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Maistra Istio Operator

This project is an operator that can be used to manage the installation of an Istio control plane.

Installation

To install Red Hat OpenShift Service Mesh, first install the required Operators on OpenShift Container Platform and then create a ServiceMeshControlPlane resource to deploy the control plane. If you are a user, refer to the documentation for how to install and configure Istio Operator on Red Hat OpenShift Service Mesh. If you are a developer, refer DEVEL.md for more advance configurations.

API documentation

The API reference documentation is available in the maistra/api repository.

Multitenancy

The operator installs a control plane configured for multitenancy. This installation reduces the scope of the control plane to only those projects/namespaces listed in a ServiceMeshMemberRoll. After installing the control plane, create/update a ServiceMeshMemberRoll resource with the project/namespaces you wish to be part of the mesh. The name of the ServiceMeshMemberRoll resource must be named default. The operator will configure the control plane to watch/manage pods in those projects/namespaces and will configure the project/namespaces to work with the control plane. (Note, auto-injection only occurs after the project/namespace has become a member of the mesh.)

ServiceMeshMemberRoll

A ServiceMeshMemberRoll is used to specify which projects/namespaces should be part of a service mesh installation. It has a single field in it's spec, which is a list of members, for example:

apiVersion: maistra.io/v1
kind: ServiceMeshMemberRoll
metadata:
  # name must be default
  name: default
spec:
  members:
  # a list of projects/namespaces that should be joined into the service mesh
  # for example, the bookinfo project/namespace
  - bookinfo

Customizing the Installation

The installation is easily customizable by modifying the .spec.istio section of the ServiceMeshControlPlane resource. If you are familiar with the Helm based installation, all of those settings are exposed through the operator.

The following sections describe common types of customizations.

Custom Images

The image registry from which the Istio control plane images are pulled may be changed by adding a global hub value to the ServiceMeshControlPlane specification. The default tag used for the images may be changed in a similar fashion. For example:

apiVersion: maistra.io/v1
kind: ServiceMeshControlPlane
metadata:
  name: full-install
spec:
  istio:
    global:
      hub: my-private-registry.com/custom-namespace
      tag: 1.2.0-dev

  ...

Image Pull Secrets

If access to the registry providing the Istio images is secure, you may add your access token settings. This will add imagePullSecrets to the appropriate ServiceAccount resources. For example:

apiVersion: maistra.io/v1
kind: ServiceMeshControlPlane
metadata:
  name: full-install
spec:
  istio:
    global:
      imagePullSecrets:
      - MyPullSecret
      - AnotherPullSecret

  ...

Resource Limits

If you will be installing into an instance that is resource constrained, you most likely will need to modify the resource requirements used by default. Resource requirements can be set by default in .spec.istio.global.defaultResources. For example:

apiVersion: maistra.io/v1
kind: ServiceMeshControlPlane
metadata:
  name: full-install
spec:
  istio:
    global:
      defaultResources:
        requests:
          cpu: 10m
          memory: 128Mi

  ...

Component Customizations

Component specific customizations may be made by modifying the appropriate setting under the component key (e.g. .spec.tracing). Many of the global customizations described above may also be applied to specific components. Some examples:

Customize resources (e.g. proxy, mixer):

apiVersion: maistra.io/v1
kind: ServiceMeshControlPlane
metadata:
  name: full-install
spec:
  istio:
    global:
      proxy:
        resources:
          requests:
            cpu: 10m
            memory: 128Mi
    mixer:
      telemetry:
        resources:
          requests:
            cpu: 10m
            memory: 128Mi

  ...

Customize component image (e.g. Kiali):

apiVersion: maistra.io/v1
kind: ServiceMeshControlPlane
metadata:
  name: full-install
spec:
  istio:
    kiali:
      hub: kiali
      tag: v1.0.0

  ...

Developing the Istio Operator

You'll find instructions on how to build and run the Operator locally in DEVEL.md.

Architecture

This operator provides a wrapper around the helm charts used when installing Istio via helm template or helm install. As such, the custom resource used to define the features of the control plane maps directly to a values.yaml file, the root of which is located in the resource's .spec.istio field. See examples of a minimal installation, full installation, a full installation with auth.

Modifications for Maistra

Aside from embedding all installation logic into the operator (e.g. removing create-custom-resources.yaml templates), the the changes made to the base Istio charts can be found below. For a specific list of all modifications, see patch-charts.sh.

Component Modifications

General

  • GODEBUG environment variable settings have been removed from all templates.
  • A maistra-version label has been added to all resources.
  • The istio-multi ServiceAccount and ClusterRoleBinding have been removed, as well as the istio-reader ClusterRole.
  • All Ingress resources have been converted to OpenShift Route resources.

Galley

  • A named targetPort has been added to the Galley Service.
  • The Galley webhook port has been moved from 443 to 8443.
  • The Galley health file has been moved to /tmp/heath (from /health)
  • The --validation-port option has been added to the Galley.

Sidecar Injector

  • Sidecar proxy init containers have been configured as privileged, regardless of global.proxy.privileged setting.
  • The opt-out mechanism for injection has been modified when sidecarInjectorWebhook.enableNamespacesByDefault is enabled. Namespaces now opt-out by adding an maistra.io/ignore-namespace label to the namespace.
  • A named targetPort has been added to the Sidecar Injector Service.
  • The Sidecar Injector webhook port has been moved from 443 to 8443.

Gateways

  • A Route has been added for the istio-ingressgateway gateway.
  • The istio-egressgateway gateway has been enabled by default.

Prometheus

  • The Prometheus init container has been modified to use the following image, docker.io/prom/prometheus:v2.3.1.

Grafana

  • Has been enabled by default.
  • Ingress has been enabled by default.
  • A ServiceAccount has been added for Grafana.

Tracing

  • Has been enabled by default.
  • Ingress has been enabled by default.
  • The hub value for the Jaeger images has changed to jaegertracing (from docker.io/jaegertracing).
  • The tag used for the Jaeger images has been updated to 1.11.
  • The name for the Zipkin port name has changed to jaeger-collector-zipkin (from http)
  • Jaeger uses Elasticsearch for storage.

Kiali

  • Has been enabled by default.
  • Ingress has been enabled by default.
  • The hub value for the Kiali image has changed to kiali (from docker.io/kiali).
  • The tag used for the Kiali image has been updated to v1.0.0.
  • A Kiali CR is now created (for the Kiali Operator) as opposed to individual Kiali resources like ConfigMap, Deployment, etc.
  • The auth strategy is "openshift".

Known Issues

The following are known issues that need to be addressed:

  • Istio CustomResourceDefinition resources are not removed during uninstall.
  • Updates have not been tested (e.g. modifying a ServiceMeshControlPlane resource to enable/disable a component).
  • Uninstall is a little sloppy (i.e. resources are just deleted, and not in an intelligent fashion).
  • Reconciliation is only performed on the ServiceMeshControlPlane resource (i.e. the operator is not watching installed resources, e.g. galley Deployment). This means users may modify those resources and the operator will not revert them (unless the ServiceMeshControlPlane resource is modified).
  • Rollout may hang if configuration changes made to the istio-operator deployment. (I believe this has to do with leader election, where the new deployment fails to become ready until the prior one is terminated.)