get-caller-identity --output yaml 

Account: '111111111111'
Arn: arn:aws:sts::111111111111:assumed-role/AWSReservedSSO_AdministratorAccess_6c71da2aa3076dfb/TestUser
UserId: XXX:TestUser

➜ aws eks get-token --cluster-name team-shared-eks --role arn:aws:iam::111111111111:role/aws-reserved/sso.amazonaws.com/us-west-2/AWSReservedSSO_AdministratorAccess_67d1da2aa3076dfb

{"kind": "ExecCredential", "apiVersion": "client.authentication.k8s.io/v1alpha1", "spec": {}, "status": {"expirationTimestamp": "2021-01-11T02:49:11Z", "token": "xxx"}}

kubeconfig

config

- name: arn:aws:eks:us-west-2:111111111111:cluster/team-shared-eks
  user:
    exec:
      apiVersion: client.authentication.k8s.io/v1alpha1
      args:
      - --region
      - us-west-2
      - eks
      - get-token
      - --cluster-name
      - team-shared-eks
      - --role
      - arn:aws:iam::111111111111:role/aws-reserved/sso.amazonaws.com/us-west-2/AWSReservedSSO_AdministratorAccess_67d1da2aa3076dfb
      command: aws

aws-auth

mapRoles: |
    - "groups":
      - "system:bootstrappers"
      - "system:nodes"
      "rolearn": "arn:aws:iam::111111111111:role/team-shared-eks20210110051740674200000009"
      "username": "system:node:{{EC2PrivateDNSName}}"
    - "groups":
      - "system:master"
      "rolearn": "arn:aws:iam::111111111111:role/team-saml-devops"
      "username": "team-devops"
    - "groups":
      - "system:master"
      "rolearn": "arn:aws:iam::111111111111:role/aws-reserved/sso.amazonaws.com/us-west-2/AWSReservedSSO_AdministratorAccess_67d1da2aa3076dfb"
      "username": "team-sso-devops"

clusterrole binding for team-sso-devops user:

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  creationTimestamp: "2021-01-11T01:37:51Z"
  name: team:sso:devops
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
- apiGroup: rbac.authorization.k8s.io
  kind: User
  name: team-sso-devops
  namespace: default

user_5285732 · Answer

Option #1 - Try removing aws-reserved/sso.amazonaws.com/ from the role_arn

Option #2 - Use aws-iam-authenticator, the official docs provide a thorough example of how to use SSO and kubectl (kubeconfig)

user_13388602 · Answer

client voted another post as an answer, but didn't post the methodology used. For others who may run into this, I', posting what I got to work under the same scenario:

Following tips from this blog:

use AWS console or a similar method to verify the role and get it's arn
modify the supplied arn, trimming out excess path information. In my case I had to remove aws-reserved/sso.amazonaws.com/us-west-2/ from the arn. The goal is to make the arn "read" like a traditional role arn ex: arn:aws:iam::123456789012:role/RoleName
finally, update the aws-auth map roles to use this new arn along with modifying the username to contain the session name, like so:

- "groups":
  - "system:masters"
  "rolearn": "arn:aws:iam::123456789012:role/AWSReservedSSO_AWSAdministratorAccess_randomdigits"
  "username": "AWSAdministratorAccess:{{SessionName}}"

Reminder that this mapRoles entry is in addition to the existing roles and not to delete the bootstrapper entry.

I hope this helps others!

user_18024929 · Answer

as @Meir mentioned, no need to update the kube config,

update configmap aws-auth with the following: mapRoles: |
- "groups":
  - "system:masters" "rolearn": "arn:aws:iam::{{AWS_ACCOUNT}}:role/{{AWSSSO_ROLE}}" "username": "admin:{{SessionName}}"
using temporary AWS Key, Secret & Session Token in env

and you should ready to go.

aws eks and aws sso RBAC authentication problem

3 Answers