About gateway injection

Gateway injection utilizes the same mechanism as sidecar injection to deploy the Envoy proxy into gateway pods. To deploy a gateway:

Create a Kubernetes Deployment and a corresponding Service in a namespace visible to the Istio control plane.
Annotate and label the deployment so the Istio control plane injects an Envoy proxy configured as a gateway.
Apply Istio's Gateway and VirtualService resources to control ingress or egress traffic.

Linux Kernel Compatibility Notice

For nodes running Linux kernel versions earlier than 4.11 (e.g., CentOS 7), additional configuration is required prior to gateway installation.

INFO

Skip this section if your kernel version is 4.11 or later.

Prerequisites

Install jq locally to process JSON in these steps.

Procedure

Create a YAML file named gateway-injection-template.txt that contains the default injection template for gateways.

Click to expand

gateway-injection-template.txt

{{- $containers := list }}
{{- range $index, $container := .Spec.Containers }}{{ if not (eq $container.Name "istio-proxy") }}{{ $containers = append $containers $container.Name }}{{end}}{{- end}}
metadata:
  labels:
    service.istio.io/canonical-name: {{ index .ObjectMeta.Labels `service.istio.io/canonical-name` | default (index .ObjectMeta.Labels `app.kubernetes.io/name`) | default (index .ObjectMeta.Labels `app`) | default .DeploymentMeta.Name  | quote }}
    service.istio.io/canonical-revision: {{ index .ObjectMeta.Labels `service.istio.io/canonical-revision` | default (index .ObjectMeta.Labels `app.kubernetes.io/version`) | default (index .ObjectMeta.Labels `version`) | default "latest"  | quote }}
  annotations:
    istio.io/rev: {{ .Revision | default "default" | quote }}
    {{- if ge (len $containers) 1 }}
    {{- if not (isset .ObjectMeta.Annotations `kubectl.kubernetes.io/default-logs-container`) }}
    kubectl.kubernetes.io/default-logs-container: "{{ index $containers 0 }}"
    {{- end }}
    {{- if not (isset .ObjectMeta.Annotations `kubectl.kubernetes.io/default-container`) }}
    kubectl.kubernetes.io/default-container: "{{ index $containers 0 }}"
    {{- end }}
    {{- end }}
spec:
  securityContext:
  {{- if .Values.gateways.securityContext }}
    {{- toYaml .Values.gateways.securityContext | nindent 4 }}
  {{- else }}
    sysctls: []  
    capabilities:
      add: [CAP_NET_BIND_SERVICE]  
  {{- end }}
  containers:
  - name: istio-proxy
  {{- if contains "/" (annotation .ObjectMeta `sidecar.istio.io/proxyImage` .Values.global.proxy.image) }}
    image: "{{ annotation .ObjectMeta `sidecar.istio.io/proxyImage` .Values.global.proxy.image }}"
  {{- else }}
    image: "{{ .ProxyImage }}"
  {{- end }}
    ports:
    - containerPort: 15090
      protocol: TCP
      name: http-envoy-prom
    args:
    - proxy
    - router
    - --domain
    - $(POD_NAMESPACE).svc.{{ .Values.global.proxy.clusterDomain }}
    - --proxyLogLevel={{ annotation .ObjectMeta `sidecar.istio.io/logLevel` .Values.global.proxy.logLevel }}
    - --proxyComponentLogLevel={{ annotation .ObjectMeta `sidecar.istio.io/componentLogLevel` .Values.global.proxy.componentLogLevel }}
    - --log_output_level={{ annotation .ObjectMeta `sidecar.istio.io/agentLogLevel` .Values.global.logging.level }}
  {{- if .Values.global.sts.servicePort }}
    - --stsPort={{ .Values.global.sts.servicePort }}
  {{- end }}
  {{- if .Values.global.logAsJson }}
    - --log_as_json
  {{- end }}
  {{- if .Values.global.proxy.lifecycle }}
    lifecycle:
      {{ toYaml .Values.global.proxy.lifecycle | indent 6 }}
  {{- end }}
    securityContext:
      runAsUser: {{ .ProxyUID | default "1337" }}
      runAsGroup: {{ .ProxyGID | default "1337" }}
    env:
    - name: PILOT_CERT_PROVIDER
      value: {{ .Values.global.pilotCertProvider }}
    - name: CA_ADDR
    {{- if .Values.global.caAddress }}
      value: {{ .Values.global.caAddress }}
    {{- else }}
      value: istiod{{- if not (eq .Values.revision "") }}-{{ .Values.revision }}{{- end }}.{{ .Values.global.istioNamespace }}.svc:15012
    {{- end }}
    - name: POD_NAME
      valueFrom:
        fieldRef:
          fieldPath: metadata.name
    - name: POD_NAMESPACE
      valueFrom:
        fieldRef:
          fieldPath: metadata.namespace
    - name: INSTANCE_IP
      valueFrom:
        fieldRef:
          fieldPath: status.podIP
    - name: SERVICE_ACCOUNT
      valueFrom:
        fieldRef:
          fieldPath: spec.serviceAccountName
    - name: HOST_IP
      valueFrom:
        fieldRef:
          fieldPath: status.hostIP
    - name: ISTIO_CPU_LIMIT
      valueFrom:
        resourceFieldRef:
          resource: limits.cpu
    - name: PROXY_CONFIG
      value: |
            {{ protoToJSON .ProxyConfig }}
    - name: ISTIO_META_POD_PORTS
      value: |-
        [
        {{- $first := true }}
        {{- range $index1, $c := .Spec.Containers }}
          {{- range $index2, $p := $c.Ports }}
            {{- if (structToJSON $p) }}
            {{if not $first}},{{end}}{{ structToJSON $p }}
            {{- $first = false }}
            {{- end }}
          {{- end}}
        {{- end}}
        ]
    - name: GOMEMLIMIT
      valueFrom:
        resourceFieldRef:
          resource: limits.memory
    - name: GOMAXPROCS
      valueFrom:
        resourceFieldRef:
          resource: limits.cpu
    {{- if .CompliancePolicy }}
    - name: COMPLIANCE_POLICY
      value: "{{ .CompliancePolicy }}"
    {{- end }}
    - name: ISTIO_META_APP_CONTAINERS
      value: "{{ $containers | join "," }}"
    - name: ISTIO_META_CLUSTER_ID
      value: "{{ valueOrDefault .Values.global.multiCluster.clusterName `Kubernetes` }}"
    - name: ISTIO_META_NODE_NAME
      valueFrom:
        fieldRef:
          fieldPath: spec.nodeName
    - name: ISTIO_META_INTERCEPTION_MODE
      value: "{{ .ProxyConfig.InterceptionMode.String }}"
    {{- if .Values.global.network }}
    - name: ISTIO_META_NETWORK
      value: "{{ .Values.global.network }}"
    {{- end }}
    {{- if .DeploymentMeta.Name }}
    - name: ISTIO_META_WORKLOAD_NAME
      value: "{{ .DeploymentMeta.Name }}"
    {{ end }}
    {{- if and .TypeMeta.APIVersion .DeploymentMeta.Name }}
    - name: ISTIO_META_OWNER
      value: kubernetes://apis/{{ .TypeMeta.APIVersion }}/namespaces/{{ valueOrDefault .DeploymentMeta.Namespace `default` }}/{{ toLower .TypeMeta.Kind}}s/{{ .DeploymentMeta.Name }}
    {{- end}}
    {{- if .Values.global.meshID }}
    - name: ISTIO_META_MESH_ID
      value: "{{ .Values.global.meshID }}"
    {{- else if (valueOrDefault .MeshConfig.TrustDomain .Values.global.trustDomain) }}
    - name: ISTIO_META_MESH_ID
      value: "{{ (valueOrDefault .MeshConfig.TrustDomain .Values.global.trustDomain) }}"
    {{- end }}
    {{- with (valueOrDefault .MeshConfig.TrustDomain .Values.global.trustDomain)  }}
    - name: TRUST_DOMAIN
      value: "{{ . }}"
    {{- end }}
    {{- range $key, $value := .ProxyConfig.ProxyMetadata }}
    - name: {{ $key }}
      value: "{{ $value }}"
    {{- end }}
    {{with .Values.global.imagePullPolicy }}imagePullPolicy: "{{.}}"{{end}}
    readinessProbe:
      httpGet:
        path: /healthz/ready
        port: 15021
      initialDelaySeconds: {{.Values.global.proxy.readinessInitialDelaySeconds }}
      periodSeconds: {{ .Values.global.proxy.readinessPeriodSeconds }}
      timeoutSeconds: 3
      failureThreshold: {{ .Values.global.proxy.readinessFailureThreshold }}
    volumeMounts:
    - name: workload-socket
      mountPath: /var/run/secrets/workload-spiffe-uds
    - name: credential-socket
      mountPath: /var/run/secrets/credential-uds
    {{- if eq .Values.global.caName "GkeWorkloadCertificate" }}
    - name: gke-workload-certificate
      mountPath: /var/run/secrets/workload-spiffe-credentials
      readOnly: true
    {{- else }}
    - name: workload-certs
      mountPath: /var/run/secrets/workload-spiffe-credentials
    {{- end }}
    {{- if eq .Values.global.pilotCertProvider "istiod" }}
    - mountPath: /var/run/secrets/istio
      name: istiod-ca-cert
    {{- end }}
    - mountPath: /var/lib/istio/data
      name: istio-data
    # SDS channel between istioagent and Envoy
    - mountPath: /etc/istio/proxy
      name: istio-envoy
    - mountPath: /var/run/secrets/tokens
      name: istio-token
    {{- if .Values.global.mountMtlsCerts }}
    # Use the key and cert mounted to /etc/certs/ for the in-cluster mTLS communications.
    - mountPath: /etc/certs/
      name: istio-certs
      readOnly: true
    {{- end }}
    - name: istio-podinfo
      mountPath: /etc/istio/pod
  volumes:
  - emptyDir: {}
    name: workload-socket
  - emptyDir: {}
    name: credential-socket
  {{- if eq .Values.global.caName "GkeWorkloadCertificate" }}
  - name: gke-workload-certificate
    csi:
      driver: workloadcertificates.security.cloud.google.com
  {{- else}}
  - emptyDir: {}
    name: workload-certs
  {{- end }}
  # SDS channel between istioagent and Envoy
  - emptyDir:
      medium: Memory
    name: istio-envoy
  - name: istio-data
    emptyDir: {}
  - name: istio-podinfo
    downwardAPI:
      items:
        - path: "labels"
          fieldRef:
            fieldPath: metadata.labels
        - path: "annotations"
          fieldRef:
            fieldPath: metadata.annotations
  - name: istio-token
    projected:
      sources:
      - serviceAccountToken:
          path: istio-token
          expirationSeconds: 43200
          audience: {{ .Values.global.sds.token.aud }}
  {{- if eq .Values.global.pilotCertProvider "istiod" }}
  - name: istiod-ca-cert
  {{- if eq (.Values.pilot.env).ENABLE_CLUSTER_TRUST_BUNDLE_API true }}
    projected:
      sources:
      - clusterTrustBundle:
        name: istio.io:istiod-ca:root-cert
        path: root-cert.pem
  {{- else }}
    configMap:
      name: istio-ca-root-cert
  {{- end }}
  {{- end }}
  {{- if .Values.global.mountMtlsCerts }}
  # Use the key and cert mounted to /etc/certs/ for the in-cluster mTLS communications.
  - name: istio-certs
    secret:
      optional: true
      {{ if eq .Spec.ServiceAccountName "" }}
      secretName: istio.default
      {{ else -}}
      secretName: {{  printf "istio.%s" .Spec.ServiceAccountName }}
      {{  end -}}
  {{- end }}
  {{- if .Values.global.imagePullSecrets }}
  imagePullSecrets:
    {{- range .Values.global.imagePullSecrets }}
    - name: {{ . }}
    {{- end }}
  {{- end }}

Remove sysctls because net.ipv4.ip_unprivileged_port_start is not available on old Linux kernels.
Add CAP_NET_BIND_SERVICE to the list of capabilities in order to allow gateways to listen on ports below 1024.

Patch the default gateway injection template for Istio resource:

TEMPLATE_CONTENT=$(cat gateway-injection-template.txt)
PATCH_DATA=$(jq -n \
  --arg template "${TEMPLATE_CONTENT}" \
  '{
    "spec": {
      "values": {
        "sidecarInjectorWebhook": {
          "templates": {
            "gateway": $template
          }
        }
      }
    }
  }')
# Finally apply the patch to the Istio resource named `default`:
kubectl patch istio default --type=merge -p "${PATCH_DATA}"

Wait for the control plane to return the Ready status condition by running the following command:
```
kubectl wait --for condition=Ready istio/default --timeout=3m
```

#About gateway injection

#TOC

#Linux Kernel Compatibility Notice

#Prerequisites

#Procedure

About gateway injection

TOC

Linux Kernel Compatibility Notice

Prerequisites

Procedure