New: Amazon EKS Auto Mode automates routine tasks for load balancing. For more information, see:
Network traffic is load balanced at L4
of the OSI model. To load balance application traffic at L7
, you deploy a Kubernetes ingress
, which provisions an AWS Application Load Balancer. For more information, see Route application and HTTP traffic with Application Load Balancers. To learn more about the differences between the two types of load balancing, see Elastic Load Balancing features on the AWS website.
When you create a Kubernetes Service
of type LoadBalancer
, the AWS cloud provider load balancer controller creates AWS Classic Load Balancers by default, but can also create AWS Network Load Balancers. This controller is only receiving critical bug fixes in the future. For more information about using the AWS cloud provider load balancer , see AWS cloud provider load balancer controller in the Kubernetes documentation. Its use is not covered in this topic.
We recommend that you use version 2.7.2
or later of the AWS Load Balancer Controller instead of the AWS cloud provider load balancer controller. The AWS Load Balancer Controller creates AWS Network Load Balancers, but doesnât create AWS Classic Load Balancers. The remainder of this topic is about using the AWS Load Balancer Controller.
An AWS Network Load Balancer can load balance network traffic to Pods deployed to Amazon EC2 IP and instance targets, to AWS Fargate IP targets, or to Amazon EKS Hybrid Nodes as IP targets. For more information, see AWS Load Balancer Controller on GitHub.
PrerequisitesBefore you can load balance network traffic using the AWS Load Balancer Controller, you must meet the following requirements.
Have an existing cluster. If you donât have an existing cluster, see Get started with Amazon EKS. If you need to update the version of an existing cluster, see Update existing cluster to new Kubernetes version.
Have the AWS Load Balancer Controller deployed on your cluster. For more information, see Route internet traffic with AWS Load Balancer Controller. We recommend version 2.7.2
or later.
At least one subnet. If multiple tagged subnets are found in an Availability Zone, the controller chooses the first subnet whose subnet ID comes first lexicographically. The subnet must have at least eight available IP addresses.
If youâre using the AWS Load Balancer Controller version 2.1.1
or earlier, subnets must be tagged as follows. If using version 2.1.2
or later, this tag is optional. You might want to tag a subnet if you have multiple clusters running in the same VPC, or multiple AWS services sharing subnets in a VPC, and want more control over where load balancers are provisioned for each cluster. If you explicitly specify subnet IDs as an annotation on a service object, then Kubernetes and the AWS Load Balancer Controller use those subnets directly to create the load balancer. Subnet tagging isnât required if you choose to use this method for provisioning load balancers and you can skip the following private and public subnet tagging requirements. Replace my-cluster
with your cluster name.
Key â kubernetes.io/cluster/<my-cluster>
Value â shared
or owned
Your public and private subnets must meet the following requirements, unless you explicitly specify subnet IDs as an annotation on a service or ingress object. If you provision load balancers by explicitly specifying subnet IDs as an annotation on a service or ingress object, then Kubernetes and the AWS Load Balancer Controller use those subnets directly to create the load balancer and the following tags arenât required.
Private subnets â Must be tagged in the following format. This is so that Kubernetes and the AWS Load Balancer Controller know that the subnets can be used for internal load balancers. If you use eksctl
or an Amazon EKS AWS AWS CloudFormation template to create your VPC after March 26, 2020, then the subnets are tagged appropriately when theyâre created. For more information about the Amazon EKS AWS AWS CloudFormation VPC templates, see Create an Amazon VPC for your Amazon EKS cluster.
Key â kubernetes.io/role/internal-elb
Value â 1
Public subnets â Must be tagged in the following format. This is so that Kubernetes knows to use only those subnets for external load balancers instead of choosing a public subnet in each Availability Zone (based on the lexicographical order of the subnet IDs). If you use eksctl
or an Amazon EKS AWS CloudFormation template to create your VPC after March 26, 2020, then the subnets are tagged appropriately when theyâre created. For more information about the Amazon EKS AWS CloudFormation VPC templates, see Create an Amazon VPC for your Amazon EKS cluster.
Key â kubernetes.io/role/elb
Value â 1
If the subnet role tags arenât explicitly added, the Kubernetes service controller examines the route table of your cluster VPC subnets to determine if the subnet is private or public. We recommend that you donât rely on this behavior, and instead explicitly add the private or public role tags. The AWS Load Balancer Controller doesnât examine route tables, and requires the private and public tags to be present for successful auto discovery.
The configuration of your load balancer is controlled by annotations that are added to the manifest for your service. Service annotations are different when using the AWS Load Balancer Controller than they are when using the AWS cloud provider load balancer controller. Make sure to review the annotations for the AWS Load Balancer Controller before deploying services.
When using the Amazon VPC CNI plugin for Kubernetes, the AWS Load Balancer Controller can load balance to Amazon EC2 IP or instance targets and Fargate IP targets. When using Alternate compatible CNI plugins, the controller can only load balance to instance targets, unless you are load balancing to Amazon EKS Hybrid Nodes. For hybrid nodes, the controller can load balance IP targets. For more information about Network Load Balancer target types, see Target type in the User Guide for Network Load Balancers
If you want to add tags to the load balancer when or after itâs created, add the following annotation in your service specification. For more information, see AWS Resource Tags in the AWS Load Balancer Controller documentation.
service.beta.kubernetes.io/aws-load-balancer-additional-resource-tags
You can assign Elastic IP addresses to the Network Load Balancer by adding the following annotation. Replace the example values
with the Allocation IDs
of your Elastic IP addresses. The number of Allocation IDs
must match the number of subnets that are used for the load balancer. For more information, see the AWS Load Balancer Controller documentation.
service.beta.kubernetes.io/aws-load-balancer-eip-allocations: eipalloc-xxxxxxxxxxxxxxxxx,eipalloc-yyyyyyyyyyyyyyyyy
Amazon EKS adds one inbound rule to the nodeâs security group for client traffic and one rule for each load balancer subnet in the VPC for health checks for each Network Load Balancer that you create. Deployment of a service of type LoadBalancer
can fail if Amazon EKS attempts to create rules that exceed the quota for the maximum number of rules allowed for a security group. For more information, see Security groups in Amazon VPC quotas in the Amazon VPC User Guide. Consider the following options to minimize the chances of exceeding the maximum number of rules for a security group:
Request an increase in your rules per security group quota. For more information, see Requesting a quota increase in the Service Quotas User Guide.
Use IP targets, rather than instance targets. With IP targets, you can share rules for the same target ports. You can manually specify load balancer subnets with an annotation. For more information, see Annotations on GitHub.
Use an ingress, instead of a service of type LoadBalancer
, to send traffic to your service. The AWS Application Load Balancer requires fewer rules than Network Load Balancers. You can share an ALB across multiple ingresses. For more information, see Route application and HTTP traffic with Application Load Balancers. You canât share a Network Load Balancer across multiple services.
Deploy your clusters to multiple accounts.
If your Pods run on Windows in an Amazon EKS cluster, a single service with a load balancer can support up to 1024 back-end Pods. Each Pod has its own unique IP address.
We recommend only creating new Network Load Balancers with the AWS Load Balancer Controller. Attempting to replace existing Network Load Balancers created with the AWS cloud provider load balancer controller can result in multiple Network Load Balancers that might cause application downtime.
You can create a network load balancer with IP or instance targets.
Create network load balancerâââIP TargetsYou can use IP targets with Pods deployed to Amazon EC2 nodes, Fargate, or Amazon EKS Hybrid Nodes. Your Kubernetes service must be created as type LoadBalancer
. For more information, see Type LoadBalancer in the Kubernetes documentation.
To create a load balancer that uses IP targets, add the following annotations to a service manifest and deploy your service. The external
value for aws-load-balancer-type
is what causes the AWS Load Balancer Controller, rather than the AWS cloud provider load balancer controller, to create the Network Load Balancer. You can view a sample service manifest with the annotations.
service.beta.kubernetes.io/aws-load-balancer-type: "external"
service.beta.kubernetes.io/aws-load-balancer-nlb-target-type: "ip"
Note
If youâre load balancing to IPv6
Pods, add the following annotation. You can only load balance over IPv6
to IP targets, not instance targets. Without this annotation, load balancing is over IPv4
.
service.beta.kubernetes.io/aws-load-balancer-ip-address-type: dualstack
Network Load Balancers are created with the internal
aws-load-balancer-scheme
, by default. You can launch Network Load Balancers in any subnet in your clusterâs VPC, including subnets that werenât specified when you created your cluster.
Kubernetes examines the route table for your subnets to identify whether they are public or private. Public subnets have a route directly to the internet using an internet gateway, but private subnets do not.
If you want to create a Network Load Balancer in a public subnet to load balance to Amazon EC2 nodes (Fargate can only be private), specify internet-facing
with the following annotation:
service.beta.kubernetes.io/aws-load-balancer-scheme: "internet-facing"
Note
The service.beta.kubernetes.io/aws-load-balancer-type: "nlb-ip"
annotation is still supported for backwards compatibility. However, we recommend using the previous annotations for new load balancers instead of service.beta.kubernetes.io/aws-load-balancer-type: "nlb-ip"
.
Do not edit the annotations after creating your service. If you need to modify it, delete the service object and create it again with the desired value for this annotation.
The AWS cloud provider load balancer controller creates Network Load Balancers with instance targets only. Version 2.2.0
and later of the AWS Load Balancer Controller also creates Network Load Balancers with instance targets. We recommend using it, rather than the AWS cloud provider load balancer controller, to create new Network Load Balancers. You can use Network Load Balancer instance targets with Pods deployed to Amazon EC2 nodes, but not to Fargate. To load balance network traffic across Pods deployed to Fargate, you must use IP targets.
To deploy a Network Load Balancer to a private subnet, your service specification must have the following annotations. You can view a sample service manifest with the annotations. The external
value for aws-load-balancer-type
is what causes the AWS Load Balancer Controller, rather than the AWS cloud provider load balancer controller, to create the Network Load Balancer.
service.beta.kubernetes.io/aws-load-balancer-type: "external"
service.beta.kubernetes.io/aws-load-balancer-nlb-target-type: "instance"
Network Load Balancers are created with the internal
aws-load-balancer-scheme
, by default. For internal Network Load Balancers, your Amazon EKS cluster must be configured to use at least one private subnet in your VPC. Kubernetes examines the route table for your subnets to identify whether they are public or private. Public subnets have a route directly to the internet using an internet gateway, but private subnets do not.
If you want to create an Network Load Balancer in a public subnet to load balance to Amazon EC2 nodes, specify internet-facing
with the following annotation:
service.beta.kubernetes.io/aws-load-balancer-scheme: "internet-facing"
Important
Do not edit the annotations after creating your service. If you need to modify it, delete the service object and create it again with the desired value for this annotation.
At least one public or private subnet in your cluster VPC.
Have the AWS Load Balancer Controller deployed on your cluster. For more information, see Route internet traffic with AWS Load Balancer Controller. We recommend version 2.7.2
or later.
If youâre deploying to Fargate, make sure you have an available private subnet in your VPC and create a Fargate profile. If youâre not deploying to Fargate, skip this step. You can create the profile by running the following command or in the AWS Management Console using the same values for name
and namespace
that are in the command. Replace the example values
with your own.
eksctl create fargateprofile \
--cluster my-cluster \
--region region-code \
--name nlb-sample-app \
--namespace nlb-sample-app
Deploy a sample application.
Create a namespace for the application.
kubectl create namespace nlb-sample-app
Save the following contents to a file named sample-deployment.yaml
file on your computer.
apiVersion: apps/v1
kind: Deployment
metadata:
name: nlb-sample-app
namespace: nlb-sample-app
spec:
replicas: 3
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: public.ecr.aws/nginx/nginx:1.23
ports:
- name: tcp
containerPort: 80
Apply the manifest to the cluster.
kubectl apply -f sample-deployment.yaml
Create a service with an internet-facing Network Load Balancer that load balances to IP targets.
Save the following contents to a file named sample-service.yaml
file on your computer. If youâre deploying to Fargate nodes, remove the service.beta.kubernetes.io/aws-load-balancer-scheme: internet-facing
line.
apiVersion: v1
kind: Service
metadata:
name: nlb-sample-service
namespace: nlb-sample-app
annotations:
service.beta.kubernetes.io/aws-load-balancer-type: external
service.beta.kubernetes.io/aws-load-balancer-nlb-target-type: ip
service.beta.kubernetes.io/aws-load-balancer-scheme: internet-facing
spec:
ports:
- port: 80
targetPort: 80
protocol: TCP
type: LoadBalancer
selector:
app: nginx
Apply the manifest to the cluster.
kubectl apply -f sample-service.yaml
Verify that the service was deployed.
kubectl get svc nlb-sample-service -n nlb-sample-app
An example output is as follows.
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
sample-service LoadBalancer 10.100.240.137 k8s-nlbsampl-nlbsampl-xxxxxxxxxx-xxxxxxxxxxxxxxxx.elb.region-code.amazonaws.com 80:32400/TCP 16h
Note
The values for 10.100.240.137
and xxxxxxxxxx
-xxxxxxxxxxxxxxxx
will be different than the example output (they will be unique to your load balancer) and us-west-2
may be different for you, depending on which AWS Region that your cluster is in.
Open the Amazon EC2 AWS Management Console. Select Target Groups (under Load Balancing) in the left navigation pane. In the Name column, select the target groupâs name where the value in the Load balancer column matches a portion of the name in the EXTERNAL-IP
column of the output in the previous step. For example, youâd select the target group named k8s-default-samplese-
if your output were the same as the previous output. The Target type is xxxxxxxxxx
IP
because that was specified in the sample service manifest.
Select the Target group and then select the Targets tab. Under Registered targets, you should see three IP addresses of the three replicas deployed in a previous step. Wait until the status of all targets is healthy before continuing. It might take several minutes before all targets are healthy
. The targets might be in an unhealthy
state before changing to a healthy
state.
Send traffic to the service replacing xxxxxxxxxx-xxxxxxxxxxxxxxxx
and us-west-2
with the values returned in the output for a previous step for EXTERNAL-IP
. If you deployed to a private subnet, then youâll need to view the page from a device within your VPC, such as a bastion host. For more information, see Linux Bastion Hosts on AWS.
curl k8s-default-samplese-xxxxxxxxxx-xxxxxxxxxxxxxxxx.elb.region-code.amazonaws.com
An example output is as follows.
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
[...]
When youâre finished with the sample deployment, service, and namespace, remove them.
kubectl delete namespace nlb-sample-app
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