Ingress with custom domain

Service Mesh OpenShift

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

Since Service Mesh 1.1, there is a better way to achieve the following. Especially the manual creation of the route is not required anymore. Check the following article to Enable Automatic Route Creation.

Often the question is how to get traffic into the Service Mesh when using a custom domains. Part 4 our our tutorials series OpenShift 4 and Service Mesh will use a dummy domain "hello-world.com" and explains the required settings which must be done.

Modify Gateway and VirtualService

Issue #3 explains how to get ingress traffic into the Service Mesh, by defining the Gateway and the VirtualService. We are currently using the default ingress route defined in the istio_system project.
But what if a custom domain shall be used?
In such case another route must be defined in the istio-system project and small configuration changes must be applied.

  1. First lets create a slightly modified Gateway.yaml:

    apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
  name: ingress-gateway-exampleapp
spec:
  selector:
    istio: ingressgateway # use istio default controller
  servers:
  - port:
      number: 80
      name: http
      protocol: HTTP
    hosts:
    - "hello-world.com" (1)
    1add you custom domain here

    The only difference is at the hosts which was changed from '*' to 'hello-world.com'

  2. As second change, the VirtualService must be modified as well with the custom domain:

    VirtualService.yaml:

    apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: ingress-gateway-exampleapp
spec:
  hosts:
  - "hello-world.com" (1)
  gateways:
  - ingress-gateway-exampleapp
  http:
  - match:
    - uri:
        exact: /
    route:
    - destination:
        host: customer
        port:
          number: 8080
    1add you custom domain here

  3. Replace current objects in OpenShift:

    oc replace -f Gateway.yaml -n tutorial
oc replace -f VirtualService.yaml -n tutorial

  4. Create a new route under the project istio-system:

    apiVersion: route.openshift.io/v1
kind: Route
metadata:
  name: hello-world.com (1)
  namespace: istio-system (2)
spec:
  host: hello-world.com (3)
  to:
    kind: Service
    name: istio-ingressgateway (4)
  port:
    targetPort: 8080
    1add you custom domain here
    2the route must be created at istio-system
    3add you custom domain here
    4this is the service as it was created by the operator

OPTIONAL: Add custom domain to local hosts file

The custom domain hello-world.com must be resolvable somehow, pointing to the ingress router of OpenShift. This can be done, by adding the domain into the local hosts file (with all limitations this brings with it)

# Get IP address of:
oc -n istio-system get route istio-ingressgateway
echo "x.x.x.x hello-world.com" >> /etc/hosts

Create some example traffic

We will reuse the script of Issue #3 to simulate traffic. Since we changed the domain, the connection will go to hello-world.com

sh run-check.sh 1000 hello-world.com

This will send 1000 requests to our application:

# 0: customer => preference => recommendation v1 from 'f11b097f1dd0': 6626
# 1: customer => preference => recommendation v1 from 'f11b097f1dd0': 6627
# 2: customer => preference => recommendation v1 from 'f11b097f1dd0': 6628
# 3: customer => preference => recommendation v1 from 'f11b097f1dd0': 6629
# 4: customer => preference => recommendation v1 from 'f11b097f1dd0': 6630
# 5: customer => preference => recommendation v1 from 'f11b097f1dd0': 6631
...

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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