The istio/operator repo is part of istio/istio from 1.5 onwards. You can contribute by picking an unassigned open issue, creating a bug or feature request, or just coming to the weekly Environments Working Group meeting to share your ideas.
This document is an overview of how the operator works from a user perspective. For more details about the design and architecture and a code overview, see ARCHITECTURE.md.
The operator uses the IstioOperator API, which has three main components:
- MeshConfig for runtime config consumed directly by Istio control plane components.
- Component configuration API, for managing K8s settings like resources, auto scaling, pod disruption budgets and others defined in the KubernetesResourceSpec for Istio core and addon components.
- The legacy Helm installation API for backwards compatibility.
Some parameters will temporarily exist both the component configuration and legacy Helm APIs - for example, K8s resources. However, the Istio community recommends using the first API as it is more consistent, is validated, and will naturally follow the graduation process for APIs while the same parameters in the configuration API are planned for deprecation.
Profiles, are provided as a starting point for an Istio install and can be customized by creating customization overlay files or passing parameters through the --set flag. For example, to select the minimal profile:
# minimal.yaml apiVersion: install.istio.io/v1alpha1 kind: IstioOperator spec: profile: minimal
If you don't specify a configuration profile, Istio is installed using the
default configuration profile. All
profiles listed in istio.io are available by default, or
profile: can point to a local file path to reference a custom
profile base to use as a starting point for customization. See the API reference
Developer quick start
The quick start describes how to install and use the operator
mesh CLI command and/or controller.
To build the operator CLI, simply:
Ensure the created binary is in your PATH to run the examples below.
Controller (in cluster)
Building a custom controller requires a Dockerhub (or similar) account. To build using the container based build:
HUB=docker.io/<your-account> TAG=latest make docker.operator
This builds the controller binary and docker file, and pushes the image to the specified hub with the
Once the images are pushed, configure kubectl to point to your cluster and install the controller.
Install the controller manifest:
istioctl operator init --hub docker.io/<your-account> --tag latest kubectl create ns istio-system kubectl apply -f operator/samples/default-install.yaml
This installs the controller into the cluster in the istio-operator namespace. The controller in turns installs the Istio control plane into the istio-system namespace by default.
Controller (running locally)
Set env $WATCH_NAMESPACE (default value is "istio-system") and $LEADER_ELECTION_NAMESPACE (default value is "istio-operator")
LEADER_ELECTION_NAMESPACEif they are not created yet.
kubectl create ns $WATCH_NAMESPACE --dry-run -o yaml | kubectl apply -f - kubectl create ns $LEADER_ELECTION_NAMESPACE --dry-run -o yaml | kubectl apply -f -
- From the istio repo root directory, run
go run ./operator/cmd/operator/*.go server
To use Remote debugging with IntelliJ, replace above step 2 with following:
dlv debug --headless --listen=:2345 --api-version=2 -- server.
In IntelliJ, create a new Go Remote debug configuration with default settings.
Start debugging process and verify it is working. For example, try adding a breakpoint at Reconcile logic and apply a new CR.
Relationship between the CLI and controller
The CLI and controller share the same API and codebase for generating manifests from the API. You can think of the
controller as the CLI command
istioctl install running in a loop in a pod in the cluster and using the config
from the in-cluster IstioOperator custom resource (CR).
There are two major differences:
- The controller does not accept any dynamic user config through flags. All user interaction is through the IstioOperator CR.
- The controller has additional logic that mirrors istioctl commands like upgrade, but is driven from the declarative API rather than command line.
Quick tour of CLI commands
istioctl command supports the following flags:
dry-run: console output only, nothing applied to cluster or written to files.
verbose: display entire manifest contents and other debug info (default is false).
set: select profile or override profile defaults
Basic default manifest
The following command generates a manifest with the compiled-in
default profile and charts:
istioctl manifest generate
You can see these sources for the compiled-in profiles and charts in the repo under
manifests/. These profiles and charts are also included in the Istio release tar.
Output to dirs
The output of the manifest is concatenated into a single file. To generate a directory hierarchy with subdirectory levels representing a child dependency, use the following command:
istioctl manifest generate -o istio_manifests
Use depth first search to traverse the created directory hierarchy when applying your YAML files. This is needed for correct sequencing of dependencies. Child manifest directories must wait for their parent directory to be fully applied, but not their sibling manifest directories.
Just apply it for me
The following command generates the manifests and applies them in the correct dependency order, waiting for the dependencies to have the needed CRDs available:
Review the values of a configuration profile
The following commands show the values of a configuration profile:
# show available profiles istioctl profile list # show the values in demo profile istioctl profile dump demo # show the values after a customization file is applied istioctl profile dump -f samples/pilot-k8s.yaml # show differences between the default and demo profiles istioctl profile dump default > 1.yaml istioctl profile dump demo > 2.yaml istioctl profile diff 1.yaml 2.yaml # show the differences in the generated manifests between the default profile and a customized install istioctl manifest generate > 1.yaml istioctl manifest generate -f samples/pilot-k8s.yaml > 2.yaml istioctl manifest diff 1.yam1 2.yaml
The profile dump sub-command supports a couple of useful flags:
config-path: select the root for the configuration subtree you want to see e.g. just show Pilot:
istioctl profile dump --config-path components.pilot
filename: set parameters in the configuration file before dumping the resulting profile e.g. show the pilot k8s overlay settings:
istioctl profile dump --filename samples/pilot-k8s.yaml
Select a specific configuration profile
The simplest customization is to select a profile different to
minimal. See manifests/profiles/minimal.yaml:
# minimal-install.yaml apiVersion: install.istio.io/v1alpha1 kind: IstioOperator spec: profile: minimal
istioctl to generate the manifests for the new configuration profile:
istioctl manifest generate -f manifests/profiles/minimal.yaml
After running the command, the Helm charts are rendered using
--set option can be used to override settings within the profile.
For example, to enable auto mTLS, use
istioctl manifest generate --set values.global.mtls.auto=true --set values.global.controlPlaneSecurityEnabled=true
To override a setting that includes dots, escape them with a backslash (). Your shell may require enclosing quotes.
istioctl manifest generate --set "values.sidecarInjectorWebhook.injectedAnnotations.container\.apparmor\.security\.beta\.kubernetes\.io/istio-proxy=runtime/default"
To override a setting that is part of a list, use brackets.
istioctl manifest generate --set values.gateways.istio-ingressgateway.enabled=false \ --set values.gateways.istio-egressgateway.enabled=true \ --set 'values.gateways.istio-egressgateway.secretVolumes.name'=egressgateway-certs \ --set 'values.gateways.istio-egressgateway.secretVolumes.secretName'=istio-egressgateway-certs \ --set 'values.gateways.istio-egressgateway.secretVolumes.mountPath'=/etc/istio/egressgateway-certs
Install from file path
The compiled in charts and profiles are used by default, but you can specify a file path, for example:
apiVersion: install.istio.io/v1alpha1 kind: IstioOperator spec: profile: /usr/home/bob/go/src/github.com/ostromart/istio-installer/data/profiles/default.yaml installPackagePath: /usr/home/bob/go/src/github.com/ostromart/istio-installer/data/charts/
You can mix and match these approaches. For example, you can use a compiled-in configuration profile with charts in your local file system.
Check diffs of manifests
The following command takes two manifests and output the differences in a readable way. It can be used to compare between the manifests generated by operator API and helm directly:
istioctl manifest diff ./out/helm-template/manifest.yaml ./out/mesh-manifest/manifest.yaml
New API customization
The new platform level installation API defines install time parameters like component and enablement and namespace, and K8s settings like resources, HPA spec etc. in a structured way. The simplest customization is to turn components on and off. For example, to turn on cni (samples/cni-on.yaml:
apiVersion: install.istio.io/v1alpha1 kind: IstioOperator spec: components: cni: enabled: true
The operator validates the configuration and automatically detects syntax errors. If you are using Helm values that are incompatible, the schema validation used in the operator may reject input that is valid for Helm. Each Istio component has K8s settings, and these can be overridden from the defaults using official K8s APIs rather than Istio defined schemas (samples/pilot-k8s.yaml):
apiVersion: install.istio.io/v1alpha1 kind: IstioOperator spec: components: pilot: k8s: resources: requests: cpu: 1000m # override from default 500m memory: 4096Mi # ... default 2048Mi hpaSpec: maxReplicas: 10 # ... default 5 minReplicas: 2 # ... default 1 nodeSelector: # ... default empty master: "true" tolerations: # ... default empty - key: dedicated operator: Exists effect: NoSchedule - key: CriticalAddonsOnly operator: Exists
The K8s settings are defined in detail in the operator API. The settings are the same for all components, so a user can configure pilot K8s settings in exactly the same, consistent way as galley settings. Supported K8s settings currently include:
- readiness probes
- replica count
- pod annotations
- container environment variables
- priority class name
- node selector
- affinity and anti-affinity
- deployment strategy
- service annotations
- service spec
- pod securityContext
All of these K8s settings use the K8s API definitions, so K8s documentation can be used for reference. All K8s overlay values are also validated in the operator.
Customizing the old values.yaml API
The new platform install API above deals with K8s level settings. The remaining values.yaml parameters deal with Istio control plane operation rather than installation. For the time being, the operator just passes these through to the Helm charts unmodified (but validated through a schema). Values.yaml settings are overridden the same way as the new API, though a customized CR overlaid over default values for the selected profile. Here's an example of overriding some global level default values (samples/values-global.yaml):
apiVersion: install.istio.io/v1alpha1 kind: IstioOperator spec: profile: sds values: global: logging: level: "default:warning" # override from info
Values overrides can also be specified for a particular component (samples/values-pilot.yaml):
apiVersion: install.istio.io/v1alpha1 kind: IstioOperator spec: values: pilot: traceSampling: 0.1 # override from 1.0
Advanced K8s resource overlays
Advanced users may occasionally have the need to customize parameters (like container command line flags) which are not exposed through either of the installation or configuration APIs described in this document. For such cases, it's possible to overlay the generated K8s resources before they are applied with user-defined overlays. For example, to override some container level values in the Pilot container (samples/pilot-advanced-override.yaml):
apiVersion: install.istio.io/v1alpha1 kind: IstioOperator spec: components: pilot: k8s: overlays: - kind: Deployment name: istio-pilot patches: - path: spec.template.spec.containers.[name:discovery].args.[30m] value: "60m" # OVERRIDDEN - path: spec.template.spec.containers.[name:discovery].ports.[containerPort:8080].containerPort value: 8090 # OVERRIDDEN - path: 'spec.template.spec.volumes' #push to the list value: configMap: name: my-config-map name: my-volume-name - path: 'spec.template.spec.containers.volumeMounts' value: mountPath: /mnt/path1 name: my-volume-name - kind: Service name: istio-pilot patches: - path: spec.ports.[name:grpc-xds].port value: 15099 # OVERRIDDEN
The user-defined overlay uses a path spec that includes the ability to select list items by key. In the example above, the container with the key-value "name: discovery" is selected from the list of containers, and the command line parameter with value "30m" is selected to be modified. The advanced overlay capability is described in more detail in the spec.
Interaction with controller
The controller shares the same API as the operator CLI, so it's possible to install any of the above examples as a CR
in the cluster in the istio-system namespace and the controller will react to it with the same outcome as running
istioctl install -f <path-to-custom-resource-file>.
Package mesh contains types and functions.
|Package mesh contains types and functions.|
Package v1alpha1 contains API Schema definitions for the istio v1alpha1 API group Package v1alpha1 contains API Schema definitions for the istio v1alpha1 API group +k8s:deepcopy-gen=package,register +groupName=install.istio.io
|Package v1alpha1 contains API Schema definitions for the istio v1alpha1 API group Package v1alpha1 contains API Schema definitions for the istio v1alpha1 API group +k8s:deepcopy-gen=package,register +groupName=install.istio.io|
Package component defines an in-memory representation of IstioOperator.<Feature>.<Component>.
|Package component defines an in-memory representation of IstioOperator.<Feature>.<Component>.|
Package metrics defines metrics and monitoring functionality used throughout operator.
|Package metrics defines metrics and monitoring functionality used throughout operator.|
Package manifest provides functions for going between in-memory k8s objects (unstructured.Unstructured) and their JSON or YAML representations.
|Package manifest provides functions for going between in-memory k8s objects (unstructured.Unstructured) and their JSON or YAML representations.|
Package patch implements a simple patching mechanism for k8s resources.
|Package patch implements a simple patching mechanism for k8s resources.|
struct.go contains functions for traversing and modifying trees of Go structs.
|struct.go contains functions for traversing and modifying trees of Go structs.|
Package translate defines translations from installer proto to values.yaml.
|Package translate defines translations from installer proto to values.yaml.|