OpenShift

Follow these instructions to prepare an OpenShift cluster for Istio.

By default, OpenShift doesn't allow containers running with user ID 0. You must enable containers running with UID 0 for Istio's service accounts:

$ oc adm policy add-scc-to-user anyuid -z istio-ingress-service-account -n istio-system
$ oc adm policy add-scc-to-user anyuid -z default -n istio-system
$ oc adm policy add-scc-to-user anyuid -z prometheus -n istio-system
$ oc adm policy add-scc-to-user anyuid -z istio-egressgateway-service-account -n istio-system
$ oc adm policy add-scc-to-user anyuid -z istio-citadel-service-account -n istio-system
$ oc adm policy add-scc-to-user anyuid -z istio-ingressgateway-service-account -n istio-system
$ oc adm policy add-scc-to-user anyuid -z istio-cleanup-old-ca-service-account -n istio-system
$ oc adm policy add-scc-to-user anyuid -z istio-mixer-post-install-account -n istio-system
$ oc adm policy add-scc-to-user anyuid -z istio-mixer-service-account -n istio-system
$ oc adm policy add-scc-to-user anyuid -z istio-pilot-service-account -n istio-system
$ oc adm policy add-scc-to-user anyuid -z istio-sidecar-injector-service-account -n istio-system
$ oc adm policy add-scc-to-user anyuid -z istio-galley-service-account -n istio-system
$ oc adm policy add-scc-to-user anyuid -z istio-security-post-install-account -n istio-system

The list above accounts for the default Istio service accounts. If you enabled other Istio services, like Grafana for example, you need to enable its service account with a similar command.

A service account that runs application pods needs privileged security context constraints as part of sidecar injection:

$ oc adm policy add-scc-to-user privileged -z default -n <target-namespace>

Install Istio using the CNI instructions.

After installation is complete, expose an OpenShift route for the ingress gateway.

$ oc expose svc/istio-ingressgateway --port=80

Automatic Injection

Webhook and certificate signing requests support must be enabled for automatic injection to work. Modify the master configuration file on the master node for the cluster as follows.

In the same directory as the master configuration file, create a file named master-config.patch with the following contents:

admissionConfig:
  pluginConfig:
    MutatingAdmissionWebhook:
      configuration:
        apiVersion: apiserver.config.k8s.io/v1alpha1
        kubeConfigFile: /dev/null
        kind: WebhookAdmission
    ValidatingAdmissionWebhook:
      configuration:
        apiVersion: apiserver.config.k8s.io/v1alpha1
        kubeConfigFile: /dev/null
        kind: WebhookAdmission

In the same directory, execute:

$ cp -p master-config.yaml master-config.yaml.prepatch
$ oc ex config patch master-config.yaml.prepatch -p "$(cat master-config.patch)" > master-config.yaml
$ master-restart api
$ master-restart controllers

Bookinfo

The Istio sidecar injected into each pod runs with user ID 1337, which is not allowed by default in OpenShift. To allow this user ID to be used, execute the following commands. Replace -n bookinfo with the appropriate namespace.

$ oc adm policy add-scc-to-group privileged system:serviceaccounts -n bookinfo
$ oc adm policy add-scc-to-group anyuid system:serviceaccounts -n bookinfo

When removing the Bookinfo application, remove the permissions as follows.

$ oc adm policy remove-scc-from-group privileged system:serviceaccounts -n bookinfo
$ oc adm policy remove-scc-from-group anyuid system:serviceaccounts -n bookinfo