Access AWS Lambda with a service account

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Backends

AWS Lambda

Associate an IAM role with a gateway proxy service account, and configure kgateway to use that service account to access AWS Lambda.

About

Amazon Web Services (AWS) offers the ability to associate an IAM role with a Kubernetes service account, also known as creating an IRSA. Kgateway supports discovering and invoking AWS Lambda functions by using an IRSA. For more information, see the AWS documentation.

In this guide, you follow these steps:

AWS resources:

Associate your EKS cluster with an IAM OIDC provider
Create an IAM policy that allows interactions with Lambda functions
Create an IAM role that associates the IAM policy with the gateway proxy service account (an IRSA)
Deploy the Amazon EKS Pod Identity Webhook to your cluster
Create a Lambda function for testing

Kgateway resources:

Install kgateway
Annotate the gateway proxy service account with the IRSA
Set up routing to your function by creating Upstream and HTTPRoute resources

⚠️

This guide requires you to enable IAM settings in your EKS cluster, such as the AWS Pod Identity Webhook, before you deploy kgateway components that are created during installation, such as the Gateway CRD and the gateway proxy service account. You might use this guide with a fresh EKS test cluster to try out Lambda function invocation with kgateway service accounts.

Configure AWS IAM resources

Save your AWS details, and create an IRSA for the gateway proxy pod to use.

Save the region where your Lambda functions exist, the region where your EKS cluster exists, your cluster name, and the ID of the AWS account.

export AWS_LAMBDA_REGION=<lambda_function_region>
export AWS_CLUSTER_REGION=<cluster_region>
export CLUSTER_NAME=<cluster_name>
export AWS_ACCOUNT_ID=<account_id>

Check whether your EKS cluster has an OIDC provider.
```
export OIDC_PROVIDER=$(aws eks describe-cluster --name ${CLUSTER_NAME} --region ${AWS_CLUSTER_REGION} --query "cluster.identity.oidc.issuer" --output text | sed -e "s/^https:\/\///")
echo $OIDC_PROVIDER
```
- If an OIDC provider in the format oidc.eks.<region>.amazonaws.com/id/<cluster_id> is returned, continue to the next step.
- If an OIDC provider is not returned, follow the AWS documentation to Create an IAM OIDC provider for your cluster, and then run this command again to save the OIDC provider in an environment variable.

Create an IAM policy to allow access to the following four Lambda actions. Note that the permissions to discover and invoke functions are listed in the same policy. In a more advanced setup, you might separate discovery and invocation permissions into two IAM policies.

cat >policy.json <<EOF
{
   "Version": "2012-10-17",
   "Statement": [
       {
           "Effect": "Allow",
           "Action": [
               "lambda:ListFunctions",
               "lambda:InvokeFunction",
               "lambda:GetFunction",
               "lambda:InvokeAsync"
           ],
           "Resource": "*"
       }
   ]
}
EOF

aws iam create-policy --policy-name kgateway-lambda-policy --policy-document file://policy.json

Use an IAM role to associate the policy with the Kubernetes service account for the HTTP gateway proxy, which assumes this role to invoke Lambda functions. For more information about these steps, see the AWS documentation.

Create the following IAM role. Note that the service account name http in the kgateway-system namespace is specified, because in later steps you create an HTTP gateway named http.

cat >role.json <<EOF
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Federated": "arn:aws:iam::${AWS_ACCOUNT_ID}:oidc-provider/${OIDC_PROVIDER}"
      },
      "Action": "sts:AssumeRoleWithWebIdentity",
      "Condition": {
        "StringEquals": {
          "${OIDC_PROVIDER}:sub": [
            "system:serviceaccount:kgateway-system:http"
          ]
        }
      }
    }
  ]
}
EOF

aws iam create-role --role-name kgateway-lambda-role --assume-role-policy-document file://role.json

Attach the IAM role to the IAM policy. This IAM role for the service account is known as an IRSA.

aws iam attach-role-policy --role-name kgateway-lambda-role --policy-arn=arn:aws:iam::${AWS_ACCOUNT_ID}:policy/kgateway-lambda-policy

Verify that the policy is attached to the role.

aws iam list-attached-role-policies --role-name kgateway-lambda-role

Example output:

{
    "AttachedPolicies": [
        {
            "PolicyName": "kgateway-lambda-policy",
            "PolicyArn": "arn:aws:iam::111122223333:policy/kgateway-lambda-policy"
        }
    ]
}

Deploy the Amazon EKS Pod Identity Webhook

Before you install kgateway, deploy the Amazon EKS Pod Identity Webhook, which allows pods’ service accounts to use AWS IAM roles. When you create the kgateway proxy in the next section, this webhook mutates the proxy’s service account so that it can assume your IAM role to invoke Lambda functions.

In your EKS cluster, install cert-manager, which is a prerequisite for the webhook.

wget https://github.com/cert-manager/cert-manager/releases/download/v1.12.4/cert-manager.yaml
kubectl apply -f cert-manager.yaml

Verify that all cert-manager pods are running.
```
kubectl get pods -n cert-manager
```

Deploy the Amazon EKS Pod Identity Webhook.

kubectl apply -f https://raw.githubusercontent.com/solo-io/workshops/refs/heads/master/gloo-gateway/1-18/enterprise/lambda/data/steps/deploy-amazon-pod-identity-webhook/auth.yaml
kubectl apply -f https://raw.githubusercontent.com/solo-io/workshops/refs/heads/master/gloo-gateway/1-18/enterprise/lambda/data/steps/deploy-amazon-pod-identity-webhook/deployment-base.yaml
kubectl apply -f https://raw.githubusercontent.com/solo-io/workshops/refs/heads/master/gloo-gateway/1-18/enterprise/lambda/data/steps/deploy-amazon-pod-identity-webhook/mutatingwebhook.yaml
kubectl apply -f https://raw.githubusercontent.com/solo-io/workshops/refs/heads/master/gloo-gateway/1-18/enterprise/lambda/data/steps/deploy-amazon-pod-identity-webhook/service.yaml

Verify that the webhook deployment completes.

kubectl rollout status deploy/pod-identity-webhook

Install kgateway

Be sure that you deployed the Amazon EKS Pod Identity Webhook to your cluster first before you continue to install kgateway.

Deploy the Kubernetes Gateway API CRDs.

kubectl apply -f https://github.com/kubernetes-sigs/gateway-api/releases/download/v1.2.1/standard-install.yaml

Deploy the kgateway CRDs by using Helm.

helm upgrade -i --create-namespace --namespace kgateway-system --version v2.0.0-main kgateway-crds oci://cr.kgateway.dev/kgateway-dev/charts/kgateway-crds

Install kgateway by using Helm.

helm upgrade -i --namespace kgateway-system --version v2.0.0-main kgateway oci://cr.kgateway.dev/kgateway-dev/charts/kgateway

Make sure that kgateway is running.

kubectl get pods -n kgateway-system

Example output:

NAME                        READY   STATUS    RESTARTS   AGE
kgateway-5495d98459-46dpk   1/1     Running   0          19s

Annotate the gateway proxy service account

Create a GatewayParameters resource to specify the eks.amazonaws.com/role-arn IRSA annotation for the gateway proxy service account.

kubectl apply -f- <<EOF
apiVersion: gateway.kgateway.dev/v1alpha1
kind: GatewayParameters
metadata:
  name: http-lambda
  namespace: kgateway-system
spec:
  kube:
    serviceAccount:
      extraAnnotations:
        eks.amazonaws.com/role-arn: arn:aws:iam::${AWS_ACCOUNT_ID}:role/kgateway-lambda-role
EOF

Update the http Gateway resource to add a reference to the http-lambda GatewayParameters.

kubectl apply -f- <<EOF
kind: Gateway
apiVersion: gateway.networking.k8s.io/v1
metadata:
  name: http
  namespace: kgateway-system
  annotations:
spec:
  gatewayClassName: kgateway
  infrastructure:
    parametersRef:
      name: http-lambda
      group: gateway.kgateway.dev
      kind: GatewayParameters        
  listeners:
  - protocol: HTTP
    port: 8080
    name: http
    allowedRoutes:
      namespaces:
        from: All
EOF

Check the status of the gateway to make sure that your configuration is accepted. Note that in the output, a NoConflicts status of False indicates that the gateway is accepted and does not conflict with other gateway configuration.
```
kubectl get gateway http -n kgateway-system -o yaml
```
Verify that the http service account has the eks.amazonaws.com/role-arn: arn:aws:iam::${AWS_ACCOUNT_ID}:role/kgateway-lambda-role annotation.
```
kubectl describe serviceaccount http -n kgateway-system
```

Create a Lambda function

Create an AWS Lambda function to test kgateway routing.

Log in to the AWS console and navigate to the Lambda page.
Click the Create Function button.
Name the function echo and click Create function.

Replace the default contents of index.mjs with the following Node.js function, which returns a response body that contains exactly what was sent to the function in the request body.

export const handler = async(event) => {
    const response = {
        statusCode: 200,
        body: `Response from AWS Lambda. Here's the request you just sent me: ${JSON.stringify(event)}`
    };
    return response;
};

Click Deploy.

Set up routing to your function

Create kgateway Backend and HTTPRoute resources to route requests to the Lambda function.

Create a Backend resource that references the AWS region, IAM role, and echo function that you created.

kubectl apply -f - <<EOF
apiVersion: gateway.kgateway.dev/v1alpha1
kind: Backend
metadata:
  name: lambda
  namespace: kgateway-system
spec:
  type: AWS
  aws:
    region: ${AWS_LAMBDA_REGION}
    accountId: "${AWS_ACCOUNT_ID}"
    lambda:
      functionName: echo
EOF

Create an HTTPRoute resource that references the lambda Backend.

kubectl apply -f - <<EOF
apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: lambda
  namespace: kgateway-system
spec:
  parentRefs:
    - name: http
      namespace: kgateway-system
  rules:
  - matches:
    - path:
        type: PathPrefix
        value: /echo
    backendRefs:
    - name: lambda
      namespace: kgateway-system
      group: gateway.kgateway.dev
      kind: Backend
EOF

Get the external address of the gateway and save it in an environment variable.

export INGRESS_GW_ADDRESS=$(kubectl get svc -n kgateway-system http -o jsonpath="{.status.loadBalancer.ingress[0]['hostname','ip']}")
echo $INGRESS_GW_ADDRESS

kubectl port-forward deployment/http -n kgateway-system 8080:8080

Confirm that kgateway correctly routes requests to Lambda by sending a curl request to the echo function. Note that the first request might take a few seconds to process, because the AWS Security Token Service (STS) credential request must be performed first. However, after the credentials are cached, subsequent requests are processed more quickly.
curl $INGRESS_GW_ADDRESS:8080/echo -d '{"key1":"value1", "key2":"value2"}' -X POST
curl localhost:8080/echo -d '{"key1":"value1", "key2":"value2"}' -X POST
Example response:
```
{"statusCode":200,"body":"Response from AWS Lambda. Here's the request you just sent me: {\"key1\":\"value1\",\"key2\":\"value2\"}"}% 
```

At this point, kgateway is routing directly to the echo Lambda function using an IRSA!

Cleanup

You can remove the resources that you created in this guide.

Resources for the `echo` function

Delete the lambda HTTPRoute and lambda Backend.

kubectl delete HTTPRoute lambda -n kgateway-system
kubectl delete Backend lambda -n kgateway-system

Use the AWS Lambda console to delete the echo test function.

IRSA authorization (optional)

If you no longer need to access Lambda functions from kgateway:

Delete the GatewayParameters resources.

kubectl delete GatewayParameters http-lambda -n kgateway-system

Remove the reference to the http-lambda GatewayParameters from the http Gateway.

kubectl apply -f- <<EOF
kind: Gateway
apiVersion: gateway.networking.k8s.io/v1
metadata:
  name: http
  namespace: kgateway-system
spec:
  gatewayClassName: kgateway
  listeners:
  - protocol: HTTP
    port: 8080
    name: http
    allowedRoutes:
      namespaces:
        from: All
EOF

Delete the pod identity webhook.

kubectl delete deploy pod-identity-webhook

Remove cert-manager.

kubectl delete -f cert-manager.yaml -n cert-manager
kubectl delete ns cert-manager

Delete the AWS IAM resources that you created.

aws iam detach-role-policy --role-name kgateway-lambda-role --policy-arn=arn:aws:iam::${AWS_ACCOUNT_ID}:policy/kgateway-lambda-policy
aws iam delete-role --role-name kgateway-lambda-role
aws iam delete-policy --policy-arn=arn:aws:iam::${AWS_ACCOUNT_ID}:policy/kgateway-lambda-policy

Access AWS Lambda with a credentials secret

Access AWS Lambda with a service account

About

Configure AWS IAM resources

Deploy the Amazon EKS Pod Identity Webhook

Install kgateway

Annotate the gateway proxy service account

Create a Lambda function

Set up routing to your function

Cleanup

Resources for the echo function

IRSA authorization (optional)

Resources for the `echo` function