Overview

In this guide, you deploy a sidecar mesh to each workload cluster, create an east-west gateway in each cluster, and link the istiod control planes across cluster networks by using peering gateways. In the next guide, you can deploy the Bookinfo sample app to the sidecar mesh in each cluster, and make select services available across the multicluster mesh. Incoming requests can then be routed from an ingress gateway, such as Gloo Gateway, to services in your mesh across all clusters.

The following diagram demonstrates a service mesh setup across multiple clusters.

Figure: Multicluster service mesh set up with the Solo distribution of Istio and Gloo Gateway.
Figure: Multicluster service mesh set up with the Solo distribution of Istio and Gloo Gateway.

Considerations

Before you install a multicluster sidecar mesh, review the following considerations and requirements.

License requirements

Version requirements

Review the following known Istio version requirements and restrictions.

  • Patch versions 1.26.0 and 1.26.1 of the Solo distribution of Istio lack support for FIPS-tagged images and ztunnel outlier detection. When upgrading or installing 1.26, be sure to use patch version 1.26.1-patch0 and later only.
  • In the Solo distribution of Istio 1.25 and later, you can access enterprise-level features by passing your Solo license in the license.value or license.secretRef field of the Solo distribution of the istiod Helm chart. The Solo istiod Helm chart is strongly recommended due to the included safeguards, default settings, and upgrade handling to ensure a reliable and secure Istio deployment. Though it is not recommended, you can pass your license key in the open source istiod Helm chart by using the --set pilot.env.SOLO_LICENSE_KEY field.
  • Multicluster setups require the Solo distribution of Istio version 1.24.3 or later (1.24.3-solo), including the Solo distribution of istioctl.
  • Due to a lack of support for the Istio CNI and iptables for the Istio proxy, you cannot run Istio (and therefore Solo Enterprise for Istio) on AWS Fargate. For more information, see the Amazon EKS issue.

Components

In the following steps, you install the Istio ambient components in each workload cluster to successfully create east-west gateways and establish multicluster peering, even if you plan to use a sidecar mesh. However, sidecar mesh setups continue to use sidecar injection for your workloads. Your workloads are not added to an ambient mesh. For more information about running both ambient and sidecar components in one mesh setup, see Ambient-sidecar interoperability.

Platform requirements

The steps in the following sections have options for deploying a multicluster mesh to either Kubernetes or OpenShift clusters.

If you use OpenShift clusters, complete the following steps before you begin:

The commands for OpenShift in the following steps contain these required settings:

  • Your Helm settings must include global.platform=openshift for Istio 1.24 and later. If you instead install Istio 1.23 or earlier, you must use profile=openshift instead of the global.platform setting.
  • Install the istio-cni and ztunnel Helm releases in the kube-system namespace, instead of the istio-system namespace.

Revision and canary upgrade limitations

The upgrade guides in this documentation show you how to perform in-place upgrades for your Istio components, which is the recommended upgrade strategy.

Set up tools

  1. Set your Enterprise level license for Solo Enterprise for Istio as an environment variable. If you do not have one, contact an account representative. If you prefer to specify license keys in a secret instead, see Licensing. Note that you might have previously saved this key in another variable, such as ${SOLO_LICENSE_KEY} or ${GLOO_MESH_LICENSE_KEY}.

      export SOLO_ISTIO_LICENSE_KEY=<enterprise_license_key>

  2. Save the following environment details for the Solo distribution of Istio.

    1. Choose the version of Istio that you want to install or upgrade to by reviewing the supported versions. In Solo Enterprise for Istio version 2.7 and later, multicluster setups require version 1.24.3 or later.

    2. Decide on the specific tag of Solo distribution of Istio image, such as -solo, -solo-fips, -solo-distroless, or -solo-fips-distroless, that you want for your environment.

    3. Save the Solo distribution of Istio patch version and tag.

        # Change the tags as needed
export ISTIO_IMAGE=1.27.4-solo

    4. Save the repo key for the minor version of the Solo distribution of Istio. This is the 12-character hash at the end of the repo URL us-docker.pkg.dev/gloo-mesh/istio-<repo-key>, which you can find in the Istio images built by Solo.io support article.

        # 12-character hash at the end of the repo URL
export REPO_KEY=<repo_key>
export REPO=us-docker.pkg.dev/gloo-mesh/istio-${REPO_KEY}
export HELM_REPO=us-docker.pkg.dev/gloo-mesh/istio-helm-${REPO_KEY}

  3. Get the Solo distribution of Istio binary and install istioctl, which you use for multicluster linking and gateway commands. This script automatically detects your OS and architecture, downloads the appropriate Solo distribution of Istio binary, and verifies the installation.

      bash <(curl -sSfL https://raw.githubusercontent.com/solo-io/gloo-mesh-use-cases/main/gloo-mesh/install-istioctl.sh)
export PATH=${HOME}/.istioctl/bin:${PATH}

  4. Check the platform-specific prerequisites for ambient to determine whether you must make any changes to your environment before you install an ambient mesh.

  5. Deploy Istio to each cluster and link clusters. These steps vary based on whether you want to manually link meshes across clusters or use Solo Enterprise for Istio to automatically link clusters. Note that automatic linking is a beta feature, and requires Istio to be installed in the same cluster that the Gloo management plane is deployed to.

Option 1: Manually link meshes

In each cluster, use Helm to create the service mesh components. Then, create an east-west gateway so that traffic requests can be routed cross-cluster, and link clusters to enable cross-cluster service discovery.

Create a shared root of trust

Each cluster in the multicluster setup must have a shared root of trust. This can be achieved by providing a root certificate signed by a PKI provider, or a custom root certificate created for this purpose. The root certificate signs a unique intermediate CA certificate for each cluster.

By default, the Istio CA generates a self-signed root certificate and key, and uses them to sign the workload certificates. For more information, see the Plug in CA Certificates guide in the community Istio documentation.

For demo installations, you can run the following function to quickly generate and plug in the certificates and key for the Istio CA:

  curl -L https://istio.io/downloadIstio | ISTIO_VERSION=${ISTIO_VERSION} sh -
cd istio-${ISTIO_VERSION}

mkdir -p certs
pushd certs
make -f ../tools/certs/Makefile.selfsigned.mk root-ca

function create_cacerts_secret() {
  context=${1:?context}
  cluster=${2:?cluster}
  make -f ../tools/certs/Makefile.selfsigned.mk ${cluster}-cacerts
  kubectl --context=${context} create ns istio-system || true
  kubectl --context=${context} create secret generic cacerts -n istio-system \
    --from-file=${cluster}/ca-cert.pem \
    --from-file=${cluster}/ca-key.pem \
    --from-file=${cluster}/root-cert.pem \
    --from-file=${cluster}/cert-chain.pem
}

create_cacerts_secret ${REMOTE_CONTEXT1} ${REMOTE_CLUSTER1}
create_cacerts_secret ${REMOTE_CONTEXT2} ${REMOTE_CLUSTER2}

cd ../..

To enhance the security of your setup even further and have full control over the Istio CA lifecycle, you can generate and store the root and intermediate CA certificates and keys with your own PKI provider. You can then use tools such as cert-manager to send certificate signing requests on behalf of istiod to your PKI provider. Cert-manager stores the signed intermediate certificates and keys in the cacerts Kubernetes secret so that istiod can use these credentials to issue leaf certificates for the workloads in the service mesh. You can set up cert-manager to also check the certificates and renew them before they expire.

AWS Private CA issuer and cert-manager: For an architectural overview of this certificate setup, see Bring your own Istio CAs with AWS. For steps on how to deploy this certificate setup, check out this Solo.io blog post. Be sure to repeat the steps so that a cacerts secret exists in each cluster.

Deploy mesh components

  1. Save the name and kubeconfig context of a cluster where you want to install Istio in the following environment variables. Each time you repeat the steps in this guide, you change these variables to the next workload cluster’s name and context.

      export CLUSTER_NAME=<cluster-name>
export CLUSTER_CONTEXT=<cluster-context>

  2. Apply the CRDs for the Kubernetes Gateway API to your cluster, which are required to create components such as waypoint proxies for L7 traffic policies, gateways with the Gateway resource, and more.

      kubectl apply -f https://github.com/kubernetes-sigs/gateway-api/releases/download/v1.3.0/standard-install.yaml --context ${CLUSTER_CONTEXT}

  3. Install the base chart, which contains the CRDs and cluster roles required to set up Istio.

      helm upgrade --install istio-base oci://${HELM_REPO}/base \
--namespace istio-system \
--kube-context ${CLUSTER_CONTEXT} \
--version ${ISTIO_IMAGE} \
--create-namespace \
-f - <<EOF
profile: ambient
revision: main
global:
  istioNamespace: istio-system
EOF
  
      helm upgrade --install istio-base oci://${HELM_REPO}/base \
--namespace istio-system \
--create-namespace \
--kube-context ${CLUSTER_CONTEXT} \
--version ${ISTIO_IMAGE} \
-f - <<EOF
profile: ambient
revision: main
global:
  istioNamespace: istio-system
  platform: openshift
EOF

    You can optionally verify that the CRDs are successfully installed by running the following command.

      kubectl get crds -l app.kubernetes.io/instance=istio-base --kube-context ${CLUSTER_CONTEXT}

    Example output:

      NAME                                       CREATED AT
authorizationpolicies.security.istio.io    2025-12-16T22:56:00Z
destinationrules.networking.istio.io       2025-12-16T22:56:00Z
envoyfilters.networking.istio.io           2025-12-16T22:56:00Z
gateways.networking.istio.io               2025-12-16T22:56:00Z
peerauthentications.security.istio.io      2025-12-16T22:56:00Z
proxyconfigs.networking.istio.io           2025-12-16T22:56:00Z
requestauthentications.security.istio.io   2025-12-16T22:56:00Z
segments.admin.solo.io                     2025-12-16T22:56:00Z
serviceentries.networking.istio.io         2025-12-16T22:56:00Z
sidecars.networking.istio.io               2025-12-16T22:56:00Z
telemetries.telemetry.istio.io             2025-12-16T22:56:00Z
virtualservices.networking.istio.io        2025-12-16T22:56:00Z
wasmplugins.extensions.istio.io            2025-12-16T22:56:00Z
workloadentries.networking.istio.io        2025-12-16T22:56:00Z
workloadgroups.networking.istio.io         2025-12-16T22:56:00Z

  4. Create the istiod control plane in your cluster.

      helm upgrade --install istiod oci://${HELM_REPO}/istiod \
--namespace istio-system \
--kube-context ${CLUSTER_CONTEXT} \
--version ${ISTIO_IMAGE} \
-f - <<EOF
global:
  hub: ${REPO}
  variant: distroless
  proxy:
    clusterDomain: cluster.local
  tag: ${ISTIO_IMAGE}
  multiCluster:
    clusterName: ${CLUSTER_NAME}
  network: ${CLUSTER_NAME}
profile: ambient
revision: main
pilot:
  cni:
    enabled: true
meshConfig:
  accessLogFile: /dev/stdout
  defaultConfig:
    proxyMetadata:
      ISTIO_META_DNS_AUTO_ALLOCATE: "true"
      ISTIO_META_DNS_CAPTURE: "true"
  trustDomain: ${CLUSTER_NAME}
pilot:
  affinity:
    podAntiAffinity:
      preferredDuringSchedulingIgnoredDuringExecution:
        - podAffinityTerm:
            labelSelector:
              matchExpressions:
              - key: istio.io/rev
                operator: In
                values:
                - main
            topologyKey: topology.kubernetes.io/zone
          weight: 100
  enabled: true
  env:
    PILOT_ENABLE_IP_AUTOALLOCATE: "true"
    PILOT_ENABLE_K8S_SELECT_WORKLOAD_ENTRIES: "false"
    PILOT_SKIP_VALIDATE_TRUST_DOMAIN: "true"
    AUTO_RELOAD_PLUGIN_CERTS: "true"
    PILOT_ENABLE_WORKLOAD_ENTRY_AUTOREGISTRATION: "true"
    PILOT_ENABLE_WORKLOAD_ENTRY_HEALTHCHECKS: "true"
platforms:
  peering:
    enabled: true
revisionTags:
- default
license:
  value: ${SOLO_ISTIO_LICENSE_KEY}
  # Uncomment if you prefer to specify your license secret
  # instead of an inline value.
  # secretRef:
  #   name: 
  #   namespace: 
EOF
  
      helm upgrade --install istiod oci://${HELM_REPO}/istiod \
--namespace istio-system \
--kube-context ${CLUSTER_CONTEXT} \
--version ${ISTIO_IMAGE} \
-f - <<EOF
global:
  hub: ${REPO}
  variant: distroless
  platform: openshift
  proxy:
    clusterDomain: cluster.local
  tag: ${ISTIO_IMAGE}
  multiCluster:
    clusterName: ${CLUSTER_NAME}
  network: ${CLUSTER_NAME}
profile: ambient
revision: main
pilot:
  cni:
    namespace: kube-system
    enabled: true
meshConfig:
  accessLogFile: /dev/stdout
  defaultConfig:
    proxyMetadata:
      ISTIO_META_DNS_AUTO_ALLOCATE: "true"
      ISTIO_META_DNS_CAPTURE: "true"
  trustDomain: ${CLUSTER_NAME}
pilot:
  affinity:
    podAntiAffinity:
      preferredDuringSchedulingIgnoredDuringExecution:
        - podAffinityTerm:
            labelSelector:
              matchExpressions:
              - key: istio.io/rev
                operator: In
                values:
                - main
            topologyKey: topology.kubernetes.io/zone
          weight: 100
  enabled: true
  env:
    PILOT_ENABLE_IP_AUTOALLOCATE: "true"
    PILOT_ENABLE_K8S_SELECT_WORKLOAD_ENTRIES: "false"
    PILOT_SKIP_VALIDATE_TRUST_DOMAIN: "true"
    AUTO_RELOAD_PLUGIN_CERTS: "true"
    PILOT_ENABLE_WORKLOAD_ENTRY_AUTOREGISTRATION: "true"
    PILOT_ENABLE_WORKLOAD_ENTRY_HEALTHCHECKS: "true"
platforms:
  peering:
    enabled: true
revisionTags:
- default
license:
  value: ${SOLO_ISTIO_LICENSE_KEY}
  # Uncomment if you prefer to specify your license secret
  # instead of an inline value.
  # secretRef:
  #   name: 
  #   namespace: 
EOF

  5. Install the Istio CNI node agent daemonset. Note that although the CNI is included in this section, it is technically not part of the control plane or data plane.

      helm upgrade --install istio-cni oci://${HELM_REPO}/cni \
--namespace istio-system \
--kube-context=${CLUSTER_CONTEXT} \
--version ${ISTIO_IMAGE} \
-f - <<EOF
global:
  hub: ${REPO}
  proxy: ${ISTIO_IMAGE}
  variant: distroless
profile: ambient
revision: main
cni:
  ambient:
    dnsCapture: true
  excludeNamespaces:
  - istio-system
  - kube-system
EOF
  
      helm upgrade --install istio-cni oci://${HELM_REPO}/cni \
--namespace kube-system \
--kube-context=${CLUSTER_CONTEXT} \
--version ${ISTIO_IMAGE} \
--create-namespace \
-f - <<EOF
global:
  hub: ${REPO}
  proxy: ${ISTIO_IMAGE}
  variant: distroless
  platform: openshift
profile: ambient
revision: main
cni:
  ambient:
    dnsCapture: true
  excludeNamespaces:
  - istio-system
  - kube-system
EOF

  6. Verify that the components of the Istio control plane are successfully installed. Because the Istio CNI is deployed as a daemon set, the number of CNI pods equals the number of nodes in your cluster. Note that it might take a few seconds for the pods to become available.

      kubectl get pods -A --context ${CLUSTER_CONTEXT} | grep istio

    Example output:

      istio-system   istio-cni-node-g84js                   1/1     Running   0          8s
istio-system   istio-cni-node-gwssc                   1/1     Running   0          8s
istio-system   istiod-main-7c59ff7bd7-4mc25           1/1     Running   0          19s

  7. Optional: Check the istiod logs to verify that the certificate you generated earlier is picked up by istiod.

      kubectl logs deploy/istiod -n istio-system --context ${CLUSTER_CONTEXT} | grep x509

    Example output:

      2025-12-16T22:59:06.783901Z     info    x509 cert - Issuer: "CN=Intermediate CA,O=Istio,L=cluster-1", Subject: "", SN: def320623729b8370172413749143836, NotBefore: "2025-12-16T22:57:06Z", NotAfter: "2035-12-14T22:59:06Z"
2025-12-16T22:59:06.783937Z     info    x509 cert - Issuer: "CN=Root CA,O=Istio", Subject: "CN=Intermediate CA,O=Istio,L=cluster-1", SN: 452d45254328667ccf8434c64c79fe789612bb5a, NotBefore: "2025-12-16T22:54:30Z", NotAfter: "2035-12-14T22:54:30Z"
2025-12-16T22:59:06.783966Z     info    x509 cert - Issuer: "CN=Root CA,O=Istio", Subject: "CN=Root CA,O=Istio", SN: 38dad68e56ab8c506ae07454801f65b134bd9580, NotBefore: "2025-12-16T22:54:30Z", NotAfter: "2035-12-14T22:54:30Z"

  8. Install the ztunnel daemonset. Note that this component is required to successfully peer clusters together.

      helm upgrade --install ztunnel oci://${HELM_REPO}/ztunnel \
--namespace istio-system \
--kube-context=${CLUSTER_CONTEXT} \
--version ${ISTIO_IMAGE} \
-f - <<EOF
configValidation: true
enabled: true
env:
  L7_ENABLED: "true"
  ISTIO_META_DNS_CAPTURE: "true"
  SKIP_VALIDATE_TRUST_DOMAIN: "true"
hub: ${REPO}
istioNamespace: istio-system
multiCluster:
  clusterName: ${CLUSTER_NAME}
network: ${CLUSTER_NAME}
namespace: istio-system
profile: ambient
proxy:
  clusterDomain: cluster.local
tag: ${ISTIO_IMAGE}
variant: distroless
revision: main
EOF
  
      helm upgrade --install ztunnel oci://${HELM_REPO}/ztunnel \
--namespace kube-system \
--kube-context=${CLUSTER_CONTEXT} \
--version ${ISTIO_IMAGE} \
-f - <<EOF
configValidation: true
enabled: true
env:
  L7_ENABLED: "true"
  ISTIO_META_DNS_CAPTURE: "true"
  SKIP_VALIDATE_TRUST_DOMAIN: "true"
hub: ${REPO}
istioNamespace: istio-system
multiCluster:
  clusterName: ${CLUSTER_NAME}
network: ${CLUSTER_NAME}
namespace: kube-system
profile: ambient
global: 
  platform: openshift
proxy:
  clusterDomain: cluster.local
tag: ${ISTIO_IMAGE}
terminationGracePeriodSeconds: 29
variant: distroless
revision: main
EOF

  9. Verify that the ztunnel pods are successfully installed. Because the ztunnel is deployed as a daemon set, the number of pods equals the number of nodes in your cluster. Note that it might take a few seconds for the pods to become available.

      kubectl get pods -A --context ${CLUSTER_CONTEXT} | grep ztunnel

    Example output:

      ztunnel-tvtzn             1/1     Running   0          7s
ztunnel-vtpjm             1/1     Running   0          4s
ztunnel-hllxg             1/1     Running   0          4s

  10. Label the istio-system namespace with the cluster’s network name, which you previously set to your cluster’s name in the global.network field of the istiod installation. The Istio control plane uses this label internally to group pods that exist in the same L3 network.

      kubectl label namespace istio-system --context ${CLUSTER_CONTEXT} topology.istio.io/network=${CLUSTER_NAME}

  11. Create an east-west gateway in the istio-eastwest namespace. In each cluster, the east-west gateway is implemented as a ztunnel that facilitates traffic between services across clusters in your multicluster mesh. You can use the following istioctl command to quickly create the east-west gateway configuration. For customization options, see the gateway guide in the Istio docs.

      kubectl create namespace istio-eastwest --context ${CLUSTER_CONTEXT}
istioctl multicluster expose --namespace istio-eastwest --context ${CLUSTER_CONTEXT} --generate > ew-gateway.yaml
kubectl apply -f ew-gateway.yaml --context ${CLUSTER_CONTEXT}

    In this example generated Gateway resource, the gatewayClassName that is used, istio-eastwest, is included by default when you install Istio in ambient mode. For customization options, see the gateway guide in the Istio docs.

      apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  labels:
    istio.io/expose-istiod: "15012"
    topology.istio.io/network: "cluster1"
    topology.kubernetes.io/region: "us-east"
    topology.kubernetes.io/zone: "us-east-1"
  name: istio-eastwest
  namespace: istio-eastwest
spec:
  gatewayClassName: istio-eastwest
  listeners:
  - name: cross-network
    port: 15008
    protocol: HBONE
    tls:
      mode: Passthrough
  - name: xds-tls
    port: 15012
    protocol: TLS
    tls:
      mode: Passthrough

  12. Verify that the east-west gateway is successfully deployed.

      kubectl get pods -n istio-eastwest --context $CLUSTER_CONTEXT

  13. For each cluster that you want to include in the multicluster service mesh setup, repeat these steps to install the Gloo Operator, service mesh components, and east-west gateway in each cluster. Remember to change the cluster name and context variables each time you repeat the steps.

      export CLUSTER_NAME=<cluster-name>
export CLUSTER_CONTEXT=<cluster-context>

Link clusters to enable cross-cluster service discovery and allow traffic to be routed through east-west gateways across clusters.

  1. Optional: Before you link clusters, you can check the individual readiness of each cluster for linking by running the istioctl multicluster check --precheck command. For more information about this command, see the CLI reference. If any checks fail, run the command with --verbose, and see Validate your multicluster setup.

      istioctl multicluster check --precheck --contexts="<context1>,<context2>,<context3>"

    Before continuing to the next step, make sure that the following checks pass as expected:
    ✅ Relevant environment variables on istiod are supported.
    ✅ The license in use by istiod supports multicluster.
    ✅ All istiod, ztunnel, and east-west gateway pods are healthy.
    ✅ The east-west gateway is programmed.

  2. Link clusters to enable cross-cluster service discovery and allow traffic to be routed through east-west gateways across clusters. The steps vary based on whether you have access to the kubeconfig files for each cluster.

    1. Verify that the contexts for the clusters that you want to include in the multicluster mesh are listed in your kubeconfig file.

        kubectl config get-contexts
      • In the output, note the names of the cluster contexts, which you use in the next step to link the clusters.
      • If you have multiple kubeconfig files, you can generate a merged kubeconfig file by running the following command.
          KUBECONFIG=<kubeconfig_file1>.yaml:<file2>.yaml:<file3>.yaml kubectl config view --flatten

    2. Using the names of the cluster contexts, link the clusters so that they can communicate. Note that you can either link the clusters bi-directionally or asymmetrically. In a standard bi-directional setup, services in any of the linked clusters can send requests to and receive requests from the services in any of the other linked clusters. In an asymmetrical setup, you allow one cluster to send requests to another cluster, but the other cluster cannot send requests back to the first cluster.

      • Bi-directional: You can use the following istioctl command to quickly link the clusters bi-directionally. In each cluster, Gateway resources are created that use the istio-remote GatewayClass. This class allows the gateways to connect to other clusters by using the addresses of the east-west gateways.

          istioctl multicluster link --namespace istio-eastwest --contexts="<context1>,<context2>,<context3>"

        To take a look at the Gateway resources that this command creates, you can include the --generate flag in the command. For more information about this command, see the CLI reference.

        Example output for two clusters:

          Gateway istio-eastwest/istio-remote-peer-cluster1 applied to cluster "<cluster2_context>" pointing to cluster "<cluster1_context>" (network "cluster1")
Gateway istio-eastwest/istio-remote-peer-cluster2 applied to cluster "<cluster1_context>" pointing to cluster "<cluster2_context>" (network "cluster2")

      • Asymmetrical: You can use the following istioctl command to quickly link the clusters asymmetrically. The services in the cluster in the --from flag can send requests to services in the cluster in the --to flag, but sending requests in the reverse direction is not permitted.

          istioctl multicluster link --namespace istio-eastwest --from <context1> --to <context2>

        To take a look at the Gateway resources that this command creates, you can include the --generate flag in the command. For more information about this command, see the CLI reference.

        For example, this command allows services in cluster1’s mesh to send requests to services in cluster2’s mesh through cluster2’s east-west gateway. However, the reverse is not permitted: services in cluster2’s mesh cannot send requests through cluster1’s east-west gateway to services in cluster1.

          istioctl multicluster link --namespace istio-eastwest --from cluster1 --to cluster2

        Example output:

          Gateway istio-eastwest/istio-remote-peer-cluster2 applied to cluster "<cluster1_context>" pointing to cluster "<cluster2_context>" (network "cluster2")

    If you do not have access to all kubeconfig files for the clusters you want to link, or if you cannot combine the cluster contexts into one kubeconfig file, you can link the clusters by declaratively creating istio-remote peer gateways.

    Note that you can either link the clusters bi-directionally or asymmetrically. In a standard bi-directional setup, services in any of the linked clusters can send requests to and receive requests from the services in any of the other linked clusters. In an asymmetrical setup, you allow one cluster to send requests to another cluster, but the other cluster cannot send requests back to the first cluster.

    Bi-directional: You can use the following Gateway resources to create an istio-remote peer gateway in each cluster. The istio-remote GatewayClass allows the gateways to connect to other clusters by using the addresses of the east-west gateways.

    1. Get the addresses of the east-west gateway in each cluster. The following commands show examples for two clusters.

        export CLUSTER1_EW_ADDRESS=$(kubectl get svc -n istio-eastwest istio-eastwest --context $REMOTE_CONTEXT1 -o jsonpath="{.status.loadBalancer.ingress[0]['hostname','ip']}")
export CLUSTER2_EW_ADDRESS=$(kubectl get svc -n istio-eastwest istio-eastwest --context $REMOTE_CONTEXT2 -o jsonpath="{.status.loadBalancer.ingress[0]['hostname','ip']}")

echo "Cluster1 east-west gateway: $CLUSTER1_EW_ADDRESS"
echo "Cluster2 east-west gateway: $CLUSTER2_EW_ADDRESS"

    2. Using the east-west gateway addresses, create a Gateway resource in each cluster to represent the other cluster.

      • In the labels section, be sure to update the locality labels according to the region and zone of each cluster. For more information about locality support, see the release notes.
        kubectl apply --context $REMOTE_CONTEXT1 -f- <<EOF
apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  annotations:
    gateway.istio.io/service-account: istio-eastwest
    gateway.istio.io/trust-domain: $REMOTE_CLUSTER2
  labels:
    topology.istio.io/network: $REMOTE_CLUSTER2
    topology.kubernetes.io/region: "<cluster2_region>"
    topology.kubernetes.io/zone: "<cluster2_zone>"
  name: istio-remote-peer-$REMOTE_CLUSTER2
  namespace: istio-eastwest
spec:
  addresses:
  - type: IPAddress
    value: $CLUSTER2_EW_ADDRESS
  gatewayClassName: istio-remote
  listeners:
  - name: cross-network
    port: 15008
    protocol: HBONE
    tls:
      mode: Passthrough
  - name: xds-tls
    port: 15012
    protocol: TLS
    tls:
      mode: Passthrough
EOF

kubectl apply --context $REMOTE_CONTEXT2 -f- <<EOF
apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  annotations:
    gateway.istio.io/service-account: istio-eastwest
    gateway.istio.io/trust-domain: $REMOTE_CLUSTER1
  labels:
    topology.istio.io/network: $REMOTE_CLUSTER1
    topology.kubernetes.io/region: "<cluster1_region>"
    topology.kubernetes.io/zone: "<cluster1_zone>"
  name: istio-remote-peer-$REMOTE_CLUSTER1
  namespace: istio-eastwest
spec:
  addresses:
  - type: IPAddress
    value: $CLUSTER1_EW_ADDRESS
  gatewayClassName: istio-remote
  listeners:
  - name: cross-network
    port: 15008
    protocol: HBONE
    tls:
      mode: Passthrough
  - name: xds-tls
    port: 15012
    protocol: TLS
    tls:
      mode: Passthrough
EOF

    Asymmetrical: You can use the following Gateway resources to create an istio-remote peer gateway in only some clusters. The istio-remote GatewayClass allows the gateway in one cluster to connect to another cluster by using the address of the east-west gateway, but sending requests in the reverse direction is not permitted.

    1. Get the address of the east-west gateway in the cluster that you want to send traffic to. The following command shows an example for cluster2.

        export CLUSTER2_EW_ADDRESS=$(kubectl get svc -n istio-eastwest istio-eastwest --context $REMOTE_CONTEXT2 -o jsonpath="{.status.loadBalancer.ingress[0]['hostname','ip']}")

echo "Cluster2 east-west gateway: $CLUSTER2_EW_ADDRESS"

    2. Using the east-west gateway address, create a Gateway resource in the cluster that you want to send requests from. For example, this Gateway resource allows services in cluster1’s mesh to send requests to services in cluster2’s mesh through cluster2’s east-west gateway. However, the reverse is not permitted: services in cluster2’s mesh cannot send requests through cluster1’s east-west gateway to services in cluster1.

      • In the labels section, be sure to update the locality labels according to the region and zone of each cluster. For more information about locality support, see the release notes.
        kubectl apply --context $REMOTE_CONTEXT1 -f- <<EOF
apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  annotations:
    gateway.istio.io/service-account: istio-eastwest
    gateway.istio.io/trust-domain: $REMOTE_CLUSTER2
  labels:
    topology.istio.io/network: $REMOTE_CLUSTER2
    topology.kubernetes.io/region: "<cluster2_region>"
    topology.kubernetes.io/zone: "<cluster2_zone>"
  name: istio-remote-peer-$REMOTE_CLUSTER2
  namespace: istio-eastwest
spec:
  addresses:
  - type: IPAddress
    value: $CLUSTER2_EW_ADDRESS
  gatewayClassName: istio-remote
  listeners:
  - name: cross-network
    port: 15008
    protocol: HBONE
    tls:
      mode: Passthrough
  - name: xds-tls
    port: 15012
    protocol: TLS
    tls:
      mode: Passthrough
EOF

  3. Verify that peer linking was successful by running the istioctl multicluster check command. If any checks fail, run the command with --verbose, and see Validate your multicluster setup.

      istioctl multicluster check --contexts="<context1>,<context2>,<context3>"

    In this example output, the remote peer gateways are successfully connected, the intermediate certificates are compatible between the clusters, each cluster has a unique, properly configured network, and no stale workloads were found because no autogenerated workload entries existed in the clusters prior to peering. If you do have preexisting autogenerated workload entries, the check verifies whether all entries are up to date.

      === Cluster: cluster1 ===
✅ Incompatible Environment Variable Check: all relevant environment variables are valid
✅ License Check: license is valid for multicluster
✅ Pod Check (istiod): all pods healthy
✅ Pod Check (ztunnel): all pods healthy
✅ Pod Check (eastwest gateway): all pods healthy
✅ Gateway Check: all eastwest gateways programmed
✅ Peers Check: all clusters connected
====== 

=== Cluster: cluster2 ===
✅ Incompatible Environment Variable Check: all relevant environment variables are valid
✅ License Check: license is valid for multicluster
✅ Pod Check (istiod): all pods healthy
✅ Pod Check (ztunnel): all pods healthy
✅ Pod Check (eastwest gateway): all pods healthy
✅ Gateway Check: all eastwest gateways programmed
✅ Peers Check: all clusters connected
====== 

✅ Intermediate Certs Compatibility Check: all clusters have compatible intermediate certificates
✅ Network Configuration Check: all network configurations are valid
⚠  Stale Workloads Check: no autogenflat workload entries found

  4. Optional: Verify that the istiod control plane for each peered cluster is included in each cluster’s proxy status list.

      istioctl proxy-status --context $REMOTE_CONTEXT1
istioctl proxy-status --context $REMOTE_CONTEXT2

    Example output for cluster-1, in which you can verify that the istiod control plane for cluster-2 is listed:

      NAME                                               CLUSTER          ISTIOD                      VERSION              SUBSCRIBED TYPES
istio-eastwest-67fd5679dc-fhsxs.istio-eastwest     cluster-1        istiod-7b7c9cc4c6-bdm9c     1.27.4-solo-fips     2 (WADS,WDS)
istiod-6bc6765484-5bbhd.istio-system               cluster-2        istiod-7b7c9cc4c6-bdm9c     1.27.4-solo-fips     3 (FSDS,SGDS,WDS)
ztunnel-5f8rb.kube-system                          cluster-1        istiod-7b7c9cc4c6-bdm9c     1.27.4-solo-fips     2 (WADS,WDS)
ztunnel-f96kh.kube-system                          cluster-1        istiod-7b7c9cc4c6-bdm9c     1.27.4-solo-fips     2 (WADS,WDS)
ztunnel-vtj4f.kube-system                          cluster-1        istiod-7b7c9cc4c6-bdm9c     1.27.4-solo-fips     2 (WADS,WDS)

Next: Add apps to the sidecar mesh. For multicluster setups, this includes making specific services available across your linked cluster setup.

Option 2: Automatically link clusters (beta)

In each cluster, use Helm to create the service mesh components, and create an east-west gateway so that traffic requests can be routed cross-cluster. Then, use the Gloo management plane to automate multicluster linking, which enables cross-cluster service discovery.

Enable automatic peering of clusters

Upgrade Solo Enterprise for Istio in your multicluster setup to enable the ConfigDistribution feature flag and install the enterprise CRDs, which are required for Solo Enterprise for Istio to automate peering and distribute gateways between clusters.

  1. Upgrade your gloo-platform-crds Helm release in the management cluster to include the following settings.

      helm get values gloo-platform-crds -n gloo-mesh -o yaml --kube-context ${MGMT_CONTEXT} > mgmt-crds.yaml
helm upgrade gloo-platform-crds gloo-platform/gloo-platform-crds \
    --kube-context ${MGMT_CONTEXT} \
    --namespace gloo-mesh \
    -f mgmt-crds.yaml \
    --set featureGates.ConfigDistribution=true \
    --set installEnterpriseCrds=true

  2. Upgrade your gloo-platform Helm release in the management cluster to include the following settings.

      helm get values gloo-platform -n gloo-mesh -o yaml --kube-context ${MGMT_CONTEXT} > mgmt-plane.yaml
helm upgrade gloo-platform gloo-platform/gloo-platform \
    --kube-context ${MGMT_CONTEXT} \
    --namespace gloo-mesh \
    -f mgmt-plane.yaml \
    --set featureGates.ConfigDistribution=true

  3. Upgrade your gloo-platform-crds Helm release in each workload cluster to include the following settings. Repeat this step for each workload cluster.

      helm get values gloo-platform-crds -n gloo-mesh -o yaml --kube-context ${CLUSTER_CONTEXT} > crds.yaml
helm upgrade gloo-platform-crds gloo-platform/gloo-platform-crds \
    --kube-context ${CLUSTER_CONTEXT} \
    --namespace gloo-mesh \
    -f crds.yaml \
    --set installEnterpriseCrds=true

Create a shared root of trust

Create a shared root of trust for each cluster in the multicluster setup, including the management cluster. This can be achieved by providing a root certificate signed by a PKI provider, or a custom root certificate created for this purpose. The root certificate signs a unique intermediate CA certificate for each cluster.

By default, the Istio CA generates a self-signed root certificate and key, and uses them to sign the workload certificates. For more information, see the Plug in CA Certificates guide in the community Istio documentation.

For demo installations, you can run the following function to quickly generate and plug in the certificates and key for the Istio CA:

  curl -L https://istio.io/downloadIstio | ISTIO_VERSION=${ISTIO_VERSION} sh -
cd istio-${ISTIO_VERSION}

mkdir -p certs
pushd certs
make -f ../tools/certs/Makefile.selfsigned.mk root-ca

function create_cacerts_secret() {
  context=${1:?context}
  cluster=${2:?cluster}
  make -f ../tools/certs/Makefile.selfsigned.mk ${cluster}-cacerts
  kubectl --context=${context} create ns istio-system || true
  kubectl --context=${context} create secret generic cacerts -n istio-system \
    --from-file=${cluster}/ca-cert.pem \
    --from-file=${cluster}/ca-key.pem \
    --from-file=${cluster}/root-cert.pem \
    --from-file=${cluster}/cert-chain.pem
}

create_cacerts_secret ${MGMT_CONTEXT} ${MGMT_CLUSTER}
create_cacerts_secret ${REMOTE_CONTEXT1} ${REMOTE_CLUSTER1}
create_cacerts_secret ${REMOTE_CONTEXT2} ${REMOTE_CLUSTER2}

cd ../..

To enhance the security of your setup even further and have full control over the Istio CA lifecycle, you can generate and store the root and intermediate CA certificates and keys with your own PKI provider. You can then use tools such as cert-manager to send certificate signing requests on behalf of istiod to your PKI provider. Cert-manager stores the signed intermediate certificates and keys in the cacerts Kubernetes secret so that istiod can use these credentials to issue leaf certificates for the workloads in the service mesh. You can set up cert-manager to also check the certificates and renew them before they expire.

AWS Private CA issuer and cert-manager: For an architectural overview of this certificate setup, see Bring your own Istio CAs with AWS. For steps on how to deploy this certificate setup, check out this Solo.io blog post. Be sure to repeat the steps so that a cacerts secret exists in each cluster.

Deploy mesh components

  1. Save the name and kubeconfig context of a cluster where you want to install Istio in the following environment variables. Each time you repeat the steps in this guide, you change these variables to the next workload cluster’s name and context. Note that to use automated multicluster peering, you must complete these steps to install a service mesh in the management cluster as well as your workload clusters.

      export CLUSTER_NAME=<cluster-name>
export CLUSTER_CONTEXT=<cluster-context>

  2. Apply the CRDs for the Kubernetes Gateway API to your cluster, which are required to create components such as waypoint proxies for L7 traffic policies, gateways with the Gateway resource, and more.

      kubectl apply -f https://github.com/kubernetes-sigs/gateway-api/releases/download/v1.3.0/standard-install.yaml --context ${CLUSTER_CONTEXT}

  3. Install the base chart, which contains the CRDs and cluster roles required to set up Istio.

      helm upgrade --install istio-base oci://${HELM_REPO}/base \
--namespace istio-system \
--kube-context ${CLUSTER_CONTEXT} \
--version ${ISTIO_IMAGE} \
--create-namespace \
-f - <<EOF
profile: ambient
revision: main
global:
  istioNamespace: istio-system
EOF
  
      helm upgrade --install istio-base oci://${HELM_REPO}/base \
--namespace istio-system \
--create-namespace \
--kube-context ${CLUSTER_CONTEXT} \
--version ${ISTIO_IMAGE} \
-f - <<EOF
profile: ambient
revision: main
global:
  istioNamespace: istio-system
  platform: openshift
EOF

    You can optionally verify that the CRDs are successfully installed by running the following command.

      kubectl get crds -l app.kubernetes.io/instance=istio-base --kube-context ${CLUSTER_CONTEXT}

    Example output:

      NAME                                       CREATED AT
authorizationpolicies.security.istio.io    2025-12-16T22:56:00Z
destinationrules.networking.istio.io       2025-12-16T22:56:00Z
envoyfilters.networking.istio.io           2025-12-16T22:56:00Z
gateways.networking.istio.io               2025-12-16T22:56:00Z
peerauthentications.security.istio.io      2025-12-16T22:56:00Z
proxyconfigs.networking.istio.io           2025-12-16T22:56:00Z
requestauthentications.security.istio.io   2025-12-16T22:56:00Z
segments.admin.solo.io                     2025-12-16T22:56:00Z
serviceentries.networking.istio.io         2025-12-16T22:56:00Z
sidecars.networking.istio.io               2025-12-16T22:56:00Z
telemetries.telemetry.istio.io             2025-12-16T22:56:00Z
virtualservices.networking.istio.io        2025-12-16T22:56:00Z
wasmplugins.extensions.istio.io            2025-12-16T22:56:00Z
workloadentries.networking.istio.io        2025-12-16T22:56:00Z
workloadgroups.networking.istio.io         2025-12-16T22:56:00Z

  4. Create the istiod control plane in your cluster.

      helm upgrade --install istiod oci://${HELM_REPO}/istiod \
--namespace istio-system \
--kube-context ${CLUSTER_CONTEXT} \
--version ${ISTIO_IMAGE} \
-f - <<EOF
global:
  hub: ${REPO}
  variant: distroless
  proxy:
    clusterDomain: cluster.local
  tag: ${ISTIO_IMAGE}
  multiCluster:
    clusterName: ${CLUSTER_NAME}
  network: ${CLUSTER_NAME}
profile: ambient
revision: main
pilot:
  cni:
    enabled: true
meshConfig:
  accessLogFile: /dev/stdout
  defaultConfig:
    proxyMetadata:
      ISTIO_META_DNS_AUTO_ALLOCATE: "true"
      ISTIO_META_DNS_CAPTURE: "true"
  trustDomain: ${CLUSTER_NAME}
pilot:
  affinity:
    podAntiAffinity:
      preferredDuringSchedulingIgnoredDuringExecution:
        - podAffinityTerm:
            labelSelector:
              matchExpressions:
              - key: istio.io/rev
                operator: In
                values:
                - main
            topologyKey: topology.kubernetes.io/zone
          weight: 100
  enabled: true
  env:
    # Enables automatic creation of remote peer gateways
    PEERING_AUTOMATIC_LOCAL_GATEWAY: "true"
    PILOT_ENABLE_IP_AUTOALLOCATE: "true"
    PILOT_ENABLE_K8S_SELECT_WORKLOAD_ENTRIES: "false"
    PILOT_SKIP_VALIDATE_TRUST_DOMAIN: "true"
    AUTO_RELOAD_PLUGIN_CERTS: "true"
    PILOT_ENABLE_WORKLOAD_ENTRY_AUTOREGISTRATION: "true"
    PILOT_ENABLE_WORKLOAD_ENTRY_HEALTHCHECKS: "true"
platforms:
  peering:
    enabled: true
revisionTags:
- default
license:
  value: ${SOLO_ISTIO_LICENSE_KEY}
  # Uncomment if you prefer to specify your license secret
  # instead of an inline value.
  # secretRef:
  #   name: 
  #   namespace: 
EOF
  
      helm upgrade --install istiod oci://${HELM_REPO}/istiod \
--namespace istio-system \
--kube-context ${CLUSTER_CONTEXT} \
--version ${ISTIO_IMAGE} \
-f - <<EOF
global:
  hub: ${REPO}
  variant: distroless
  platform: openshift
  proxy:
    clusterDomain: cluster.local
  tag: ${ISTIO_IMAGE}
  multiCluster:
    clusterName: ${CLUSTER_NAME}
  network: ${CLUSTER_NAME}
profile: ambient
revision: main
pilot:
  cni:
    namespace: kube-system
    enabled: true
meshConfig:
  accessLogFile: /dev/stdout
  defaultConfig:
    proxyMetadata:
      ISTIO_META_DNS_AUTO_ALLOCATE: "true"
      ISTIO_META_DNS_CAPTURE: "true"
  trustDomain: ${CLUSTER_NAME}
pilot:
  affinity:
    podAntiAffinity:
      preferredDuringSchedulingIgnoredDuringExecution:
        - podAffinityTerm:
            labelSelector:
              matchExpressions:
              - key: istio.io/rev
                operator: In
                values:
                - main
            topologyKey: topology.kubernetes.io/zone
          weight: 100
  enabled: true
  env:
    PILOT_ENABLE_IP_AUTOALLOCATE: "true"
    PILOT_ENABLE_K8S_SELECT_WORKLOAD_ENTRIES: "false"
    PILOT_SKIP_VALIDATE_TRUST_DOMAIN: "true"
    AUTO_RELOAD_PLUGIN_CERTS: "true"
    PILOT_ENABLE_WORKLOAD_ENTRY_AUTOREGISTRATION: "true"
    PILOT_ENABLE_WORKLOAD_ENTRY_HEALTHCHECKS: "true"
platforms:
  peering:
    enabled: true
revisionTags:
- default
license:
  value: ${SOLO_ISTIO_LICENSE_KEY}
  # Uncomment if you prefer to specify your license secret
  # instead of an inline value.
  # secretRef:
  #   name: 
  #   namespace: 
EOF

  5. Install the Istio CNI node agent daemonset. Note that although the CNI is included in this section, it is technically not part of the control plane or data plane.

      helm upgrade --install istio-cni oci://${HELM_REPO}/cni \
--namespace istio-system \
--kube-context=${CLUSTER_CONTEXT} \
--version ${ISTIO_IMAGE} \
-f - <<EOF
global:
  hub: ${REPO}
  proxy: ${ISTIO_IMAGE}
  variant: distroless
profile: ambient
revision: main
cni:
  ambient:
    dnsCapture: true
  excludeNamespaces:
  - istio-system
  - kube-system
EOF
  
      helm upgrade --install istio-cni oci://${HELM_REPO}/cni \
--namespace kube-system \
--kube-context=${CLUSTER_CONTEXT} \
--version ${ISTIO_IMAGE} \
--create-namespace \
-f - <<EOF
global:
  hub: ${REPO}
  proxy: ${ISTIO_IMAGE}
  variant: distroless
  platform: openshift
profile: ambient
revision: main
cni:
  ambient:
    dnsCapture: true
  excludeNamespaces:
  - istio-system
  - kube-system
EOF

  6. Verify that the components of the Istio control plane are successfully installed. Because the Istio CNI is deployed as a daemon set, the number of CNI pods equals the number of nodes in your cluster. Note that it might take a few seconds for the pods to become available.

      kubectl get pods -A --context ${CLUSTER_CONTEXT} | grep istio

    Example output:

      istio-system   istio-cni-node-g84js                   1/1     Running   0          8s
istio-system   istio-cni-node-gwssc                   1/1     Running   0          8s
istio-system   istiod-main-7c59ff7bd7-4mc25           1/1     Running   0          19s

  7. Install the ztunnel daemonset. Note that this component is required to successfully peer clusters together.

      helm upgrade --install ztunnel oci://${HELM_REPO}/ztunnel \
--namespace istio-system \
--kube-context=${CLUSTER_CONTEXT} \
--version ${ISTIO_IMAGE} \
-f - <<EOF
configValidation: true
enabled: true
env:
  L7_ENABLED: "true"
  ISTIO_META_DNS_CAPTURE: "true"
  SKIP_VALIDATE_TRUST_DOMAIN: "true"
hub: ${REPO}
istioNamespace: istio-system
multiCluster:
  clusterName: ${CLUSTER_NAME}
network: ${CLUSTER_NAME}
namespace: istio-system
profile: ambient
proxy:
  clusterDomain: cluster.local
tag: ${ISTIO_IMAGE}
variant: distroless
revision: main
EOF
  
      helm upgrade --install ztunnel oci://${HELM_REPO}/ztunnel \
--namespace kube-system \
--kube-context=${CLUSTER_CONTEXT} \
--version ${ISTIO_IMAGE} \
-f - <<EOF
configValidation: true
enabled: true
env:
  L7_ENABLED: "true"
  ISTIO_META_DNS_CAPTURE: "true"
  SKIP_VALIDATE_TRUST_DOMAIN: "true"
hub: ${REPO}
istioNamespace: istio-system
multiCluster:
  clusterName: ${CLUSTER_NAME}
network: ${CLUSTER_NAME}
namespace: kube-system
profile: ambient
global: 
  platform: openshift
proxy:
  clusterDomain: cluster.local
tag: ${ISTIO_IMAGE}
terminationGracePeriodSeconds: 29
variant: distroless
revision: main
EOF

  8. Verify that the ztunnel pods are successfully installed. Because the ztunnel is deployed as a daemon set, the number of pods equals the number of nodes in your cluster. Note that it might take a few seconds for the pods to become available.

      kubectl get pods -A --context ${CLUSTER_CONTEXT} | grep ztunnel

    Example output:

      ztunnel-tvtzn             1/1     Running   0          7s
ztunnel-vtpjm             1/1     Running   0          4s
ztunnel-hllxg             1/1     Running   0          4s

  9. Label the istio-system namespace with the cluster’s network name, which you previously set to your cluster’s name in the global.network field of the istiod installation. The Istio control plane uses this label internally to group pods that exist in the same L3 network.

      kubectl label namespace istio-system --context ${CLUSTER_CONTEXT} topology.istio.io/network=${CLUSTER_NAME}

  10. Create an east-west gateway in the istio-eastwest namespace. In each cluster, the east-west gateway is implemented as a ztunnel that facilitates traffic between services across clusters in your multicluster mesh. You can use the following istioctl command to quickly create the east-west gateway configuration. For customization options, see the gateway guide in the Istio docs.

      kubectl create namespace istio-eastwest --context ${CLUSTER_CONTEXT}
istioctl multicluster expose --namespace istio-eastwest --context ${CLUSTER_CONTEXT} --generate > ew-gateway.yaml
kubectl apply -f ew-gateway.yaml --context ${CLUSTER_CONTEXT}

    In this example generated Gateway resource, the gatewayClassName that is used, istio-eastwest, is included by default when you install Istio in ambient mode. For customization options, see the gateway guide in the Istio docs.

      apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  labels:
    istio.io/expose-istiod: "15012"
    topology.istio.io/network: "cluster1"
    topology.kubernetes.io/region: "us-east"
    topology.kubernetes.io/zone: "us-east-1"
  name: istio-eastwest
  namespace: istio-eastwest
spec:
  gatewayClassName: istio-eastwest
  listeners:
  - name: cross-network
    port: 15008
    protocol: HBONE
    tls:
      mode: Passthrough
  - name: xds-tls
    port: 15012
    protocol: TLS
    tls:
      mode: Passthrough

  11. Verify that the east-west gateway is successfully deployed.

      kubectl get pods -n istio-eastwest --context $CLUSTER_CONTEXT

  12. For each cluster that you want to include in the multicluster service mesh setup, including the management cluster, repeat these steps to deploy service mesh components and an east-west gateway in each cluster. Remember to change the cluster name and context variables each time you repeat the steps.

      export CLUSTER_NAME=<cluster-name>
export CLUSTER_CONTEXT=<cluster-context>

Review remote peer gateways

After you complete the steps for each cluster, verify that Solo Enterprise for Istio successfully created and distributed the remote peering gateways. These gateways use the istio-remote GatewayClass, which allows the istiod control plane in each cluster to discover the east-west gateway addresses of other clusters. Solo Enterprise for Istio generates one istio-remote resource in the management cluster for each connected workload cluster, and then distributes the gateway to each cluster respectively.

  1. Verify that an istio-remote gateway for each connected cluster is copied to the management cluster.

      kubectl get gateways -n istio-eastwest --context $MGMT_CONTEXT

    In this example output, the istio-remote gateways that were auto-generated for workload clusters cluster1 and cluster2 are copied to the management cluster, alongside the management cluster’s own istio-remote gateway and east-west gateway.

      NAMESPACE        NAME                            CLASS           ADDRESS                                                                   PROGRAMMED   AGE
istio-eastwest   istio-eastwest                 istio-eastwest   a7f6f1a2611fc4eb3864f8d688622fd4-1234567890.us-east-1.elb.amazonaws.com   True         6s
istio-eastwest   istio-remote-peer-cluster1     istio-remote     a5082fe9522834b8192a6513eb8c6b01-0987654321.us-east-1.elb.amazonaws.com   True         4s
istio-eastwest   istio-remote-peer-cluster2     istio-remote     aaad62dc3ffb142a1bfc13df7fe9665b-5678901234.us-east-1.elb.amazonaws.com   True         4s
istio-eastwest   istio-remote-peer-mgmt         istio-remote     a7f6f1a2611fc4eb3864f8d688622fd4-1234567890.us-east-1.elb.amazonaws.com   True         4s

  2. In each cluster, verify that all istio-remote gateways are successfully distributed to all workload clusters. This ensures that services in each workload cluster can now access the east-west gateways in other clusters of the multicluster mesh setup.

      kubectl get gateways -n istio-eastwest --context $CLUSTER_CONTEXT

  3. In each cluster, verify that peer linking was successful by running the istioctl multicluster check command. For more information about this command, see the CLI reference. If any checks fail, run the command with --verbose, and see Validate your multicluster setup.

      istioctl multicluster check --context $CLUSTER_CONTEXT

    Example output for one cluster:

      ✅ Incompatible Environment Variable Check: all relevant environment variables are valid
✅ License Check: license is valid for multicluster
✅ Pod Check (istiod): all pods healthy
✅ Pod Check (ztunnel): all pods healthy
✅ Pod Check (eastwest gateway): all pods healthy
✅ Gateway Check: all eastwest gateways programmed
✅ Peers Check: all clusters connected
====== 

ℹ️ Intermediate Certs Compatibility Check: root certificate SHA256 sum: 909190c7c1eb242cfaf53aee23f484dba85105d5a259b141017e92fb9a0ce1b3
✅ Network Configuration Check: all network configurations are valid
⚠️ Stale Workloads Check: skipped (requires contexts for multiple clusters)

Next

Add apps to the sidecar mesh. For multicluster setups, this includes making specific services available across your linked cluster setup.

Optional: Validate your multicluster setup

Both before and after you link clusters into a multicluster mesh, you can use the istioctl multicluster check command, along with other observability checks, to verify multiple aspects of multicluster ambient mesh support and status.

For example, you can use the istioctl multicluster check --precheck command to check the individual readiness of each cluster before running istioctl multicluster link to link them in a multicluster mesh, and run it again after linking to confirm that the connections were successful. This command performs checks listed in the following sections, which you can review to understand what each check validates. Additionally, if any of the checks fail, run the command with the --verbose option, and review the following troubleshooting recommendations.

  istioctl multicluster check --verbose --contexts="<context1>,<context2>,<context3>"

For more information about this command, see the CLI reference.

Incompatible environment variables

Checks whether the ENABLE_PEERING_DISCOVERY=true and optionally K8S_SELECT_WORKLOAD_ENTRIES=true environment variables are set incorrectly or are not supported for multicluster ambient mesh.

Example verbose output:

  --- Incompatible Environment Variable Check ---

✅ Incompatible Environment Variable Check: K8S_SELECT_WORKLOAD_ENTRIES is valid ("")
✅ Incompatible Environment Variable Check: ENABLE_PEERING_DISCOVERY is valid ("true")
✅ Incompatible Environment Variable Check: all relevant environment variables are valid

If this check fails, check your environment variables in your istiod configuration, such as by running helm get values --kube-context ${CLUSTER_CONTEXT} istiod -n istio-system -o yaml, and update your configuration.

License validity

Checks whether the license in use by istiod is valid for multicluster ambient mesh. Multicluster capabilities require an Enterprise level license for Solo Enterprise for Istio.

Example verbose output:

  --- License Check ---

✅ License Check: license is valid for multicluster

If your license does not support multicluster ambient mesh, contact your Solo account representative.

Pod health

Checks the health of the pods in the cluster. All istiod, ztunnel, and east-west gateway pods across the checked clusters must be healthy and running for the multicluster mesh to function correctly.

Example verbose output:

  --- Pod Check (istiod) ---

NAME                        READY     STATUS      RESTARTS     AGE
istiod-6d9cdf88cf-l47tf     1/1       Running     0            10m18s

✅ Pod Check (istiod): all pods healthy


--- Pod Check (ztunnel) ---

NAME              READY     STATUS      RESTARTS     AGE
ztunnel-dvlwk     1/1       Running     0            10m6s

✅ Pod Check (ztunnel): all pods healthy


--- Pod Check (eastwest gateway) ---

NAME                                READY     STATUS      RESTARTS     AGE
istio-eastwest-857b77fc5d-qgnrl     1/1       Running     0            9m33s

✅ Pod Check (eastwest gateway): all pods healthy

To check any unhealthy pods, run the following commands. Consider checking the pod logs, and review Debug Istio.

  kubectl get po -n istio-system
kubectl get po -n istio-eastwest

East-west gateway status

Checks the status of the east-west gateways in the cluster. When an east-west gateway is created, the gateway controller creates a Kubernetes service to expose the gateway. Once this service is correctly attached to the gateway and has an address assigned, the east-west gateway has a Programmed status of true.

Example verbose output:

  --- Gateway Check ---

Gateway: istio-eastwest
Addresses:
- 172.18.7.110
Status: programmed ✅

✅ Gateway Check: all eastwest gateways programmed

If the Programmed status is not true, an issue might exist with the address allocation for the service. Check the east-west gateway with a command such as kubectl get svc -n istio-eastwest, and verify that your cloud provider can correctly allocate addresses to the service.

Remote peer gateway status

Checks the status of the remote peer gateways in the cluster, which represent the other peered clusters in the multicluster setup. These remote gateways configure the connection between the local cluster’s istiod control plane, and the peered clusters’ remote networks to enable XDS communication between peers. When the initial network connection between istiod and a remote peer is made, the gateway’s gloo.solo.io/PeerConnected status updates to true. Then, when the full XDS sync occurs between peers, the gateway’s gloo.solo.io/PeeringSucceeded status also updates to true.

Example verbose output:

  --- Peers Check ---

Cluster: cluster2
Addresses:
- 172.18.7.130
Conditions:
- Accepted: True
- Programmed: True
- gloo.solo.io/PeerConnected: True
- gloo.solo.io/PeeringSucceeded: True
- gloo.solo.io/PeerDataPlaneProgrammed: True
Status: connected ✅

✅ Peers Check: all clusters connected

If the connection is severed between the peers, the gloo.solo.io/PeerConnected status becomes false. A failed connection between peers can be due to either a misconfiguration in the peering setup, or a network issue blocking port 15008 on the remote cluster, which is the cross-network HBONE port that the east-west gateway listens on. Review the steps you took to link clusters together, such as the steps outlined in the Helm default network guide. Additionally, review any firewall rules or network policies that might block access through port 15008 on the remote cluster.

Intermediate certificate compatibility

Confirms the certificate compatibility between peered clusters. This check reads the root-cert.pem from the istio-ca-root-cert configmap in the istio-system namespace, and uses x509 certificate validation to confirm the root cert is compatible with all of the clusters’ ca-cert.pem intermediate certificate chains from the cacerts secret.

Example verbose output:

  --- Intermediate Certs Compatibility Check ---

ℹ  Intermediate Certs Compatibility Check: cluster cluster1 root certificate SHA256 sum: 6d18f32e134824c158d97f32618657c45d5a83839f838ada751757139481537e
ℹ  Intermediate Certs Compatibility Check: cluster cluster2 root certificate SHA256 sum: 6d18f32e134824c158d97f32618657c45d5a83839f838ada751757139481537e
✅ Intermediate Certs Compatibility Check: cluster cluster1 has compatible intermediate certificates with cluster cluster2 
✅ Intermediate Certs Compatibility Check: cluster cluster2 has compatible intermediate certificates with cluster cluster1 
✅ Intermediate Certs Compatibility Check: all clusters have compatible intermediate certificates

If this check fails because the root certs are not valid for each peered clusters’ intermediate certificate chain, you can check the istiod logs for TLS errors when attempting to communicate with a peered cluster, such as the following:

  2025-12-04T22:09:22.474517Z     warn    deltaadsc       disconnected, retrying in 24.735483751s: delta stream: rpc error: code = Unavailable desc = connection error: desc = "error reading server preface: remote error: tls: unknown certificate authority"       target=peering-cluster2

Ensure each cluster has a cacerts secret in the istio-system namespace. To regenerate invalid certificates for each cluster, follow the example steps in Create a shared root of trust.

Network configuration

Confirms the network configuration of the multicluster mesh. For multicluster peering setups that do not use a flat network topology, each cluster must occupy a unique network. The network name must be defined with the label topology.istio.io/network and set on both the istio-system namespace and the istio-eastwest gateway resource. The same network name must also be set as the NETWORK environment variable on the ztunnel daemonset. Each remote gateway that represents that cluster must have the topology.istio.io/network label equal to the network of the remote cluster.

Example verbose output:

  --- Network Configuration Check ---

✅ Cluster cluster1 has network: cluster1
✅ Eastwest gateway istio-eastwest/istio-eastwest has correct network label: cluster1
✅ Cluster cluster2 has network: cluster2
✅ Eastwest gateway istio-eastwest/istio-eastwest has correct network label: cluster2
✅ Remote gateway istio-eastwest/istio-remote-peer-cluster2 references network cluster2 (clusters: [cluster2])
✅ Remote gateway istio-eastwest/istio-remote-peer-cluster1 references network cluster1 (clusters: [cluster1])
✅ Network Configuration Check: all network configurations are valid

Mismatched network identities cause errors in cross-cluster communication, which leads to error logs in ztunnel pods that indicate a network timeout on the outbound communication. Notably, the destination address on these errors is a 240.X.X.X address, instead of the correct remote peer gateway address. You can run kubectl logs -l app=ztunnel -n istio-system --tail=10 --context ${CLUSTER_CONTEXT} | grep -iE "error|warn" to review logs such as the following:

  2025-11-18T16:14:53.490573Z     error   access  connection complete     src.addr=240.0.2.27:46802 src.workload="ratings-v1-5dc79b6bcd-zm8v6" src.namespace="bookinfo" src.identity="spiffe://cluster.local/ns/bookinfo/sa/bookinfo-ratings" dst.addr=240.0.9.43:15008 dst.hbone_addr=240.0.9.43:9080 dst.service="productpage.bookinfo.mesh.internal" dst.workload="autogenflat.portfolio1-soloiopoc-cluster1.bookinfo.productpage-v1-54bb874995-hblwp.ee508601917c" dst.namespace="bookinfo" dst.identity="spiffe://cluster.local/ns/bookinfo/sa/bookinfo-productpage" direction="outbound" bytes_sent=0 bytes_recv=0 duration="10001ms" error="connection timed out, maybe a NetworkPolicy is blocking HBONE port 15008: deadline has elapsed"

To troubleshoot these issues, be sure that you use unique network names to represent each cluster, and that you correctly labeled the cluster’s istio-system namespace with that network name, such as by running kubectl label namespace istio-system --context ${CLUSTER_CONTEXT} topology.istio.io/network=${CLUSTER_NAME}. You can also relabel the east-west gateway in the cluster, and the remote peer gateways in other clusters that represent this cluster.

Stale workload entries

In flat network setups, checks for any outdated workload entries that must be removed from the multicluster mesh. Stale workload entries might exist from pods that were deleted, but the autogenerated entries for those workloads were not correctly cleaned up. If you do not use a flat network topology, no autogenerated workload entries exist to be validated, and this check can be ignored.

Example verbose output for a non-flat network setup:

  --- Stale Workloads Check ---

⚠  Stale Workloads Check: no autogenflat workload entries found

If you use a flat network topology, and this check fails with stale workload entries, run kubectl get workloadentries -n istio-system | grep autogenflat to list the autogenerated workload entries in the remote cluster, and compare the list to the output of kubectl get pods in the source cluster for those workloads. You can safely manually delete the stale workload entries in the remote cluster for pods that no longer exist in the source cluster, such as by running kubectl get workloadentries -n istio-system <entry_name>.