Backend TLS
Configure TLS to terminate for a specific backend workload.
When you configure an HTTPS listener, the Gateway terminates the TLS connection and decrypts the traffic. The Gateway then routes the decrypted traffic to the backend service.
However, you might have a specific backend workload that uses its own TLS certificate. In this case, you can configure the Gateway to originate a TLS connection that terminates at the backend service by using the Kubernetes Gateway API BackendTLSPolicy. For more information, see the Kubernetes Gateway API docs.
Before you begin
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Follow the Get started guide to install kgateway.
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Follow the Sample app guide to create a gateway proxy with an HTTP listener and deploy the httpbin sample app.
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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
Create a backend workload with a TLS certificate
The following example uses an NGINX server with a self-signed TLS certificate. For the configuration, see the test directory in the kgateway GitHub repository.
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Deploy the NGINX server with a self-signed TLS certificate.
kubectl apply -f https://raw.githubusercontent.com/kgateway-dev/kgateway/refs/heads/main/test/kubernetes/e2e/features/backendtls/inputs/nginx.yaml
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Verify that the NGINX server is running.
kubectl get pods -l app.kubernetes.io/name=nginx
Example output:
NAME READY STATUS RESTARTS AGE nginx 1/1 Running 0 9s
Create a BackendTLSPolicy
Create the BackendTLSPolicy for the NGINX workload. For more information, see the Kubernetes Gateway API docs.
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Install the experimental channel of the Kubernetes Gateway API so that you can use BackendTLSPolicy.
kubectl apply -f https://github.com/kubernetes-sigs/gateway-api/releases/download/v1.2.1/experimental-install.yaml
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Create a Kubernetes ConfigMap that has the public CA certificate for the NGINX server.
kubectl apply -f- <<EOF # public cert of self-signed cert loaded into nginx, see nginx.yaml # separate file so it can be deleted independently apiVersion: v1 data: ca.crt: | -----BEGIN CERTIFICATE----- MIIDFTCCAf2gAwIBAgIUG9Mdv3nOQ2i7v68OgjArU4lhBikwDQYJKoZIhvcNAQEL BQAwFjEUMBIGA1UEAwwLZXhhbXBsZS5jb20wHhcNMjUwNzA3MTA0MDQwWhcNMjYw NzA3MTA0MDQwWjAWMRQwEgYDVQQDDAtleGFtcGxlLmNvbTCCASIwDQYJKoZIhvcN AQEBBQADggEPADCCAQoCggEBANueqwfAApjTfg+nxIoKVK4sK/YlNICvdoEq1UEL StE9wfTv0J27uNIsfpMqCx0Ni9Rjt1hzjunc8HUJDeobMNxGaZmryQofrdJWJ7Uu t5jeLW/w0MelPOfFLsDiM5REy4WuPm2X6v1Z1N3N5GR3UNDOtDtsbjS1momvooLO 9WxPIr2cfmPqr81fyyD2ReZsMC/8lVs0PkA9XBplMzpSU53DWl5/Nyh2d1W5ENK0 Zw1l5Ze4UGUeohQMa5cD5hmZcBjOeJF8MuSTi3167KSopoqfgHTvC5IsBeWXAyZF 81ihFYAq+SbhUZeUlsxc1wveuAdBRzafcYkK47gYmbq1K60CAwEAAaNbMFkwFgYD VR0RBA8wDYILZXhhbXBsZS5jb20wCwYDVR0PBAQDAgeAMBMGA1UdJQQMMAoGCCsG AQUFBwMBMB0GA1UdDgQWBBSoa1Zu2o+pQ6sq2HcOjAglZkp01zANBgkqhkiG9w0B AQsFAAOCAQEADZq1EMw/jMl0z2LpPh8cXbP09BnfXhoFbpL4cFrcBNEyig0oPO0j YN1e4bfURNduFVnC/FDnZhR3FlAt8a6ozJAwmJp+nQCYFoDQwotSx12y5Bc9IXwd BRZaLgHYy2NjGp2UgAya2z23BkUnwOJwJNMCzuGw3pOsmDQY0diR8ZWmEYYEPheW 6BVkrikzUNXv3tB8LmWzxV9V3eN71fnP5u39IM/UQsOZGRUow/8tvN2/d0W4dHky t/kdgLKhf4gU2wXq/WbeqxlDSpjo7q/emNl59v1FHeR3eITSSjESU+dQgRsYaGEn SWP+58ApfCcURLpMxUmxkO1ayfecNJbmSQ== -----END CERTIFICATE----- kind: ConfigMap metadata: name: ca EOF
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Create the BackendTLSPolicy.
kubectl apply -f - <<EOF apiVersion: gateway.networking.k8s.io/v1alpha3 kind: BackendTLSPolicy metadata: name: nginx-tls-policy labels: app: nginx spec: targetRefs: - group: "" kind: Service name: nginx validation: hostname: "example.com" caCertificateRefs: - group: "" kind: ConfigMap name: ca EOF
Setting Description targetRefs
The service that you want the Gateway to originate a TLS connection to, such as the NGINX server. validation.hostname
The hostname that matches the NGINX server certificate. validation.caCertificateRefs
The ConfigMap that has the public CA certificate for the NGINX server. -
Create an HTTPRoute that routes traffic to the NGINX server on the
example.com
hostname and HTTPS port 8443. Note that the parent Gateway is the samplehttp
Gateway resource that you created before you began.kubectl apply -f - <<EOF apiVersion: gateway.networking.k8s.io/v1beta1 kind: HTTPRoute metadata: name: nginx-route labels: app: nginx spec: parentRefs: - name: http namespace: kgateway-system hostnames: - "example.com" rules: - backendRefs: - name: nginx port: 8443 EOF
Verify the TLS connection
Now that your TLS backend and routing resources are configured, verify the TLS connection.
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Get the external address of the gateway and save it in an environment variable. Note that it might take a few seconds for the gateway address to become available.
export INGRESS_GW_ADDRESS=$(kubectl get svc -n kgateway-system http -o jsonpath="{.status.loadBalancer.ingress[0]['hostname','ip']}") echo $INGRESS_GW_ADDRESS
kubectl port-forward svc/http -n kgateway-system 8080:8080
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Send a request to the NGINX server and verify that you get back a 200 HTTP response code.
curl -vi http://$INGRESS_GW_ADDRESS:8080/ -H "host: example.com:8080"
curl -vi http://localhost:8080/ -H "host: example.com:8080"
Example output:
* Host localhost:8080 was resolved. * IPv6: ::1 * IPv4: 127.0.0.1 * Trying [::1]:8080... * Connected to localhost (::1) port 8080 > GET / HTTP/1.1 > Host: example.com:8080 > User-Agent: curl/8.7.1 > Accept: */* > * Request completely sent off < HTTP/1.1 200 OK HTTP/1.1 200 OK
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Enable port-forwarding on the Gateway.
kubectl port-forward deploy/http -n kgateway-system 19000
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In your browser, open the Envoy stats page at http://127.0.0.1:19000/stats.
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Search for the following stats that indicate the TLS connection is working. The count increases each time that the Gateway sends a request to the NGINX server.
cluster.kube_default_nginx_8443.ssl.versions.TLSv1.2
: The number of TLSv1.2 connections from the Envoy gateway proxy to the NGINX server.cluster.kube_default_nginx_8443.ssl.handshake
: The number of successful TLS handshakes between the Envoy gateway proxy and the NGINX server.
Cleanup
You can remove the resources that you created in this guide.-
Delete the NGINX server and CA ConfigMap.
kubectl delete -f https://raw.githubusercontent.com/kgateway-dev/kgateway/refs/heads/main/test/kubernetes/e2e/features/backendtls/inputs/nginx.yaml kubectl delete -f https://raw.githubusercontent.com/kgateway-dev/kgateway/refs/heads/main/test/kubernetes/e2e/features/backendtls/inputs/configmap.yaml
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Delete the routing resources that your created for the NGINX server.
kubectl delete backendtlspolicy,configmap,httproute -A -l app=nginx
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If you want to re-create a BackendTLSPolicy after deleting one, restart the control plane.
⚠️Due to a known issue, if you don’t restart the control plane, you might notice requests that fail with aHTTP/1.1 400 Bad Request
error after creating the new BackendTLSPolicy.kubectl rollout restart -n kgateway-system deployment/kgateway