You can use a gateway to manage inbound and outbound traffic for your mesh to specify which traffic you want to enter or leave the mesh. Gateway configurations are applied to standalone Envoy proxies that are running at the edge of the mesh, rather than sidecar Envoy proxies running alongside your service workloads.
Unlike other mechanisms for controlling traffic entering your systems, such as the Kubernetes Ingress APIs, Red Hat OpenShift Service Mesh gateways use the full power and flexibility of traffic routing.
The Red Hat OpenShift Service Mesh gateway resource can use layer 4-6 load balancing properties, such as ports, to expose and configure Red Hat OpenShift Service Mesh TLS settings. Instead of adding application-layer traffic routing (L7) to the same API resource, you can bind a regular Red Hat OpenShift Service Mesh virtual service to the gateway and manage gateway traffic like any other data plane traffic in a service mesh.
Gateways are primarily used to manage ingress traffic, but you can also configure egress gateways. An egress gateway lets you configure a dedicated exit node for the traffic leaving the mesh. This enables you to limit which services have access to external networks, which adds security control to your service mesh. You can also use a gateway to configure a purely internal proxy.
Gateway example
A gateway resource describes a load balancer operating at the edge of the mesh receiving incoming or outgoing HTTP/TCP connections. The specification describes a set of ports that should be exposed, the type of protocol to use, SNI configuration for the load balancer, and so on.
The following example shows a sample gateway configuration for external HTTPS ingress traffic:
apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
name: ext-host-gwy
spec:
selector:
istio: ingressgateway # use istio default controller
servers:
- port:
number: 443
name: https
protocol: HTTPS
hosts:
- ext-host.example.com
tls:
mode: SIMPLE
serverCertificate: /tmp/tls.crt
privateKey: /tmp/tls.key
This gateway configuration lets HTTPS traffic from ext-host.example.com
into the mesh on port 443, but doesn’t specify any routing for the traffic.
To specify routing and for the gateway to work as intended, you must also bind the gateway to a virtual service. You do this using the virtual service’s gateways field, as shown in the following example:
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
name: virtual-svc
spec:
hosts:
- ext-host.example.com
gateways:
- ext-host-gwy
You can then configure the virtual service with routing rules for the external traffic.
Managing ingress traffic
In Red Hat OpenShift Service Mesh, the Ingress Gateway enables features such as monitoring, security, and route rules to apply to traffic that enters the cluster. Use a Service Mesh gateway to expose a service outside of the service mesh.
Determining the ingress IP and ports
Ingress configuration differs depending on if your environment supports an external load balancer. An external load balancer is set in the ingress IP and ports for the cluster. To determine if your cluster’s IP and ports are configured for external load balancers, run the following command. In this example, istio-system
is the name of the Service Mesh control plane project.
$ oc get svc istio-ingressgateway -n istio-system
That command returns the NAME
, TYPE
, CLUSTER-IP
, EXTERNAL-IP
, PORT(S)
, and AGE
of each item in your namespace.
If the EXTERNAL-IP
value is set, your environment has an external load balancer that you can use for the ingress gateway.
If the EXTERNAL-IP
value is <none>
, or perpetually <pending>
, your environment does not provide an external load balancer for the ingress gateway.
Determining ingress ports with a load balancer
Follow these instructions if your environment has an external load balancer.
Procedure
-
Run the following command to set the ingress IP and ports. This command sets a variable in your terminal.
$ export INGRESS_HOST=$(oc -n istio-system get service istio-ingressgateway -o jsonpath='{.status.loadBalancer.ingress[0].ip}')
-
Run the following command to set the ingress port.
$ export INGRESS_PORT=$(oc -n istio-system get service istio-ingressgateway -o jsonpath='{.spec.ports[?(@.name=="http2")].port}')
-
Run the following command to set the secure ingress port.
$ export SECURE_INGRESS_PORT=$(oc -n istio-system get service istio-ingressgateway -o jsonpath='{.spec.ports[?(@.name=="https")].port}')
-
Run the following command to set the TCP ingress port.
$ export TCP_INGRESS_PORT=$(kubectl -n istio-system get service istio-ingressgateway -o jsonpath='{.spec.ports[?(@.name=="tcp")].port}')
|
In some environments, the load balancer may be exposed using a hostname instead of an IP address. For that case, the ingress gateway’s EXTERNAL-IP value is not an IP address. Instead, it is a hostname, and the previous command fails to set the INGRESS_HOST environment variable.
In that case, use the following command to correct the INGRESS_HOST value:
|
$ export INGRESS_HOST=$(oc -n istio-system get service istio-ingressgateway -o jsonpath='{.status.loadBalancer.ingress[0].hostname}')
Determining ingress ports without a load balancer
If your environment does not have an external load balancer, determine the ingress ports and use a node port instead.
Procedure
-
Set the ingress ports.
$ export INGRESS_PORT=$(oc -n istio-system get service istio-ingressgateway -o jsonpath='{.spec.ports[?(@.name=="http2")].nodeport}')
-
Run the following command to set the secure ingress port.
$ export SECURE_INGRESS_PORT=$(oc -n istio-system get service istio-ingressgateway -o jsonpath='{.spec.ports[?(@.name=="https")].nodeport}')
-
Run the following command to set the TCP ingress port.
$ export TCP_INGRESS_PORT=$(kubectl -n istio-system get service istio-ingressgateway -o jsonpath='{.spec.ports[?(@.name=="tcp")].nodeport}')
Configuring an ingress gateway
An ingress gateway is a load balancer operating at the edge of the mesh that receives incoming HTTP/TCP connections. It configures exposed ports and protocols but does not include any traffic routing configuration. Traffic routing for ingress traffic is instead configured with routing rules, the same way as for internal service requests.
The following steps show how to create a gateway and configure a VirtualService
to expose a service in the Bookinfo sample application to outside traffic for paths /productpage
and /login
.
Procedure
-
Create a gateway to accept traffic.
-
Create a YAML file, and copy the following YAML into it.
Gateway example gateway.yaml
apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
name: bookinfo-gateway
spec:
selector:
istio: ingressgateway
servers:
- port:
number: 80
name: http
protocol: HTTP
hosts:
- "*"
-
Apply the YAML file.
$ oc apply -f gateway.yaml
-
Create a VirtualService
object to rewrite the host header.
-
Create a YAML file, and copy the following YAML into it.
Virtual service example
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
name: bookinfo
spec:
hosts:
- "*"
gateways:
- bookinfo-gateway
http:
- match:
- uri:
exact: /productpage
- uri:
prefix: /static
- uri:
exact: /login
- uri:
exact: /logout
- uri:
prefix: /api/v1/products
route:
- destination:
host: productpage
port:
number: 9080
-
Apply the YAML file.
-
Test that the gateway and VirtualService have been set correctly.
-
Set the Gateway URL.
export GATEWAY_URL=$(oc -n istio-system get route istio-ingressgateway -o jsonpath='{.spec.host}')
-
Set the port number. In this example, istio-system
is the name of the Service Mesh control plane project.
export TARGET_PORT=$(oc -n istio-system get route istio-ingressgateway -o jsonpath='{.spec.port.targetPort}')
-
Test a page that has been explicitly exposed.
curl -s -I "$GATEWAY_URL/productpage"
The expected result is 200
.