Overview

Istio is a service mesh for Kubernetes. A control plane (istiod) configures Envoy sidecar proxies (or, in ambient mode, per-node ztunnel plus optional waypoint proxies) so that routing, retries, mutual TLS, access policy and telemetry are handled outside application code. This skill covers installation with istioctl, the core resources (VirtualService, DestinationRule, Gateway API, PeerAuthentication, AuthorizationPolicy, Telemetry) and debugging.

Instructions

Install

Prefer a package manager, or download the release archive and verify its checksum. Do not pipe the downloadIstio script into a shell.

bash

brew install istioctl            # macOS / Linuxbrew

# or: pinned release archive with checksum verification (Linux x86-64)
ISTIO_VERSION=1.31.1
BASE=https://github.com/istio/istio/releases/download/$ISTIO_VERSION
curl -fsSLO $BASE/istioctl-$ISTIO_VERSION-linux-amd64.tar.gz
curl -fsSLO $BASE/istioctl-$ISTIO_VERSION-linux-amd64.tar.gz.sha256
sha256sum -c istioctl-$ISTIO_VERSION-linux-amd64.tar.gz.sha256
tar xzf istioctl-$ISTIO_VERSION-linux-amd64.tar.gz && sudo install istioctl /usr/local/bin/

istioctl x precheck                              # check the cluster first
istioctl install --set profile=default -y        # or profile=demo for evaluation, profile=ambient for ambient mode
kubectl label namespace shop istio-injection=enabled   # sidecar mode: restart pods afterwards
istioctl analyze --all-namespaces                # lint configuration

istioctl verify-install no longer exists; use istioctl analyze and kubectl -n istio-system get pods. istioctl upgrade is just an alias of istioctl install. Do not skip more than two minor versions per upgrade; for production prefer a canary control plane with --set revision=1-31-1 and istioctl tag set. For ambient mode label namespaces with istio.io/dataplane-mode=ambient instead.

IstioOperator options

yaml

# istio-config.yaml: apply with `istioctl install -f istio-config.yaml`
apiVersion: install.istio.io/v1alpha1
kind: IstioOperator
spec:
  profile: default
  meshConfig:
    accessLogFile: /dev/stdout
    extensionProviders:
      - name: zipkin
        zipkin:
          service: zipkin.observability.svc.cluster.local
          port: 9411
  components:
    ingressGateways:
      - name: istio-ingressgateway
        enabled: true
        k8s:
          hpaSpec: { minReplicas: 2, maxReplicas: 5 }

Tracing is switched on per mesh, namespace or workload with the Telemetry API, not with meshConfig.defaultConfig.tracing:

yaml

apiVersion: telemetry.istio.io/v1
kind: Telemetry
metadata:
  name: mesh-default
  namespace: istio-system
spec:
  tracing:
    - providers:
        - name: zipkin
      randomSamplingPercentage: 5.0

Traffic management

yaml

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: web-app
  namespace: shop
spec:
  hosts: [web-app]
  http:
    - match:
        - headers:
            x-canary:
              exact: "true"
      route:
        - destination: { host: web-app, subset: canary }
    - route:
        - destination: { host: web-app, subset: stable }
          weight: 90
        - destination: { host: web-app, subset: canary }
          weight: 10
      timeout: 10s
      retries:
        attempts: 3
        perTryTimeout: 3s
        retryOn: 5xx,reset,connect-failure
---
apiVersion: networking.istio.io/v1
kind: DestinationRule
metadata:
  name: web-app
  namespace: shop
spec:
  host: web-app
  trafficPolicy:
    connectionPool:
      tcp: { maxConnections: 100 }
      http: { http1MaxPendingRequests: 100, http2MaxRequests: 1000 }
    outlierDetection:
      consecutive5xxErrors: 5
      interval: 30s
      baseEjectionTime: 30s
      maxEjectionPercent: 50
  subsets:
    - name: stable
      labels: { version: v1 }
    - name: canary
      labels: { version: v2 }

Ingress with the Kubernetes Gateway API (recommended)

Gateway API CRDs are not installed on most clusters. At the time of writing the Istio docs install v1.6.0:

bash

kubectl kustomize "github.com/kubernetes-sigs/gateway-api/config/crd?ref=v1.6.0" | kubectl apply -f -

yaml

apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: shop-gateway
  namespace: istio-ingress
spec:
  gatewayClassName: istio
  listeners:
    - name: https
      hostname: shop.acme-store.dev
      port: 443
      protocol: HTTPS
      tls:
        mode: Terminate
        certificateRefs:
          - name: shop-tls-cert
      allowedRoutes:
        namespaces: { from: All }
---
apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: shop
  namespace: shop
spec:
  parentRefs:
    - name: shop-gateway
      namespace: istio-ingress
  hostnames: ["shop.acme-store.dev"]
  rules:
    - matches:
        - path: { type: PathPrefix, value: /api }
      backendRefs:
        - name: api-service
          port: 8080
    - backendRefs:
        - name: frontend
          port: 80

Istio creates the gateway Deployment and Service automatically for a Gateway with gatewayClassName: istio. The older networking.istio.io Gateway (with selector: istio: ingressgateway and a VirtualService bound through gateways:) is still supported if you run the istio-ingressgateway component.

Security

yaml

apiVersion: security.istio.io/v1
kind: PeerAuthentication
metadata:
  name: default
  namespace: istio-system   # root namespace = mesh-wide
spec:
  mtls:
    mode: STRICT
---
apiVersion: security.istio.io/v1
kind: AuthorizationPolicy
metadata:
  name: api-access
  namespace: shop
spec:
  selector:
    matchLabels:
      app: api-service
  action: ALLOW
  rules:
    - from:
        - source:
            principals: ["cluster.local/ns/shop/sa/frontend"]
      to:
        - operation:
            methods: ["GET", "POST"]
            paths: ["/api/*"]

Fault injection

yaml

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: api-fault-test
  namespace: shop
spec:
  hosts: [api-service]
  http:
    - fault:
        delay: { percentage: { value: 10 }, fixedDelay: 5s }
        abort: { percentage: { value: 5 }, httpStatus: 503 }
      route:
        - destination: { host: api-service }

Debugging

bash

istioctl proxy-status                          # is every proxy synced with istiod?
istioctl proxy-config routes deploy/web-app -n shop
istioctl proxy-config clusters deploy/web-app -n shop
istioctl analyze -n shop
istioctl dashboard kiali                       # needs the Kiali addon installed

Examples

Example 1: Canary release of web-app at 10%

User request: "Send 10% of traffic for web-app to v2 and let my QA header always hit v2."

Label the Deployments version: v1 and version: v2, apply the VirtualService and DestinationRule above, then check with istioctl analyze -n shop (expected: No validation issues found) and istioctl proxy-config routes deploy/web-app -n shop. Requests with x-canary: true go to v2; others split 90/10. Raise the weight in steps and watch 5xx rates in Kiali or Prometheus before moving on.

Example 2: Turn on strict mTLS safely

User request: "Make all service-to-service traffic encrypted."

Inject sidecars (or enroll namespaces in ambient mode) everywhere first, apply a PeerAuthentication with mode: PERMISSIVE in shop, confirm in Kiali that every edge shows a padlock, then change to STRICT mesh-wide as above. Result: plaintext calls from non-mesh pods now fail with connection resets, which is the intended signal to fix them.

Guidelines

Sidecars only appear on pods created after labeling a namespace; run kubectl rollout restart deployment -n shop.
Keep the istioctl version within one minor version of the control plane and upgrade one minor at a time.
Do not apply STRICT mTLS or a deny-all AuthorizationPolicy before checking every caller is in the mesh; roll out in PERMISSIVE and ALLOW first.
v1beta1/v1alpha3 networking and security APIs are still accepted, but new manifests should use v1.
Run istioctl analyze before every apply; most misconfigurations (wrong host, missing subset) are caught there.
Sampling 100% of traces is for demos; production needs about 1-5%.
Never hard-code TLS keys in manifests: use Kubernetes Secrets (credentialName/certificateRefs).
A mesh adds CPU, memory and latency per pod; do not use it for a handful of services that only need an ingress controller.

Istio

Validation

Prove Istio on your task

Getting Started

Example Prompts

Documentation

Overview

Instructions

Install

IstioOperator options

Traffic management

Ingress with the Kubernetes Gateway API (recommended)

Security

Fault injection

Debugging

Examples

Example 1: Canary release of web-app at 10%

Example 2: Turn on strict mTLS safely

Guidelines

Information

Use Cases

Related Skills