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Getting traffic into a mesh

Using Istio APIs, you can configure gateway proxies that were installed using gateway injection to accept traffic originating from outside the mesh, and route that traffic to the services within the mesh.

You can expose gateway proxies to traffic outside a cluster by using either a LoadBalancer type Service or OpenShift Routes.

About configuring a gateway installed using gateway injection to accept ingress traffic

When you install a gateway using gateway injection you can configure it to receive ingress traffic using the Istio Gateway and VirtualService resources in combination. The Istio Gateway resource describes a load balancer operating at the edge of the mesh that receives incoming or outgoing HTTP/TCP connections. The Gateway specification describes a set of ports that should be exposed, the type of protocol to use, and the Server Name Indication (SNI) configuration for the load balancer. VirtualServices define routing rules to apply to an Istio Gateway, similar to how you can use VirtualServices to define routing rules for internal mesh traffic.

In the following example an Istio Gateway resource configures a gateway proxy to act as an entry point for external traffic. This configuration exposes port 443 (HTTPS) for the host, bookinfo.com. The example configuration applies to pods with the istio: ingressgateway label. The tls mode is configured as SIMPLE, which terminates the incoming HTTPS traffic using the certificate and private key the example provides.

Sample configuration
apiVersion: networking.istio.io/v1
kind: Gateway
metadata:
  name: bookinfo-gateway
  namespace: bookinfo
spec:
  selector:
    istio: ingressgateway
  servers:
  - port:
      number: 443
      name: https-443
      protocol: HTTPS
    hosts:
    - bookinfo.com
    tls:
      mode: SIMPLE
      serverCertificate: /etc/certs/servercert.pem
      privateKey: /etc/certs/privatekey.pem

The following VirtualService is bound to the Istio Gateway resource shown in the previous example configuration. The specification defines rules to route traffic with the /reviews/ path prefix to the reviews service in the bookinfo namespace. The VirtualService explicitly references the Gateway resource shown previously. This ensures that the routing rules are only applied to the traffic that enters through the specified gateway.

Sample configuration
kind: VirtualService
metadata:
  name: bookinfo-rule
  namespace: bookinfo
spec:
  hosts:
  - bookinfo.com
  gateways:
  - bookinfo/bookinfo-gateway
  http:
  - match:
    - uri:
        prefix: /reviews/
    route:
    - destination:
        port:
          number: 9080
        host: reviews.bookinfo.svc.cluster.local
Additional resources

Exposing a service by using the Istio Gateway and VirtualService resources

This procedure uses the Istio Gateway and VirtualService resources to configure a gateway that was deployed by using gateway injection. The resources configure the gateway to expose a service in the mesh to traffic outside the mesh. Then, you expose the gateway to traffic outside the cluster by setting the Service for the gateway to type LoadBalancer.

Prerequisites

  • You have installed an Istio gateway using gateway injection.

Procedure

  1. Create namespace called httpbin by running the following command:

    $ oc create namespace httpbin

  2. Enable sidecar injection in the namespace. If you are using the InPlace upgrade strategy, run the following command:

    $ oc label namespace httpbin istio-injection=enabled

    If you are using the RevisionBased upgrade strategy, run the following commands:

    1. To find your <revision-name>, run the following command:

      $ oc get istiorevisions.sailoperator.io
      Sample output:
      NAME              TYPE    READY   STATUS    IN USE   VERSION   AGE
default-v1-23-0   Local   True    Healthy   True    v1.23.0   3m33s

    2. Label the namespace with the revision name to enable sidecar injection:

      $ oc label namespace httpbin istio.io/rev=default-v1-23-0

  3. Deploy a sample service named httpbin by running the following command:

    $ oc apply -n httpbin -f https://raw.githubusercontent.com/openshift-service-mesh/istio/refs/heads/master/samples/httpbin/httpbin.yaml

  4. Create a YAML file named httpbin-gw.yaml that defines an Istio Gateway resource. This resource configures gateway proxies to expose port 80 (HTTP) for the host, httpbin.example.com.

    apiVersion: networking.istio.io/v1
kind: Gateway
metadata:
  name: httpbin-gateway
  namespace: httpbin
spec:
  selector:
    istio: <gateway_name> (1)
  servers:
  - port:
      number: 80
      name: http
      protocol: HTTP
    hosts:
    - httpbin.example.com (2)
    1 Set the selector to the unique label or set of labels specified in the pod template of the gateway proxy Deployment. By default, the Istio Gateway resource configuration will apply to matching gateway pods in all namespaces.
    2 Using the hosts field, specify a list of addresses that can be used by clients when attempting to access a mesh service at the associated port.

  5. Apply the YAML file by running the following command:

    $ oc apply -f httpbin-gw.yaml

  6. Create a YAML file named httpbin-vs.yaml for a VirtualService. The VirtualService defines the rules that route traffic from the gateway proxy to the httpbin service.

    apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: httpbin
  namespace: httpbin
spec:
  hosts:
  - httpbin.example.com (1)
  gateways:
  - httpbin-gateway (2)
  http:
  - match:
    - uri:
        prefix: /status
    - uri:
        prefix: /headers
    route:
    - destination: (3)
        port:
          number: 8000
        host: httpbin
    1 Specify the hosts that the routing rules of the VirtualService will be applied to. The hosts specified must be exposed by the Istio Gateway resource the VirtualService is bound to.
    2 Bind the VirtualService to the Istio Gateway resource created in the previous step by adding the Gateway name to the list of gateways.
    3 Route matching traffic to the httpbin service deployed earlier by defining a destination that includes the host and port of the httpbin Service.

  7. Apply the YAML file by running the following command:

    $ oc apply -f httpbin-vs.yaml

  8. For verification purposes, create a namespace for a curl client by running the following command:

    $ oc create namespace curl

  9. Deploy the curl client by running the following command:

    $ oc apply -n curl -f https://raw.githubusercontent.com/openshift-service-mesh/istio/refs/heads/master/samples/curl/curl.yaml

  10. Set a CURL_POD variable with the name of the curl pod by running the following command:

    $ CURL_POD=$(oc get pods -n curl -l app=curl -o jsonpath='{.items[*].metadata.name}')

  11. Using the curl client, send a request to the /headers endpoint of the httpbin application through the ingress gateway Service resource. Set the Host header of the request to httpbin.example.com to match the host that the Istio Gateway and VirtualService resources specify. Run the following curl command to send the request:

    $ oc exec $CURL_POD -n curl -- \
  curl -s -I \
    -H Host:httpbin.example.com \
    <gateway_name>.<gateway_namespace>.svc.cluster.local/headers

  12. The response should have a 200 OK HTTP status indicating that the request was successful.

    Example output
    HTTP/1.1 200 OK
server: istio-envoy
...

  13. Send a curl request to an endpoint that does not have a corresponding URI prefix match defined in the httpbin VirtualService by running the following command:

    $ oc exec $CURL_POD -n curl -- \
  curl -s -I \
    -H Host:httpbin.example.com \
    <gateway_name>.<gateway_namespace>.svc.cluster.local/get

    The response should return a 404 Not Found status. This is expected because the /get endpoint does not have a matching URI prefix in the httpbin VirtualService resource.

    Example output
    HTTP/1.1 404 Not Found
server: istio-envoy
...

  14. Expose the gateway proxy to traffic outside the cluster by setting the Service type to LoadBalancer:

    $ oc patch service <gateway_name> -n <gateway_namespace> -p '{"spec": {"type": "LoadBalancer"}}'

    A gateway can also be exposed to traffic outside the cluster by using OpenShift Routes. For more information, see "Exposing a gateway to traffic outside the cluster using OpenShift Routes".

  15. Verify that httpbin service can be accessed from outside the cluster when using the external hostname or IP address of the gateway Service resource. Ensure that you set the INGRESS_HOST variable appropriately for the environment that your cluster is running in.

    1. If the cluster runs on AWS, set the INGRESS_HOST variable by running the following command:

      $ INGRESS_HOST=$(oc get service <gateway_name> -n <gateway_namespace> -o jsonpath='{.status.loadBalancer.ingress[0].hostname}')

    2. If the cluster runs on GCP or Azure, set the INGRESS_HOST variable by running the following command:

      $ INGRESS_HOST=$(oc get service <gateway_name> -n <gateway_namespace> -o jsonpath='{.status.loadBalancer.ingress[0].ip}')

    3. Send a curl request to the httpbin service using the host of the gateway by running the following command:

      $ curl -s -I -H Host:httpbin.example.com http://$INGRESS_HOST/headers

  16. Verify that the response has the HTTP/1.1 200 OK status, which indicates that the request was successful.

Additional resources

Istio Gateway resource API reference

VirtualService API reference

About exposing services to traffic outside a cluster

To enable traffic from outside an OpenShift cluster to access services in a mesh, you must expose a gateway proxy by either setting its Service type to LoadBalancer or by using the OpenShift Router.

Using Kubernetes load balancing to handle incoming traffic directly through the inbound gateway can reduce latency associated with data encryption. By managing encryption at the inbound gateway, you avoid the intermediate decryption and re-encryption steps within the mesh that often add latency. This approach allows mesh traffic to be encrypted and decrypted only once, which is generally more efficient.

The OpenShift Router provides a standard approach for managing ingress traffic, and you can use the router to manage certificates for all cluster ingress traffic using the same methods. However, the OpenShift Router introduces an additional hop between the inbound traffic and the mesh applications. Typically, you route the traffic by decrypting it at the router and then re-encrypting it at the service mesh ingress gateway, which introduces latency.

Exposing a gateway to traffic outside the cluster by using OpenShift Routes

You can expose a gateway to traffic outside the cluster by using OpenShift Routes. This approach provides an alternative to using Kubernetes load balancer service when you have to expose gateways to traffic outside the cluster.

Prerequisites

  • You have completed the procedure, Exposing a Service by using the Istio Gateway and VirtualService resources.

Procedure

  1. Ensure that the Service type is set to ClusterIP by running the following command:

    $ oc patch service  -n  -p '{"spec": {"type": "ClusterIP"}}'

  2. Create a YAML file named httpbin-route.yaml that defines a Route for the httpbin service.

    apiVersion: route.openshift.io/v1
kind: Route
metadata:
  name: httpbin
  namespace: <gateway_namespace>
spec:
  host: httpbin.example.com
  port:
    targetPort: http2
  to:
    kind: Service
    name: <gateway_name>
    weight: 100
  wildcardPolicy: None

  3. Apply the YAML file by running the following command:

    $ oc apply -f httpbin-route.yaml

  4. Verify that httpbin service can be accessed from outside the cluster through the ingress router. Ensure that you set the INGRESS_HOST variable appropriately for the environment that your cluster is running in.

    1. If the cluster runs on AWS, set the INGRESS_HOST variable by running the following command:

      $ INGRESS_HOST=$(oc get service router-default -n openshift-ingress -o jsonpath='{.status.loadBalancer.ingress[0].hostname}')

    2. If the cluster runs on GCP or Azure, set the INGRESS_HOST variable by running the following command:

      $ INGRESS_HOST=$(oc get service router-default -n openshift-ingress -o jsonpath='{.status.loadBalancer.ingress[0].ip}')

    3. Send a curl request to the httpbin service using the host of the ingress router by running the following command:

      $ curl -s -I -H Host:httpbin.example.com http://$INGRESS_HOST/headers

  5. Verify that the response has the HTTP/1.1 200 OK status, which indicates that the request was successful.

Additional resources