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Comparing Service Mesh and Istio

An installation of Red Hat OpenShift Service Mesh differs from upstream Istio community installations in multiple ways. The modifications to Red Hat OpenShift Service Mesh are sometimes necessary to resolve issues, provide additional features, or to handle differences when deploying on OpenShift Container Platform.

The current release of Red Hat OpenShift Service Mesh differs from the current upstream Istio community release in the following ways:

Red Hat OpenShift Service Mesh control plane

Red Hat OpenShift Service Mesh installs a multi-tenant control plane by default. You specify the projects that can access the Service Mesh, and isolate the Service Mesh from other control plane instances.

Multi-tenancy in Red Hat OpenShift Service Mesh versus cluster-wide installations

The main difference between a multi-tenant installation and a cluster-wide installation is the scope of privileges used by the control plane deployments, for example, Galley and Pilot. The components no longer use cluster-scoped Role Based Access Control (RBAC) resource ClusterRoleBinding, but rely on project-scoped RoleBinding.

Every project in the members list will have a RoleBinding for each service account associated with a control plane deployment and each control plane deployment will only watch those member projects. Each member project has a maistra.io/member-of label added to it, where the member-of value is the project containing the control plane installation.

Red Hat OpenShift Service Mesh configures each member project to ensure network access between itself, the control plane, and other member projects. The exact configuration differs depending on how OpenShift software-defined networking (SDN) is configured. See About OpenShift SDN for additional details.

If the OpenShift Container Platform cluster is configured to use the SDN plug-in:

  • NetworkPolicy: Red Hat OpenShift Service Mesh creates a NetworkPolicy resource in each member project allowing ingress to all pods from the other members and the control plane. If you remove a member from Service Mesh, this NetworkPolicy resource is deleted from the project.

    This also restricts ingress to only member projects. If ingress from non-member projects is required, you need to create a NetworkPolicy to allow that traffic through.

  • Multitenant: Red Hat OpenShift Service Mesh joins the NetNamespace for each member project to the NetNamespace of the control plane project (the equivalent of running oc adm pod-network join-projects --to control-plane-project member-project). If you remove a member from the Service Mesh, its NetNamespace is isolated from the control plane (the equivalent of running oc adm pod-network isolate-projects member-project).

  • Subnet: No additional configuration is performed.

Automatic injection

The upstream Istio community installation automatically injects the sidecar into pods within the projects you have labeled.

Red Hat OpenShift Service Mesh does not automatically inject the sidecar to any pods, but requires you to specify the sidecar.istio.io/inject annotation as illustrated in the Automatic sidecar injection section.

Istio Role Based Access Control features

Istio Role Based Access Control (RBAC) provides a mechanism you can use to control access to a service. You can identify subjects by user name or by specifying a set of properties and apply access controls accordingly.

The upstream Istio community installation includes options to perform exact header matches, match wildcards in headers, or check for a header containing a specific prefix or suffix.

Red Hat OpenShift Service Mesh extends the ability to match request headers by using a regular expression. Specify a property key of request.regex.headers with a regular expression.

Upstream Istio community matching request headers example
apiVersion: "rbac.istio.io/v1alpha1"
kind: ServiceRoleBinding
metadata:
  name: httpbin-client-binding
  namespace: httpbin
spec:
  subjects:
  - user: "cluster.local/ns/istio-system/sa/istio-ingressgateway-service-account"
    properties:
      request.headers[<header>]: "value"
Red Hat OpenShift Service Mesh matching request headers by using regular expressions
apiVersion: "rbac.istio.io/v1alpha1"
kind: ServiceRoleBinding
metadata:
  name: httpbin-client-binding
  namespace: httpbin
spec:
  subjects:
  - user: "cluster.local/ns/istio-system/sa/istio-ingressgateway-service-account"
    properties:
      request.regex.headers[<header>]: "<regular expression>"

OpenSSL

Red Hat OpenShift Service Mesh replaces BoringSSL with OpenSSL. OpenSSL is a software library that contains an open source implementation of the Secure Sockets Layer (SSL) and Transport Layer Security (TLS) protocols. The Red Hat OpenShift Service Mesh Proxy binary dynamically links the OpenSSL libraries (libssl and libcrypto) from the underlying Red Hat Enterprise Linux operating system.

The Istio Container Network Interface (CNI) plug-in

Red Hat OpenShift Service Mesh includes CNI plug-in, which provides you with an alternate way to configure application pod networking. The CNI plug-in replaces the init-container network configuration eliminating the need to grant service accounts and projects access to Security Context Constraints (SCCs) with elevated privileges.

Kiali and service mesh

Installing Kiali via the Service Mesh on OpenShift Container Platform differs from community Kiali installations in multiple ways. These modifications are sometimes necessary to resolve issues, provide additional features, or to handle differences when deploying on OpenShift Container Platform.

  • Kiali has been enabled by default.

  • Ingress has been enabled by default.

  • Updates have been made to the Kiali ConfigMap.

  • Updates have been made to the ClusterRole settings for Kiali.

  • Users should not manually edit the ConfigMap or the Kiali custom resource files as those changes might be overwritten by the Service Mesh or Kiali operators. All configuration for Kiali running on Red Hat OpenShift Service Mesh is done in the ServiceMeshControlPlane custom resource file and there are limited configuration options. Updating the operator files should be restricted to those users with cluster-admin privileges.

Jaeger and service mesh

Installing Jaeger with the Service Mesh on OpenShift Container Platform differs from community Jaeger installations in multiple ways. These modifications are sometimes necessary to resolve issues, provide additional features, or to handle differences when deploying on OpenShift Container Platform.

  • Jaeger has been enabled by default for Service Mesh.

  • Ingress has been enabled by default for Service Mesh.

  • The name for the Zipkin port name has changed to jaeger-collector-zipkin (from http)

  • Jaeger uses Elasticsearch for storage by default.

  • The community version of Istio provides a generic "tracing" route. Red Hat OpenShift Service Mesh uses a "jaeger" route that is installed by the Jaeger operator and is already protected by OAuth.

  • Red Hat OpenShift Service Mesh uses a sidecar for the Envoy proxy, and Jaeger also uses a sidecar, for the Jaeger agent. These two sidecars are configured separately and should not be confused with each other. The proxy sidecar creates spans related to the pod’s ingress and egress traffic. The agent sidecar receives the spans emitted by the application and sends them to the Jaeger Collector.