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.

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.

Worker Nodes Fail to Join Cluster

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

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

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

• The worker node is not tagged as being owned by the cluster. Your worker 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 worker nodes may not be able to access the cluster using a public IP address. Ensure that worker nodes deployed in public subnets are assigned a public IP address. If not, you can associate an elastic IP address to a worker 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 worker 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.

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:master 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. Also, the AWS IAM Authenticator for Kubernetes uses the AWS SDK for Go to authenticate against your Amazon EKS 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. If the AWS CLI is configured properly for your user, then the AWS IAM Authenticator for Kubernetes can find those credentials as well. 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 --region region-code eks update-kubeconfig --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 or watch a video about how to map a user.

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.

• 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.

• 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 worker node IAM role permissions or lack of outbound internet access for the nodes.

• 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.

• AccessDenied: Amazon EKS or one or more of your managed nodes is unable to communicate with your cluster API server.

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

CNI Log Collection Tool

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

The script collects the following diagnostic information:

• L-IPAMD introspection data

• Metrics

• Kubelet introspection data

• ifconfig output

• ip rule show output

• iptables-save output

• iptables -nvL output

• iptables -nvL -t nat output

• A dump of the CNI configuration

• Kubelet logs

• Stored /var/log/messages

• Worker node's route table information (via ip route)

• The sysctls output of /proc/sys/net/ipv4/conf/{all,default,eth0}/rp_filter

Use the following command to run the script on your worker 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 https://raw.githubusercontent.com/aws/amazon-vpc-cni-k8s/master/scripts/aws-cni-support.sh | sudo bash

The diagnostic information is collected and stored at /var/log/aws-routed-eni/aws-cni-support.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 worker nodes. The configuration map provides the system:bootstrappers and system:nodes Kubernetes RBAC permissions for worker nodes to register to the cluster. For more information, see To enable worker nodes to join your cluster on the Self-managed nodes tab of Launching Amazon EKS Linux Worker 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 worker 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 worker nodes can reach the public endpoint.

Error: ErrImagePull

If you have 1.12 worker nodes deployed into a China region, you may see the following text in an error message in your kubelet logs:

Failed: Failed to pull image "xxxxxx.dkr.ecr.region-code.amazonaws.com.cn"

To resolve the issue, ensure that you pull the image from an Amazon Elastic Container Registry repository that is in the same region that your worker node is deployed in.