Enable Automatic Route Creation

Service Mesh OpenShift

- Thomas Jungbauer Thomas Jungbauer ( Lastmod: 2024-05-05 ) - 2 min read

Red Hat Service Mesh 1.1 allows you to enable a "Automatic Route Creation" which will take care about the routes for a specific Gateway. Instead of defining * for hosts, a list of domains can be defined. The Istio OpenShift Routing (ior) synchronizes the routes and creates them inside the Istio namespace. If a Gateway is deleted, the routes will also be removed again.

This new features makes the manual creation of the route obsolete, as it was explained here: Openshift 4 and Service Mesh 4 - Ingress with custom domain

Enable Automatic Route Creation

Before this feature can be used, it must be enabled. To do so the ServiceMeshContolPlace, typically found in the namespace istio-system must be modified. Add the line ior_enabled: true to the istio-ingressgate configuration.

...
spec:
  istio:
    gateways:
      istio-egressgateway:
        autoscaleEnabled: false
      istio-ingressgateway:
        autoscaleEnabled: false
        ior_enabled: true
...

Verify current service

Let’s check our tutorial application, if it is still working.

oc project tutorial

export GATEWAY_URL=$(oc -n istio-system get route istio-ingressgateway -o jsonpath='{.spec.host}')
curl $GATEWAY_URL/customer

customer => preference => recommendation v1 from 'f11b097f1dd0': 30

Let’s review and remove the current used Gateway. As you can see the hosts is set to '*'

oc get istio-io

oc get gateway.networking.istio.io/customer-gateway -o yaml
apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"networking.istio.io/v1alpha3","kind":"Gateway","metadata":{"annotations":{},"name":"customer-gateway","namespace":"tutorial"},"spec":{"selector":{"istio":"ingressgateway"},"servers":[{"hosts":["*"],"port":{"name":"http","number":80,"protocol":"HTTP"}}]}}
  creationTimestamp: "2020-05-13T07:52:20Z"
  generation: 1
  name: customer-gateway
  namespace: tutorial
  resourceVersion: "41370056"
  selfLink: /apis/networking.istio.io/v1alpha3/namespaces/tutorial/gateways/customer-gateway
  uid: 96e82ed9-e870-493c-941f-bfa83c892b94
spec:
  selector:
    istio: ingressgateway
  servers:
  - hosts:
    - '*'
    port:
      name: http
      number: 80
      protocol: HTTP

Create a new Gateway

First let’s remove the current Gateway

oc delete gateway.networking.istio.io/customer-gateway

Now lets create a new Gateway, but this time we define some names for the hosts section:

cat <<'EOF' > Gateway-ior.yaml
apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
  name: customer-gateway
spec:
  selector:
    istio: ingressgateway
  servers:
  - port:
      number: 80
      name: http
      protocol: HTTP
    hosts:
    - www.example.com
    - svc.example.com
EOF

oc apply -f Gateway-ior.yaml -n tutorial

When you now check the routes, 2 new routes have been added:

oc get routes -n istio-system
NAME                              HOST/PORT                                                           PATH   SERVICES               PORT    TERMINATION          WILDCARD
...
tutorial-customer-gateway-kmqrl   www.example.com                                                            istio-ingressgateway   http2                        None
tutorial-customer-gateway-ks7q7   svc.example.com                                                            istio-ingressgateway   http2                        None

To test the connectivity, you need to be sure that the hosts, used in the Gateway, are resolvable. If they are then you can access your service:

curl www.example.com/customer
customer => preference => recommendation v1 from 'f11b097f1dd0': 31

curl svc.example.com/customer
customer => preference => recommendation v1 from 'f11b097f1dd0': 32

See Also:

  • Introducing AdminNetworkPolicies –

    Classic Kubernetes/OpenShift offer a feature called NetworkPolicy that allows users to control the traffic to and from their assigned Namespace. NetworkPolicies are designed to give project owners or tenants the ability to protect their own namespace. Sometimes, however, I worked with customers where the cluster administrators or a dedicated (network) team need to enforce these policies. Since the NetworkPolicy API is namespace-scoped, it is not possible to enforce policies across namespaces. The only solution was to create custom (project) admin and edit roles, and remove the ability of creating, modifying or deleting NetworkPolicy objects. Technically, this is possible and easily done. But shifts the whole network security to cluster administrators. Luckily, this is where AdminNetworkPolicy (ANP) and BaselineAdminNetworkPolicy (BANP) comes into play.

  • Using Kustomize to post render a Helm Chart –

    Lately I came across several issues where a given Helm Chart must be modified after it has been rendered by Argo CD. Argo CD does a helm template to render a Chart. Sometimes, especially when you work with Subcharts or when a specific setting is not yet supported by the Chart, you need to modify it later …​ you need to post-render the Chart. In this very short article, I would like to demonstrate this on a real-live example I had to do. I would like to inject annotations to a Route objects, so that the certificate can be injected. This is done by the cert-utils operator. For the post-rendering the Argo CD repo pod will be extended with a sidecar container, that is watching for the repos and patches them if required.

  • Managing Certificates using GitOps approach –

    The article SSL Certificate Management for OpenShift on AWS explains how to use the Cert-Manager Operator to request and install a new SSL Certificate. This time, I would like to leverage the GitOps approach using the Helm Chart cert-manager I have prepared to deploy the Operator and order new Certificates. I will use an ACME Letsencrypt issuer with a DNS challenge. My domain is hosted at AWS Route 53. However, any other integration can be easily used.

  • Update Cluster Version using GitOps approach –

    During a GitOps journey at one point, the question arises, how to update a cluster? Nowadays it is very easy to update a cluster using CLI or WebUI, so why bother with GitOps in that case? The reason is simple: Using GitOps you can be sure that all clusters are updated to the correct, required version and the version of each cluster is also managed in Git. All you need is the channel you want to use and the desired cluster version. Optionally, you can define the exact image SHA. This might be required when you are operating in a restricted environment.

  • Multiple Sources for Applications in Argo CD –

    Argo CD or OpenShift GitOps uses Applications or ApplicationSets to define the relationship between a source (Git) and a cluster. Typically, this is a 1:1 link, which means one Application is using one source to compare the cluster status. This can be a limitation. For example, if you are working with Helm Charts and a Helm repository, you do not want to re-build (or re-release) the whole chart just because you made a small change in the values file that is packaged into the repository. You want to separate the configuration of the chart with the Helm package. The most common scenarios for multiple sources are (see: Argo CD documentation): Your organization wants to use an external/public Helm chart You want to override the Helm values with your own local values You don’t want to clone the Helm chart locally as well because that would lead to duplication and you would need to monitor it manually for upstream changes. This small article describes three different ways with a working example and tries to cover the advantages and disadvantages of each of them. They might be opinionated but some of them proved to be easier to use and manage.

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