Grant IAM users access to Kubernetes with a ConfigMap - Amazon EKS
Add IAM principalsApply the aws-auth   ConfigMap to your cluster

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Grant IAM users access to Kubernetes with a ConfigMap

Important

The aws-auth ConfigMap is deprecated. The recommended method to manage access to Kubernetes APIs is Access Entries.

Access to your cluster using IAM principals is enabled by the AWS IAM Authenticator for Kubernetes, which runs on the Amazon EKS control plane. The authenticator gets its configuration information from the aws-auth ConfigMap. For all aws-auth ConfigMap settings, see Full Configuration Format on GitHub.

Add IAM principals to your Amazon EKS cluster

When you create an Amazon EKS cluster, the IAM principal that creates the cluster is automatically granted system:masters permissions in the cluster's role-based access control (RBAC) configuration in the Amazon EKS control plane. This principal doesn't appear in any visible configuration, so make sure to keep track of which principal originally created the cluster. To grant additional IAM principals the ability to interact with your cluster, edit the aws-auth ConfigMap within Kubernetes and create a Kubernetes rolebinding or clusterrolebinding with the name of a group that you specify in the aws-auth ConfigMap.

Note

For more information about Kubernetes role-based access control (RBAC) configuration, see Using RBAC Authorization in the Kubernetes documentation.

To add an IAM principal to an Amazon EKS cluster

  1. Determine which credentials kubectl is using to access your cluster. On your computer, you can see which credentials kubectl uses with the following command. Replace ~/.kube/config with the path to your kubeconfig file if you don't use the default path.

    cat ~/.kube/config

    An example output is as follows.

    [...]
contexts:
- context:
    cluster: my-cluster.region-code.eksctl.io
    user: admin@my-cluster.region-code.eksctl.io
  name: admin@my-cluster.region-code.eksctl.io
current-context: admin@my-cluster.region-code.eksctl.io
[...]

    In the previous example output, the credentials for a user named admin are configured for a cluster named my-cluster. If this is the user that created the cluster, then it already has access to your cluster. If it's not the user that created the cluster, then you need to complete the remaining steps to enable cluster access for other IAM principals. IAM best practices recommend that you grant permissions to roles instead of users. You can see which other principals currently have access to your cluster with the following command:

    kubectl describe -n kube-system configmap/aws-auth

    An example output is as follows.

    Name:         aws-auth
Namespace:    kube-system
Labels:       <none>
Annotations:  <none>

Data
====
mapRoles:
----
- groups:
  - system:bootstrappers
  - system:nodes
  rolearn: arn:aws:iam::111122223333:role/my-node-role
  username: system:node:{{EC2PrivateDNSName}}


BinaryData
====

Events:  <none>

    The previous example is a default aws-auth ConfigMap. Only the node instance role has access to the cluster.

  2. Make sure that you have existing Kubernetes roles and rolebindings or clusterroles and clusterrolebindings that you can map IAM principals to. For more information about these resources, see Using RBAC Authorization in the Kubernetes documentation.

    1. View your existing Kubernetes roles or clusterroles. Roles are scoped to a namespace, but clusterroles are scoped to the cluster. 

      kubectl get roles -A

      kubectl get clusterroles

    2. View the details of any role or clusterrole returned in the previous output and confirm that it has the permissions (rules) that you want your IAM principals to have in your cluster.

      Replace role-name with a role name returned in the output from the previous command. Replace kube-system with the namespace of the role.

      kubectl describe role role-name -n kube-system

      Replace cluster-role-name with a clusterrole name returned in the output from the previous command.

      kubectl describe clusterrole cluster-role-name

    3. View your existing Kubernetes rolebindings or clusterrolebindings. Rolebindings are scoped to a namespace, but clusterrolebindings are scoped to the cluster.

      kubectl get rolebindings -A

      kubectl get clusterrolebindings

    4. View the details of any rolebinding or clusterrolebinding and confirm that it has a role or clusterrole from the previous step listed as a roleRef and a group name listed for subjects.

      Replace role-binding-name with a rolebinding name returned in the output from the previous command. Replace kube-system with the namespace of the rolebinding.

      kubectl describe rolebinding role-binding-name -n kube-system

      An example output is as follows.

      apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: eks-console-dashboard-restricted-access-role-binding
  namespace: default
subjects:
- kind: Group
  name: eks-console-dashboard-restricted-access-group
  apiGroup: rbac.authorization.k8s.io
roleRef:
  kind: Role
  name: eks-console-dashboard-restricted-access-role
  apiGroup: rbac.authorization.k8s.io

      Replace cluster-role-binding-name with a clusterrolebinding name returned in the output from the previous command.

      kubectl describe clusterrolebinding cluster-role-binding-name

      An example output is as follows.

      apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: eks-console-dashboard-full-access-binding
subjects:
- kind: Group
  name: eks-console-dashboard-full-access-group
  apiGroup: rbac.authorization.k8s.io
roleRef:
  kind: ClusterRole
  name: eks-console-dashboard-full-access-clusterrole
  apiGroup: rbac.authorization.k8s.io

  3. Edit the aws-auth ConfigMap. You can use a tool such as eksctl to update the ConfigMap or you can update it manually by editing it.

    Important

    We recommend using eksctl, or another tool, to edit the ConfigMap. For information about other tools you can use, see Use tools to make changes to the aws-authConfigMap in the Amazon EKS best practices guides. An improperly formatted aws-auth ConfigMap can cause you to lose access to your cluster.

    eksctl
    Prerequisite

    Version 0.190.0 or later of the eksctl command line tool installed on your device or AWS CloudShell. To install or update eksctl, see Installation in the eksctl documentation.

    1. View the current mappings in the ConfigMap. Replace my-cluster with the name of your cluster. Replace region-code with the AWS Region that your cluster is in.

      eksctl get iamidentitymapping --cluster my-cluster --region=region-code

      An example output is as follows.

      ARN                                                                                             USERNAME                                GROUPS                          ACCOUNT
arn:aws:iam::111122223333:role/eksctl-my-cluster-my-nodegroup-NodeInstanceRole-1XLS7754U3ZPA    system:node:{{EC2PrivateDNSName}}       system:bootstrappers,system:nodes

    2. Add a mapping for a role. Replace my-role with your role name. Replace eks-console-dashboard-full-access-group with the name of the group specified in your Kubernetes RoleBinding or ClusterRoleBinding object. Replace 111122223333 with your account ID. You can replace admin with any name you choose.

      eksctl create iamidentitymapping --cluster my-cluster --region=region-code \
    --arn arn:aws:iam::111122223333:role/my-role --username admin --group eks-console-dashboard-full-access-group \
    --no-duplicate-arns
      Important

      The role ARN can't include a path such as role/my-team/developers/my-role. The format of the ARN must be arn:aws:iam::111122223333:role/my-role. In this example, my-team/developers/ needs to be removed.

      An example output is as follows.

      [...]
2022-05-09 14:51:20 [ℹ]  adding identity "arn:aws:iam::111122223333:role/my-role" to auth ConfigMap

    3. Add a mapping for a user. IAM best practices recommend that you grant permissions to roles instead of users. Replace my-user with your user name. Replace eks-console-dashboard-restricted-access-group with the name of the group specified in your Kubernetes RoleBinding or ClusterRoleBinding object. Replace 111122223333 with your account ID. You can replace my-user with any name you choose.

      eksctl create iamidentitymapping --cluster my-cluster --region=region-code \
    --arn arn:aws:iam::111122223333:user/my-user --username my-user --group eks-console-dashboard-restricted-access-group \
    --no-duplicate-arns

      An example output is as follows.

      [...]
2022-05-09 14:53:48 [ℹ]  adding identity "arn:aws:iam::111122223333:user/my-user" to auth ConfigMap

    4. View the mappings in the ConfigMap again.

      eksctl get iamidentitymapping --cluster my-cluster --region=region-code

      An example output is as follows.

      ARN                                                                                             USERNAME                                GROUPS                                  ACCOUNT
arn:aws:iam::111122223333:role/eksctl-my-cluster-my-nodegroup-NodeInstanceRole-1XLS7754U3ZPA    system:node:{{EC2PrivateDNSName}}       system:bootstrappers,system:nodes
arn:aws:iam::111122223333:role/admin                                                            my-role                                 eks-console-dashboard-full-access-group
arn:aws:iam::111122223333:user/my-user                                                          my-user                                 eks-console-dashboard-restricted-access-group
    Edit ConfigMap manually

    1. Open the ConfigMap for editing.

      kubectl edit -n kube-system configmap/aws-auth
      Note

      If you receive an error stating "Error from server (NotFound): configmaps "aws-auth" not found", then use the procedure in Apply the aws-auth   ConfigMap to your cluster to apply the stock ConfigMap.

    2. Add your IAM principals to the ConfigMap. An IAM group isn't an IAM principal, so it can't be added to the ConfigMap.

      • To add an IAM role (for example, for federated users): Add the role details to the mapRoles section of the ConfigMap, under data. Add this section if it does not already exist in the file. Each entry supports the following parameters:

        • rolearn: The ARN of the IAM role to add. This value can't include a path. For example, you can't specify an ARN such as arn:aws:iam::111122223333:role/my-team/developers/role-name. The ARN needs to be arn:aws:iam::111122223333:role/role-name instead.

        • username: The user name within Kubernetes to map to the IAM role.

        • groups: The group or list of Kubernetes groups to map the role to. The group can be a default group, or a group specified in a clusterrolebinding or rolebinding. For more information, see Default roles and role bindings in the Kubernetes documentation.

      • To add an IAM user: IAM best practices recommend that you grant permissions to roles instead of users. Add the user details to the mapUsers section of the ConfigMap, under data. Add this section if it does not already exist in the file. Each entry supports the following parameters:

        • userarn: The ARN of the IAM user to add.

        • username: The user name within Kubernetes to map to the IAM user.

        • groups: The group, or list of Kubernetes groups to map the user to. The group can be a default group, or a group specified in a clusterrolebinding or rolebinding. For more information, see Default roles and role bindings in the Kubernetes documentation.

      For example, the following YAML block contains:

      • A mapRoles section that maps the IAM node instance to Kubernetes groups so that nodes can register themselves with the cluster and the my-console-viewer-role IAM role that is mapped to a Kubernetes group that can view all Kubernetes resources for all clusters. For a list of the IAM and Kubernetes group permissions required for the my-console-viewer-role IAM role, see Required permissions.

      • A mapUsers section that maps the admin IAM user from the default AWS account to the system:masters Kubernetes group and the my-user user from a different AWS account that is mapped to a Kubernetes group that can view Kubernetes resources for a specific namespace. For a list of the IAM and Kubernetes group permissions required for the my-user IAM user, see Required permissions.

      Add or remove lines as necessary and replace all example values with your own values.

      # Please edit the object below. Lines beginning with a '#' will be ignored,
# and an empty file will abort the edit. If an error occurs while saving this file will be
# reopened with the relevant failures.
#
apiVersion: v1
data:
  mapRoles: |
    - groups:
      - system:bootstrappers
      - system:nodes
      rolearn: arn:aws:iam::111122223333:role/my-role
      username: system:node:{{EC2PrivateDNSName}}
    - groups:
      - eks-console-dashboard-full-access-group
      rolearn: arn:aws:iam::111122223333:role/my-console-viewer-role
      username: my-console-viewer-role
  mapUsers: |
    - groups:
      - system:masters
      userarn: arn:aws:iam::111122223333:user/admin
      username: admin
    - groups:
      - eks-console-dashboard-restricted-access-group      
      userarn: arn:aws:iam::444455556666:user/my-user
      username: my-user

    3. Save the file and exit your text editor.

Apply the aws-auth   ConfigMap to your cluster

The aws-auth ConfigMap is automatically created and applied to your cluster when you create a managed node group or when you create a node group using eksctl. It is initially created to allow nodes to join your cluster, but you also use this ConfigMap to add role-based access control (RBAC) access to IAM principals. If you've launched self-managed nodes and haven't applied the aws-auth ConfigMap to your cluster, you can do so with the following procedure.

To apply the aws-authConfigMap to your cluster

  1. Check to see if you've already applied the aws-auth ConfigMap.

    kubectl describe configmap -n kube-system aws-auth

    If you receive an error stating "Error from server (NotFound): configmaps "aws-auth" not found", then proceed with the following steps to apply the stock ConfigMap.

  2. Download, edit, and apply the AWS authenticator configuration map.

    1. Download the configuration map.

      curl -O https://s3.us-west-2.amazonaws.com/amazon-eks/cloudformation/2020-10-29/aws-auth-cm.yaml

    2. In the aws-auth-cm.yaml file, set the rolearn to the Amazon Resource Name (ARN) of the IAM role associated with your nodes. You can do this with a text editor, or by replacing my-node-instance-role and running the following command:

      sed -i.bak -e 's|<ARN of instance role (not instance profile)>|my-node-instance-role|' aws-auth-cm.yaml

      Don't modify any other lines in this file.

      Important

      The role ARN can't include a path such as role/my-team/developers/my-role. The format of the ARN must be arn:aws:iam::111122223333:role/my-role. In this example, my-team/developers/ needs to be removed.

      You can inspect the AWS CloudFormation stack outputs for your node groups and look for the following values:

      • InstanceRoleARN – For node groups that were created with eksctl

      • NodeInstanceRole – For node groups that were created with Amazon EKS vended AWS CloudFormation templates in the AWS Management Console

    3. Apply the configuration. This command may take a few minutes to finish.

      kubectl apply -f aws-auth-cm.yaml
      Note

      If you receive any authorization or resource type errors, see Unauthorized or access denied (kubectl) in the troubleshooting topic.

  3. Watch the status of your nodes and wait for them to reach the Ready status.

    kubectl get nodes --watch

    Enter Ctrl+C to return to a shell prompt.