Amazon EKS troubleshooting

This chapter covers some common errors that you may see while using Amazon EKS and how to work around them.

Insufficient capacity

If you receive the following error while attempting to create an Amazon EKS cluster, then one of the Availability Zones you specified does not have sufficient capacity to support a cluster.

Cannot create cluster 'example-cluster' because region-1d, the targeted Availability Zone, does not currently have sufficient capacity to support the cluster. Retry and choose from these Availability Zones: region-1a, region-1b, region-1c

Retry creating your cluster with subnets in your cluster VPC that are hosted in the Availability Zones returned by this error message.

Nodes fail to join cluster

There are a few common reasons that prevent nodes from joining the cluster:

• The aws-auth-cm.yaml file does not have the correct IAM role ARN for your nodes. Ensure that the node IAM role ARN (not the instance profile ARN) is specified in your aws-auth-cm.yaml file. For more information, see Launching self-managed Amazon Linux nodes.

• The ClusterName in your node AWS CloudFormation template does not exactly match the name of the cluster you want your nodes to join. Passing an incorrect value to this field results in an incorrect configuration of the node's /var/lib/kubelet/kubeconfig file, and the nodes will not join the cluster.

• The node is not tagged as being owned by the cluster. Your nodes must have the following tag applied to them, where <cluster-name> is replaced with the name of your cluster.

  Key	Value
  kubernetes.io/cluster/<cluster-name>	owned

• The nodes may not be able to access the cluster using a public IP address. Ensure that nodes deployed in public subnets are assigned a public IP address. If not, you can associate an Elastic IP address to a node after it's launched. For more information, see Associating an Elastic IP address with a running instance or network interface. If the public subnet is not set to automatically assign public IP addresses to instances deployed to it, then we recommend enabling that setting. For more information, see Modifying the public IPv4 addressing attribute for your subnet. If the node is deployed to a private subnet, then the subnet must have a route to a NAT gateway that has a public IP address assigned to it.

• The STS endpoint for the Region that you're deploying the nodes to is not enabled for your account. To enable the region, see Activating and deactivating AWS STS in an AWS Region.

• The worker node does not have a private DNS entry, resulting in the kubelet log containing a node "" not found error. Ensure that the VPC where the worker node is created has values set for domain-name and domain-name-servers as Options in a DHCP options set. The default values are domain-name:<region>.compute.internal and domain-name-servers:AmazonProvidedDNS. For more information, see DHCP options sets in the Amazon VPC User Guide.

Unauthorized or access denied (kubectl)

If you receive one of the following errors while running kubectl commands, then your kubectl is not configured properly for Amazon EKS or the IAM user or role credentials that you are using do not map to a Kubernetes RBAC user with sufficient permissions in your Amazon EKS cluster.

• could not get token: AccessDenied: Access denied

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

• error: the server doesn't have a resource type "svc"

This could be because the cluster was created with one set of AWS credentials (from an IAM user or role), and kubectl is using a different set of credentials.

When an Amazon EKS cluster is created, the IAM entity (user or role) that creates the cluster is added to the Kubernetes RBAC authorization table as the administrator (with system:masters permissions). Initially, only that IAM user can make calls to the Kubernetes API server using kubectl . For more information, see Managing users or IAM roles for your cluster. If you use the console to create the cluster, you must ensure that the same IAM user credentials are in the AWS SDK credential chain when you are running kubectl commands on your cluster.

If you install and configure the AWS CLI, you can configure the IAM credentials for your user. For more information, see Configuring the AWS CLI in the AWS Command Line Interface User Guide.

If you assumed a role to create the Amazon EKS cluster, you must ensure that kubectl is configured to assume the same role. Use the following command to update your kubeconfig file to use an IAM role. For more information, see Create a kubeconfig for Amazon EKS.

aws eks update-kubeconfig \
    --region <region-code> \
    --name <cluster_name> \
    --role-arn arn:aws:iam::<aws_account_id>:role/<role_name>

To map an IAM user to a Kubernetes RBAC user, see Managing users or IAM roles for your cluster.

aws-iam-authenticator Not found

If you receive the error "aws-iam-authenticator": executable file not found in $PATH, then your kubectl is not configured for Amazon EKS. For more information, see Installing aws-iam-authenticator.

Note

The aws-iam-authenticator is not required if you have the AWS CLI version 1.16.156 or higher installed.

hostname doesn't match

Your system's Python version must be 2.7.9 or later. Otherwise, you receive hostname doesn't match errors with AWS CLI calls to Amazon EKS. For more information, see What are "hostname doesn't match" errors? in the Python Requests FAQ.

getsockopt: no route to host

Docker runs in the 172.17.0.0/16 CIDR range in Amazon EKS clusters. We recommend that your cluster's VPC subnets do not overlap this range. Otherwise, you will receive the following error:

Error: : error upgrading connection: error dialing backend: dial tcp 172.17.<nn>.<nn>:10250: getsockopt: no route to host

Managed node group errors

If you receive the error "Instances failed to join the kubernetes cluster" in the AWS Management Console, ensure that either the cluster's private endpoint access is enabled, or that you have correctly configured CIDR blocks for public endpoint access. For more information, see Amazon EKS cluster endpoint access control.

If your managed node group encounters a health issue, Amazon EKS returns an error message to help you to diagnose the issue. The following error messages and their associated descriptions are shown below.

• AccessDenied: Amazon EKS or one or more of your managed nodes is failing to authenticate or authorize with your Kubernetes cluster API server. For more information about resolving this error, see Fixing AccessDenied errors for managed node groups.

• AmiIdNotFound: We couldn't find the AMI Id associated with your Launch Template. Make sure that the AMI exists and is shared with your account.

• AutoScalingGroupNotFound: We couldn't find the Auto Scaling group associated with the managed node group. You may be able to recreate an Auto Scaling group with the same settings to recover.

• ClusterUnreachable: Amazon EKS or one or more of your managed nodes is unable to to communicate with your Kubernetes cluster API server. This can happen if there are network disruptions or if API servers are timing out processing requests.

• Ec2SecurityGroupNotFound: We couldn't find the cluster security group for the cluster. You must recreate your cluster.

• Ec2SecurityGroupDeletionFailure: We could not delete the remote access security group for your managed node group. Remove any dependencies from the security group.

• Ec2LaunchTemplateNotFound: We couldn't find the Amazon EC2 launch template for your managed node group. You may be able to recreate a launch template with the same settings to recover.

• Ec2LaunchTemplateVersionMismatch: The Amazon EC2 launch template version for your managed node group does not match the version that Amazon EKS created. You may be able to revert to the version that Amazon EKS created to recover.

• IamInstanceProfileNotFound: We couldn't find the IAM instance profile for your managed node group. You may be able to recreate an instance profile with the same settings to recover.

• IamNodeRoleNotFound: We couldn't find the IAM role for your managed node group. You may be able to recreate an IAM role with the same settings to recover.

• AsgInstanceLaunchFailures: Your Auto Scaling group is experiencing failures while attempting to launch instances.

• NodeCreationFailure: Your launched instances are unable to register with your Amazon EKS cluster. Common causes of this failure are insufficient node IAM role permissions or lack of outbound internet access for the nodes. Your nodes must be able to access the internet using a public IP address to function properly. For more information, see VPC IP addressing. Your nodes must also have ports open to the internet. For more information, see Amazon EKS security group considerations.

• InstanceLimitExceeded: Your AWS account is unable to launch any more instances of the specified instance type. You may be able to request an Amazon EC2 instance limit increase to recover.

• InsufficientFreeAddresses: One or more of the subnets associated with your managed node group does not have enough available IP addresses for new nodes.

• InternalFailure: These errors are usually caused by an Amazon EKS server-side issue.

Fixing AccessDenied errors for managed node groups

The most common cause of AccessDenied errors when performing operations on managed node groups is missing the eks:node-manager ClusterRole or ClusterRoleBinding. Amazon EKS sets up these resources in your cluster as part of onboarding with managed node groups, and these are required for managing the node groups.

The ClusterRole may change over time, but it should look similar to the following example:

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: eks:node-manager
rules:
- apiGroups:
  - ''
  resources:
  - pods
  verbs:
  - get
  - list
  - watch
  - delete
- apiGroups:
  - ''
  resources:
  - nodes
  verbs:
  - get
  - list
  - watch
  - patch
- apiGroups:
  - ''
  resources:
  - pods/eviction
  verbs:
  - create               
            

The ClusterRoleBinding may change over time, but it should look similar to the following example:

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: eks:node-manager
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: eks:node-manager
subjects:
- apiGroup: rbac.authorization.k8s.io
  kind: User
  name: eks:node-manager

Verify that the eks:node-manager ClusterRole exists.

kubectl describe clusterrole eks:node-manager

If present, compare the output to the previous ClusterRole example.

Verify that the eks:node-manager ClusterRoleBinding exists.

kubectl describe clusterrolebinding eks:node-manager

If present, compare the output to the previous ClusterRoleBinding example.

If you've identified a missing or broken ClusterRole or ClusterRoleBinding as the cause of an AcessDenied error while requesting managed node group operations, you can restore them. Save the following contents to a file named eks-node-manager-role.yaml.

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: eks:node-manager
rules:
- apiGroups:
  - ''
  resources:
  - pods
  verbs:
  - get
  - list
  - watch
  - delete
- apiGroups:
  - ''
  resources:
  - nodes
  verbs:
  - get
  - list
  - watch
  - patch
- apiGroups:
  - ''
  resources:
  - pods/eviction
  verbs:
  - create
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: eks:node-manager
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: eks:node-manager
subjects:
- apiGroup: rbac.authorization.k8s.io
  kind: User
  name: eks:node-manager

Apply the file.

kubectl apply -f eks-node-manager-role.yaml

Retry the node group operation to see if that resolved your issue.

CNI log collection tool

The Amazon VPC CNI plugin for Kubernetes has its own troubleshooting script that is available on nodes at /opt/cni/bin/aws-cni-support.sh. You can use the script to collect diagnostic logs for support cases and general troubleshooting.

Use the following command to run the script on your node:

sudo bash /opt/cni/bin/aws-cni-support.sh

Note

If the script is not present at that location, then the CNI container failed to run. You can manually download and run the script with the following command:

curl -O https://raw.githubusercontent.com/awslabs/amazon-eks-ami/master/log-collector-script/linux/eks-log-collector.sh
sudo bash eks-log-collector.sh

The script collects the following diagnostic information. The CNI version that you have deployed can be earlier than the script version.

      This is version 0.6.1. New versions can be found at https://github.com/awslabs/amazon-eks-ami

Trying to collect common operating system logs... 
Trying to collect kernel logs... 
Trying to collect mount points and volume information... 
Trying to collect SELinux status... 
Trying to collect iptables information... 
Trying to collect installed packages... 
Trying to collect active system services... 
Trying to collect Docker daemon information... 
Trying to collect kubelet information... 
Trying to collect L-IPAMD information... 
Trying to collect sysctls information... 
Trying to collect networking information... 
Trying to collect CNI configuration information... 
Trying to collect running Docker containers and gather container data... 
Trying to collect Docker daemon logs... 
Trying to archive gathered information... 

	Done... your bundled logs are located in /var/log/eks_i-0717c9d54b6cfaa19_2020-03-24_0103-UTC_0.6.1.tar.gz

The diagnostic information is collected and stored at

/var/log/eks_i-0717c9d54b6cfaa19_2020-03-24_0103-UTC_0.6.1.tar.gz

Container runtime network not ready

You may receive a Container runtime network not ready error and authorization errors similar to the following:

4191 kubelet.go:2130] Container runtime network not ready: NetworkReady=false reason:NetworkPluginNotReady message:docker: network plugin is not ready: cni config uninitialized
4191 reflector.go:205] k8s.io/kubernetes/pkg/kubelet/kubelet.go:452: Failed to list *v1.Service: Unauthorized
4191 kubelet_node_status.go:106] Unable to register node "ip-10-40-175-122.ec2.internal" with API server: Unauthorized
4191 reflector.go:205] k8s.io/kubernetes/pkg/kubelet/kubelet.go:452: Failed to list *v1.Service: Unauthorized

The errors are most likely related to the AWS IAM Authenticator configuration map not being applied to the nodes. The configuration map provides the system:bootstrappers and system:nodes Kubernetes RBAC permissions for nodes to register to the cluster. For more information, see To enable nodes to join your cluster on the Self-managed nodes tab of Launching self-managed Amazon Linux nodes. Ensure that you specify the Role ARN of the instance role in the configuration map, not the Instance Profile ARN.

The authenticator does not recognize a Role ARN if it includes a path other than /, such as the following example:

arn:aws:iam::<111122223333>:role/<development/apps/prod-iam-role-NodeInstanceRole-621LVEXAMPLE>

When specifying a Role ARN in the configuration map that includes a path other than /, you must drop the path. The ARN above would be specified as the following:

arn:aws:iam::<111122223333>:role/<prod-iam-role-NodeInstanceRole-621LVEXAMPLE>

TLS handshake timeout

When a node is unable to establish a connection to the public API server endpoint, you may an error similar to the following error.

server.go:233] failed to run Kubelet: could not init cloud provider "aws": error finding instance i-1111f2222f333e44c: "error listing AWS instances: \"RequestError: send request failed\\ncaused by: Post  net/http: TLS handshake timeout\""

The kubelet process will continually respawn and test the API server endpoint. The error can also occur temporarily during any procedure that performs a rolling update of the cluster in the control plane, such as a configuration change or version update.

To resolve the issue, check the route table and security groups to ensure that traffic from the nodes can reach the public endpoint.

InvalidClientTokenId

If you're using IAM roles for service accounts for a pod or daemonset deployed to a cluster in a China Region, and haven't set the AWS_DEFAULT_REGION environment variable in the spec, the pod or daemonset may receive the following error:

An error occurred (InvalidClientTokenId) when calling the GetCallerIdentity operation: The security token included in the request is invalid

To resolve the issue, you need to add the AWS_DEFAULT_REGION environment variable to your pod or daemonset spec, as shown in the following example pod spec.

apiVersion: v1
kind: Pod
metadata:
  name: envar-demo
  labels:
    purpose: demonstrate-envars
spec:
  containers:
  - name: envar-demo-container
    image: gcr.io/google-samples/node-hello:1.0
    env:
    - name: AWS_DEFAULT_REGION
      value: "<region-code>"

VPC admission webhook certificate expiration

If the certificate used to sign the VPC admission webhook expires, the status for new Windows pod deployments stays at ContainerCreating. If you see this, view information about the pod in this state with the following command.

kubectl describe pod my-pod -n my-namespace

You see the following event in the returned output.

Warning FailedCreatePodSandBox 39s kubelet 

Check the expiration date of your certificate with the following command.

kubectl get secret \
    -n kube-system \
    vpc-admission-webhook-certs -o json | \
    jq -r '.data."cert.pem"' | \
    base64 --decode | \
    openssl x509 \
    -noout \
    -enddate | \
    cut -d= -f2

Output

May 27 14:23:00 2021 GMT

If your certificate is expired, you must renew it. For more information, see Renewing the VPC admission webhook certificate. Once you've deployed the new certificate, you must redeploy each pod that is stuck with a ContainerCreating status.