Introduction:

Building upon our exploration of Kubernetes networking evolution with the Gateway API, Part 2 tackles AWS Application Networking. 
This implementation of the Kubernetes Gateway API operates within Kubernetes clusters to manage AWS VPC Lattice resources. 
By using Kubernetes Custom Resource Definitions such as Gateway and HTTPRoute, AWS Application Networking orchestrates networking operations, enhancing the efficiency and security of networking within Kubernetes environments.

Amazon VPC Lattice:

Amazon VPC Lattice, a new feature of Amazon Virtual Private Cloud (Amazon VPC), is generally available, offering a unified approach to connect, secure, and monitor service communication. 

With the launch of Amazon VPC Lattice comes the introduction of the AWS Gateway API controller, an implementation of the Kubernetes Gateway API. This open-source standard interface enhances Kubernetes application networking through flexible, extensible, and role-oriented interfaces. 

The AWS Gateway API controller extends custom resources defined by the Gateway API, enabling the creation of VPC Lattice resources using Kubernetes APIs.

As organizations transition from monolithic applications to microservices architecture with Kubernetes, they gain agility and enable more frequent deployments. However, this shift introduces challenges related to application traffic management, security, monitoring, and routing. 
To address these concerns across ingress (north-south) and service-to-service communication (east-west), customers often rely on various tools like load balancers, service discovery mechanisms, service meshes, and monitoring agents.
Amazon VPC Lattice is a fully managed service built directly into the AWS network infrastructure. Amazon VPC Lattice allows you to:

• handle network connectivity seamlessly between services across VPCs and accounts
• discover these services spanning multiple Kubernetes clusters
• implement defense-in-depth strategy to secure communication between those services
• observe the request/response traffic across the services

To implement the features just described, you aren't required to develop custom code or required to manage Kubernetes sidecar proxies.

AWS Gateway API Controller:

Gateway API is an open-source project managed by the Kubernetes networking community. It is a collection of resources that model application networking in Kubernetes. Gateway API supports resources such as GatewayClass, Gateway, and Route that have been implemented by many vendors and have broad industry support.

Originally conceived as a successor to the well-known Ingress API, the benefits of the Gateway API include (but are not limited to) explicit support for many commonly used networking protocols, as well as tightly integrated support for Transport Layer Security (TLS).

When installed in your cluster, the controller watches for the creation of Gateway API resources such as gateways and routes and provisions corresponding Amazon VPC Lattice objects according to the mapping in the image below. 
The AWS Gateway API Controller is an open-source project and fully supported by Amazon.

As shown in the figure, there are different personas associated with different levels of control in the Kubernetes Gateway API:

• Infrastructure provider: Creates the Kubernetes GatewayClass to identify VPC Lattice as the GatewayClass.
• Cluster operator: Creates the Kubernetes Gateway, which gets information from VPC Lattice related to the service networks.
• Application developer: Creates HTTPRoute objects that specify how the traffic is redirected from the gateway to backend Kubernetes services.

AWS Kubernetes Gateway API resources and VPC Lattice resources correspond as follows:

Deploying the AWS Gateway API Controller:

Follow these instructions to create a cluster and deploy the AWS Gateway API Controller.

First, configure security group to receive traffic from the VPC Lattice network. You must set up security groups so that they allow all Pods communicating with VPC Lattice to allow traffic from the VPC Lattice managed prefix lists.

Lattice has both an IPv4 and IPv6 prefix lists available.

CLUSTER_SG=$(aws eks describe-cluster --name $EKS_CLUSTER_NAME --output json| jq -r '.cluster.resourcesVpcConfig.clusterSecurityGroupId')
PREFIX_LIST_ID=$(aws ec2 describe-managed-prefix-lists --query "PrefixLists[?PrefixListName=="\'com.amazonaws.$AWS_REGION.vpc-lattice\'"].PrefixListId" | jq -r '.[]')
aws ec2 authorize-security-group-ingress --group-id $CLUSTER_SG --ip-permissions "PrefixListIds=[{PrefixListId=${PREFIX_LIST_ID}}],IpProtocol=-1"
PREFIX_LIST_ID_IPV6=$(aws ec2 describe-managed-prefix-lists --query "PrefixLists[?PrefixListName=="\'com.amazonaws.$AWS_REGION.ipv6.vpc-lattice\'"].PrefixListId" | jq -r '.[]')
aws ec2 authorize-security-group-ingress --group-id $CLUSTER_SG --ip-permissions "PrefixListIds=[{PrefixListId=${PREFIX_LIST_ID_IPV6}}],IpProtocol=-1"

This step will install the controller and the CRDs (Custom Resource Definitions) required to interact with the Kubernetes Gateway API.

aws ecr-public get-login-password --region us-east-1 \
  | helm registry login --username AWS --password-stdin public.ecr.aws
helm install gateway-api-controller \
    oci://public.ecr.aws/aws-application-networking-k8s/aws-gateway-controller-chart \
    --version=v1.0.1 \
    --create-namespace \
    --set=aws.region=${AWS_REGION} \
    --set serviceAccount.annotations."eks\.amazonaws\.com/role-arn"="$LATTICE_IAM_ROLE" \
    --set=defaultServiceNetwork=${EKS_CLUSTER_NAME} \
    --namespace gateway-api-controller \
    --wait

The controller will now be running as a deployment:

kubectl get deployment -n gateway-api-controller
NAME                                                  READY   UP-TO-DATE   AVAILABLE   AGE
gateway-api-controller-aws-gateway-controller-chart   2/2     2            2           24s

Service network:

The Gateway API controller has been configured to create a VPC Lattice service network and associate a Kubernetes cluster VPC with it automatically. A service network is a logical boundary that's used to automatically implement service discovery and connectivity as well as apply access and observability policies to a collection of services.

It offers inter-application connectivity over HTTP, HTTPS, and gRPC protocols within a VPC. As of today, the controller supports HTTP and HTTPS.

Before creating a Gateway, we need to formalize the types of load balancing implementations that are available via the Kubernetes resource model with a GatewayClass.
 
The controller that listens to the Gateway API relies on an associated GatewayClass resource that the user can reference from their Gateway:

# Create a new Gateway Class for AWS VPC lattice provider
apiVersion: gateway.networking.k8s.io/v1
kind: GatewayClass
metadata:
  name: amazon-vpc-lattice
spec:
  controllerName: application-networking.k8s.aws/gateway-api-controller

The following YAML will create a Kubernetes Gateway resource which is associated with a VPC Lattice Service Network.

apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: ${EKS_CLUSTER_NAME}
  namespace: checkout
spec:
  gatewayClassName: amazon-vpc-lattice
  listeners:
  - name: http
    protocol: HTTP
    port: 80

Apply it and verify that eks-workshop gateway is created:

$ kubectl get gateway -n checkout
NAME                CLASS                ADDRESS   PROGRAMMED   AGE
eks-workshop        amazon-vpc-lattice             True         29s

Once the gateway is created, find the VPC Lattice service network. Wait until the status is Reconciled (this could take about five minutes).

$ kubectl describe gateway ${EKS_CLUSTER_NAME} -n checkout
apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
status:
   conditions:
      message: 'aws-gateway-arn: arn:aws:vpc-lattice:us-west-2:1234567890:servicenetwork/sn-03015ffef38fdc005'
      reason: Programmed
      status: "True"

$ kubectl wait --for=condition=Programmed gateway/${EKS_CLUSTER_NAME} -n checkout

Now you can see the associated Service Network created in the VPC console under the Lattice resources in the AWS console.

Configuring routes:

In this section, we will show how to use Amazon VPC Lattice for advanced traffic management with weighted routing for blue/green and canary-style deployments.

Let's deploy a modified version of the checkout microservice with the added prefix "Lattice" in the shipping options. Let's deploy this new version in a new namespace (checkoutv2) using Kustomize.

git clone https://github.com/seifrajhi/gateaway-api-vpc-lattice.git
kubectl apply -f gateaway-api-vpc-lattice/abtesting/

The checkoutv2 namespace now contains a second version of the application, while using the same redis instance in the checkout namespace.

$ kubectl get pods -n checkoutv2
NAME                        READY   STATUS    RESTARTS   AGE
checkout-854cd7cd66-s2blp   1/1     Running   0          26s

Now let's demonstrate how weighted routing works by creating HTTPRoute resources. 

First we'll create a TargetGroupPolicy that tells Lattice how to properly perform health checks on our checkout service:

kubectl apply -f gateaway-api-vpc-lattice/target-group-policy/target-group-policy.yaml

Now create the Kubernetes HTTPRoute route that distributes 75% traffic to checkoutv2 and remaining 25% traffic to checkout:

kubectl apply -f gateaway-api-vpc-lattice/routes/checkout-route.yaml

This creation of the associated resources may take 2–3 minutes, run the following command to wait for it to complete:

$kubectl wait -n checkout - timeout=3m \
 - for=jsonpath='{.status.parents[-1:].conditions[-1:].reason}'=ResolvedRefs httproute/checkoutroute

Once completed you will find the HTTPRoute's DNS name from HTTPRoute status (highlighted here on the message line):

$ kubectl describe httproute checkoutroute -n checkout
Name:         checkoutroute
Namespace:    checkout
Labels:       <none>
Annotations:  application-networking.k8s.aws/lattice-assigned-domain-name:
                checkoutroute-checkout-0d8e3f4604a069e36.7d67968.vpc-lattice-svcs.eu-west-1.on.aws
API Version:  gateway.networking.k8s.io/v1beta1
Kind:         HTTPRoute
...
Status:
  Parents:
    Conditions:
      Last Transition Time:  2023-06-12T16:42:08Z
      Message:               DNS Name: checkoutroute-checkout-0d8e3f4604a069e36.7d67968.vpc-lattice-svcs.us-east-2.on.aws
      Reason:                ResolvedRefs
      Status:                True
      Type:                  ResolvedRefs
...

Now you can see the associated Service created in the VPC Lattice console under the Lattice resources.

🚀 Summary:

In conclusion, the integration of Gateway API with AWS EKS and VPC Lattice has demonstrated significant improvements in networking efficiency and scalability.
 
By optimizing configurations, this integration enhances the performance of AWS EKS clusters and simplifies networking tasks. 

Overall, it represents a promising advancement in AWS EKS networking, paving the way for smoother operations and increased resilience.