eksctl create cluster will create a dedicated VPC for the cluster.
This is done in order to avoid interference with existing resources for a
variety of reasons, including security, but also because it is challenging to detect all settings in an existing VPC.
The default VPC CIDR used by
192.168.0.0/16. It is divided into 8 (
/19) subnets (3 private, 3 public & 2 reserved).
The initial nodegroup is created in public subnets, with SSH access disabled unless
--allow-ssh is specified.
The nodegroup by default allows inbound traffic from the control plane security group on ports 1025 - 65535.
us-east-1 eksctl only creates 2 public and 2 private subnets by default.
0.17.0 and onwards public subnets will have the property
MapPublicIpOnLaunch enabled, and
AssociatePublicIpAddress disabled in the Auto Scaling Group for the nodegroups. This means that when
creating a new nodegroup on a cluster made with an earlier version of
eksctl, the nodegroup must either be private
MapPublicIpOnLaunch enabled in its public subnets. Without one of these, the new nodes won't have access to
the internet and won't be able to download the basic add-ons (CNI plugin, kube-proxy, etc). To help set up
subnets correctly for old clusters you can use the new command
eksctl utils update-legacy-subnet-settings.
If the default functionality doesn't suit you, the following options are currently available.
Change VPC CIDR¶
If you need to setup peering with another VPC, or simply need a larger or smaller range of IPs, you can use
--vpc-cidr flag to
change it. Please refer to the AWS docs for guides on choosing CIDR blocks which are permitted for use in an AWS VPC.
Use private subnets for initial nodegroup¶
If you prefer to isolate the initial nodegroup from the public internet, you can use the
When used in conjunction with the
--ssh-access flag, the SSH port can only be accessed from inside the VPC.
--node-private-networking flag will result in outgoing traffic to go through the NAT gateway using its
Elastic IP. On the other hand, if the nodes are in a public subnet, the outgoing traffic won't go through the
NAT gateway and hence the outgoing traffic has the IP of each individual node.
Use an existing VPC: shared with kops¶
You can use the VPC of an existing Kubernetes cluster managed by kops. This feature is provided to facilitate migration and/or cluster peering.
If you have previously created a cluster with kops, e.g. using commands similar to this:
export KOPS_STATE_STORE=s3://kops kops create cluster cluster-1.k8s.local --zones=us-west-2c,us-west-2b,us-west-2a --networking=weave --yes
You can create an EKS cluster in the same AZs using the same VPC subnets (NOTE: at least 2 AZs/subnets are required):
eksctl create cluster --name=cluster-2 --region=us-west-2 --vpc-from-kops-cluster=cluster-1.k8s.local
Use existing VPC: other custom configuration¶
eksctl provides some, but not complete, flexibility for custom VPC and subnet topologies.
You can use an existing VPC by supplying private and/or public subnets using the
It is up to you to ensure the subnets you use are categorised correctly, as there is no simple way to verify whether a subnet is actually private or
public, because configurations vary.
Given these flags,
eksctl create cluster will determine the VPC ID automatically, but it will not create any routing tables or other
resources, such as internet/NAT gateways. It will, however, create dedicated security groups for the initial nodegroup and the control
You must ensure to provide at least 2 subnets in different AZs. There are other requirements that you will need to follow (listed below), but it's entirely up to you to address those. (For example, tagging is not strictly necessary, tests have shown that it is possible to create a functional cluster without any tags set on the subnets, however there is no guarantee that this will always hold and tagging is recommended.)
- all given subnets must be in the same VPC, within the same block of IPs
- a sufficient number IP addresses are available, based on needs
- sufficient number of subnets (minimum 2), based on needs
- subnets are tagged with at least the following:
kubernetes.io/cluster/<name>tag set to either
kubernetes.io/role/internal-elbtag set to
1for private subnets
kubernetes.io/role/elbtag set to
1for public subnets
- correctly configured internet and/or NAT gateways
- routing tables have correct entries and the network is functional
- NEW: all public subnets should have the property
Auto-assign public IPv4 addressin the AWS console)
There may be other requirements imposed by EKS or Kubernetes, and it is entirely up to you to stay up-to-date on any requirements and/or recommendations, and implement those as needed/possible.
Default security group settings applied by
eksctl may or may not be sufficient for sharing access with resources in other security
groups. If you wish to modify the ingress/egress rules of the security groups, you might need to use another tool to automate
changes, or do it via EC2 console.
When in doubt, don't use a custom VPC. Using
eksctl create cluster without any
--vpc-* flags will always configure the cluster
with a fully-functional dedicated VPC.
Create a cluster using a custom VPC with 2x private and 2x public subnets:
eksctl create cluster \ --vpc-private-subnets=subnet-0ff156e0c4a6d300c,subnet-0426fb4a607393184 \ --vpc-public-subnets=subnet-0153e560b3129a696,subnet-009fa0199ec203c37
or use the following equivalent config file:
apiVersion: eksctl.io/v1alpha5 kind: ClusterConfig metadata: name: my-test region: us-west-2 vpc: id: "vpc-11111" subnets: private: us-west-2a: id: "subnet-0ff156e0c4a6d300c" us-west-2c: id: "subnet-0426fb4a607393184" public: us-west-2a: id: "subnet-0153e560b3129a696" us-west-2c: id: "subnet-009fa0199ec203c37" nodeGroups: - name: ng-1
Create a cluster using a custom VPC with 3x private subnets and make initial nodegroup use those subnets:
eksctl create cluster \ --vpc-private-subnets=subnet-0ff156e0c4a6d300c,subnet-0549cdab573695c03,subnet-0426fb4a607393184 \ --node-private-networking
or use the following equivalent config file:
apiVersion: eksctl.io/v1alpha5 kind: ClusterConfig metadata: name: my-test region: us-west-2 vpc: id: "vpc-11111" subnets: private: us-west-2d: id: "subnet-0ff156e0c4a6d300c" us-west-2c: id: "subnet-0549cdab573695c03" us-west-2a: id: "subnet-0426fb4a607393184" nodeGroups: - name: ng-1 privateNetworking: true
Create a cluster using a custom VPC 4x public subnets:
eksctl create cluster \ --vpc-public-subnets=subnet-0153e560b3129a696,subnet-0cc9c5aebe75083fd,subnet-009fa0199ec203c37,subnet-018fa0176ba320e45
apiVersion: eksctl.io/v1alpha5 kind: ClusterConfig metadata: name: my-test region: us-west-2 vpc: id: "vpc-11111" subnets: public: us-west-2d: id: "subnet-0153e560b3129a696" us-west-2c: id: "subnet-0cc9c5aebe75083fd" us-west-2a: id: "subnet-009fa0199ec203c37" us-west-2b: id: "subnet-018fa0176ba320e45" nodeGroups: - name: ng-1
Further examples can be found in the repo's
Custom subnet topology¶
0.32.0 introduced further subnet topology customisation with the ability to:
- List multiple subnets per AZ in VPC configuration
- Specify subnets in nodegroup configuration
In earlier versions custom subnets had to be provided by availability zone, meaning just one subnet per AZ could be listed.
0.32.0 the identifying keys can be arbitrary.
vpc: id: "vpc-11111" subnets: public: public-one: # arbitrary key id: "subnet-0153e560b3129a696" public-two: id: "subnet-0cc9c5aebe75083fd" us-west-2b: # or list by AZ id: "subnet-018fa0176ba320e45" private: private-one: id: "subnet-0153e560b3129a696" private-two: id: "subnet-0cc9c5aebe75083fd"
If using the AZ as the identifying key, the
az value can be omitted.
If using an arbitrary string as the identifying key, like above, either:
idmust be set (
azmust be set (
If a user specifies a subnet by AZ without specifying CIDR and ID, a subnet in that AZ will be chosen from the VPC, arbitrarily if multiple such subnets exist.
A complete subnet spec must be provided, ie. both
declared in the VPC spec.
Nodegroups can be restricted to named subnets via the configuration. When specifying subnets on nodegroup configuration, use the identifying key as given in the VPC spec not the subnet id. For example:
vpc: id: "vpc-11111" subnets: public: public-one: id: "subnet-0153e560b3129a696" ... # subnet spec continued nodeGroups: - name: ng-1 instanceType: m5.xlarge desiredCapacity: 2 subnets: - public-one
Only one of
availabilityZones can be provided in nodegroup configuration.
When placing nodegroups inside a private subnet,
privateNetworking must be set to
on the nodegroup:
vpc: id: "vpc-11111" subnets: public: private-one: id: "subnet-0153e560b3129a696" ... # subnet spec continued nodeGroups: - name: ng-1 instanceType: m5.xlarge desiredCapacity: 2 privateNetworking: true subnets: - private-one
See here for a full configuration example.
Custom Cluster DNS address¶
There are two ways of overwriting the DNS server IP address used for all the internal and external DNS lookups. This
is the equivalent of the
--cluster-dns flag for the
The first, is through the
clusterDNS field. Config files accept a
string field called
clusterDNS with the IP address of the DNS server to use.
This will be passed to the
kubelet that in turn will pass it to the pods through the
apiVersion: eksctl.io/v1alpha5 kind: ClusterConfig metadata: name: cluster-1 region: eu-north-1 nodeGroups: - name: ng-1 clusterDNS: 169.254.20.10
Note that this configuration only accepts one IP address. To specify more than one address, use the
apiVersion: eksctl.io/v1alpha5 kind: ClusterConfig metadata: name: cluster-1 region: eu-north-1 nodeGroups: - name: ng-1 kubeletExtraConfig: clusterDNS: ["169.254.20.10","172.20.0.10"]
Custom Shared Node Security Group¶
eksctl will create and manage a shared node security group that allows communication between
unmanaged nodes and the cluster control plane and managed nodes.
If you wish to provide your own custom security group instead, you may override the
field in the config file:
vpc: sharedNodeSecurityGroup: sg-0123456789
By default, when creating the cluster,
eksctl will add rules to this security group to allow communication to and
from the default cluster security group that EKS creates. The default cluster security group is used by both
the EKS control plane and managed node groups.
If you wish to manage the security group rules yourself, you may prevent
eksctl from creating the rules
false in the config file:
vpc: sharedNodeSecurityGroup: sg-0123456789 manageSharedNodeSecurityGroupRules: false
The NAT Gateway for a cluster can be configured to be
Single (default) or
HighlyAvailable option will deploy a NAT Gateway in each Availability Zone of the Region, so that if
an AZ is down, nodes in the other AZs will still be able to communicate to the Internet.
It can be specified through the
--vpc-nat-mode CLI flag or in the cluster config file like the example below:
vpc: nat: gateway: HighlyAvailable # other options: Disable, Single (default)
See the complete example here.
Note: Specifying the NAT Gateway is only supported during cluster creation and it is not touched during a cluster upgrade. There are plans to support changing between different modes on cluster update in the future.
Managing Access to the Kubernetes API Server Endpoints¶
The default creation of an EKS cluster exposes the Kubernetes API server publicly but not directly from within the VPC subnets (public=true, private=false). Traffic destined for the API server from within the VPC must first exit the VPC networks (but not Amazon's network) and then re-enter to reach the API server.
The Kubernetes API server endpoint access for a cluster can be configured for public and private access when creating the cluster using the cluster config file. Example below:
vpc: clusterEndpoints: publicAccess: <true|false> privateAccess: <true|false>
There are some additional caveats when configuring Kubernetes API endpoint access:
- EKS doesn't allow one to create or update a cluster without at least one of private or public access being enabled.
- EKS does allow creating a configuration which allows only private access to be enabled, but eksctl doesn't support it during cluster creation as it prevents eksctl from being able to join the worker nodes to the cluster.
- Updating a cluster to have private only Kubernetes API endpoint access means that Kubernetes commands, by default,
kubectl) as well as
eksctl delete cluster,
eksctl utils write-kubeconfig, and possibly the command
eksctl utils update-kube-proxymust be run within the cluster VPC. This requires some changes to various AWS resources. See: EKS user guide A user can elect to supply vpc.extraCIDRs which will append additional CIDR ranges to the ControlPlaneSecurityGroup, allowing subnets outside the VPC to reach the kubernetes API endpoint.
The following is an example of how one could configure the Kubernetes API endpoint access using the
eksctl utils update-cluster-endpoints --name=<clustername> --private-access=true --public-access=false
To update the setting using a
ClusterConfig file, use:
eksctl utils update-cluster-endpoints -f config.yaml --approve
Note that if you don't pass a flag in it will keep the current value. Once you are satisfied with the proposed changes,
approve flag to make the change to the running cluster.
Restricting Access to the EKS Kubernetes Public API endpoint¶
The default creation of an EKS cluster exposes the Kubernetes API server publicly. To restrict access to the public API
endpoint to a set of CIDRs when creating a cluster, set the
vpc: publicAccessCIDRs: ["18.104.22.168/32", "22.214.171.124/24"]
To update the restrictions on an existing cluster, use:
eksctl utils set-public-access-cidrs --cluster=<cluster> 126.96.36.199/32,188.8.131.52/24
To update the restrictions using a
ClusterConfig file, set the new CIDRs in
vpc.publicAccessCIDRs and run:
eksctl utils set-public-access-cidrs -f config.yaml
This feature only applies to the public endpoint. The API server endpoint access configuration options won't change, and you will still have the option to disable the public endpoint so your cluster is not accessible from the internet. (Source: https://github.com/aws/containers-roadmap/issues/108#issuecomment-552766489)
Implementation notes: https://github.com/aws/containers-roadmap/issues/108#issuecomment-552698875