---
title: Single-network Mesh Expansion
description: Integrate VMs and bare metal hosts into an Istio mesh deployed on Kubernetes.
weight: 20
keywords: [kubernetes,vms]
aliases:
    - /docs/setup/kubernetes/additional-setup/mesh-expansion/
---

This example provides instructions to integrate VMs and bare metal hosts into
an Istio mesh deployed on Kubernetes.

## Prerequisites

* You have already set up Istio on Kubernetes. If you haven't done so, you can find out how in the [Installation guide](/docs/setup/install/kubernetes/).

* Mesh expansion machines must have IP connectivity to the endpoints in the mesh. This
typically requires a VPC or a VPN, as well as a container network that
provides direct (without NAT or firewall deny) routing to the endpoints. The machine
is not required to have access to the cluster IP addresses assigned by Kubernetes.

* Mesh expansion VMs must have access to a DNS server that resolves names to cluster IP addresses. Options
include exposing the Kubernetes DNS server through an internal load balancer, using a Core DNS
server, or configuring the IPs in any other DNS server accessible from the VM.

* Install the [Helm client](https://docs.helm.sh/using_helm/). Helm is needed to enable mesh expansion.

The following instructions:

* Assume the expansion VM is running on GCE.
* Use Google platform-specific commands for some steps.

## Installation steps

Setup consists of preparing the mesh for expansion and installing and configuring each VM.

### Preparing the Kubernetes cluster for expansion

The first step when adding non-Kubernetes services to an Istio mesh is to configure the Istio installation itself, and
generate the configuration files that let mesh expansion VMs connect to the mesh. To prepare the
cluster for mesh expansion, run the following commands on a machine with cluster admin privileges:

1.  Ensure that mesh expansion is enabled for the cluster. If you didn't use
    the `--set global.meshExpansion.enabled=true` flag when installing Helm,
    you can use one of the following two options depending on how you originally installed
    Istio on the cluster:

    *   If you installed Istio with Helm and Tiller, run `helm upgrade` with the new option:

    {{< text bash >}}
    $ cd install/kubernetes/helm/istio
    $ helm upgrade --set global.meshExpansion.enabled=true istio .
    $ cd -
    {{< /text >}}

    *   If you installed Istio without Helm and Tiller, use `helm template` to update your configuration with the option and reapply with `kubectl`:

    {{< text bash >}}
    $ kubectl create namespace istio-system
    $ helm template  install/kubernetes/helm/istio-init --name istio-init --namespace istio-system  | kubectl apply -f -
    $ cd install/kubernetes/helm/istio
    $ helm template --set global.meshExpansion.enabled=true --namespace istio-system . > istio.yaml
    $ kubectl apply -f istio.yaml
    $ cd -
    {{< /text >}}

    {{< tip >}}
    When updating configuration with Helm, you can either set the option on the command line, as in our examples, or add
    it to a `.yaml` values file and pass it to
    the command with `--values`, which is the recommended approach when managing configurations with multiple options. You
    can see some sample values files in your Istio installation's `install/kubernetes/helm/istio` directory and find out
    more about customizing Helm charts in the [Helm documentation](https://docs.helm.sh/using_helm/#using-helm).
    {{< /tip >}}

1. Define the namespace the VM joins. This example uses the `SERVICE_NAMESPACE` environment variable to store the namespace. The value of this variable must match the namespace you use in the configuration files later on.

    {{< text bash >}}
    $ export SERVICE_NAMESPACE="default"
    {{< /text >}}

1. Determine and store the IP address of the Istio ingress gateway since the mesh expansion machines access [Citadel](/docs/concepts/security/) and [Pilot](/docs/concepts/traffic-management/#pilot) through this IP address.

    {{< text bash >}}
    $ export GWIP=$(kubectl get -n istio-system service istio-ingressgateway -o jsonpath='{.status.loadBalancer.ingress[0].ip}')
    $ echo $GWIP
    35.232.112.158
    {{< /text >}}

1. Generate a `cluster.env` configuration to deploy in the VMs. This file contains the Kubernetes cluster IP address ranges
    to intercept and redirect via Envoy. You specify the CIDR range when you install Kubernetes as `servicesIpv4Cidr`.
    Replace `$MY_ZONE` and `$MY_PROJECT` in the following example commands with the appropriate values to obtain the CIDR
    after installation:

    {{< text bash >}}
    $ ISTIO_SERVICE_CIDR=$(gcloud container clusters describe $K8S_CLUSTER --zone $MY_ZONE --project $MY_PROJECT --format "value(servicesIpv4Cidr)")
    $ echo -e "ISTIO_CP_AUTH=MUTUAL_TLS\nISTIO_SERVICE_CIDR=$ISTIO_SERVICE_CIDR\n" > cluster.env
    {{< /text >}}

1. Check the contents of the generated `cluster.env` file. It should be similar to the following example:

    {{< text bash >}}
    $ cat cluster.env
    ISTIO_CP_AUTH=MUTUAL_TLS
    ISTIO_SERVICE_CIDR=10.55.240.0/20
    {{< /text >}}

1. If the VM only calls services in the mesh, you can skip this step. Otherwise, add the ports the VM exposes
    to the `cluster.env` file with the following command. You can change the ports later if necessary.

    {{< text bash >}}
    $ echo "ISTIO_INBOUND_PORTS=3306,8080" >> cluster.env
    {{< /text >}}

1. Extract the initial keys the service account needs to use on the VMs.

    {{< text bash >}}
    $ kubectl -n $SERVICE_NAMESPACE get secret istio.default  \
        -o jsonpath='{.data.root-cert\.pem}' |base64 --decode > root-cert.pem
    $ kubectl -n $SERVICE_NAMESPACE get secret istio.default  \
        -o jsonpath='{.data.key\.pem}' |base64 --decode > key.pem
    $ kubectl -n $SERVICE_NAMESPACE get secret istio.default  \
          -o jsonpath='{.data.cert-chain\.pem}' |base64 --decode > cert-chain.pem
    {{< /text >}}

### Setting up the VM

Next, run the following commands on each machine that you want to add to the mesh:

1.  Copy the previously created `cluster.env` and `*.pem` files to the VM. For example:

    {{< text bash >}}
    $ export GCE_NAME="your-gce-instance"
    $ gcloud compute scp --project=${MY_PROJECT} --zone=${MY_ZONE} {key.pem,cert-chain.pem,cluster.env,root-cert.pem} ${GCE_NAME}:~
    {{< /text >}}

1.  Install the Debian package with the Envoy sidecar.

    {{< text bash >}}
    $ gcloud compute ssh --project=${MY_PROJECT} --zone=${MY_ZONE} "${GCE_NAME}"
    $ curl -L https://storage.googleapis.com/istio-release/releases/{{< istio_full_version >}}/deb/istio-sidecar.deb > istio-sidecar.deb
    $ sudo dpkg -i istio-sidecar.deb
    {{< /text >}}

1.  Add the IP address of the Istio gateway to `/etc/hosts`. Revisit the [preparing the cluster](#preparing-the-kubernetes-cluster-for-expansion) section to learn how to obtain the IP address.
The following example updates the `/etc/hosts` file with the Istio gateway address:

    {{< text bash >}}
    $ echo "35.232.112.158 istio-citadel istio-pilot istio-pilot.istio-system" | sudo tee -a /etc/hosts
    {{< /text >}}

1.  Install `root-cert.pem`, `key.pem` and `cert-chain.pem` under `/etc/certs/`.

    {{< text bash >}}
    $ sudo mkdir -p /etc/certs
    $ sudo cp {root-cert.pem,cert-chain.pem,key.pem} /etc/certs
    {{< /text >}}

1.  Install `cluster.env` under `/var/lib/istio/envoy/`.

    {{< text bash >}}
    $ sudo cp cluster.env /var/lib/istio/envoy
    {{< /text >}}

1.  Transfer ownership of the files in `/etc/certs/` and `/var/lib/istio/envoy/` to the Istio proxy.

    {{< text bash >}}
    $ sudo chown -R istio-proxy /etc/certs /var/lib/istio/envoy
    {{< /text >}}

1.  Verify the node agent works:

    {{< text bash >}}
    $ sudo node_agent
    ....
    CSR is approved successfully. Will renew cert in 1079h59m59.84568493s
    {{< /text >}}

1.  Start Istio using `systemctl`.

    {{< text bash >}}
    $ sudo systemctl start istio-auth-node-agent
    $ sudo systemctl start istio
    {{< /text >}}

## Send requests from VM workloads to Kubernetes services

After setup, the machine can access services running in the Kubernetes cluster
or on other mesh expansion machines.

The following example shows accessing a service running in the Kubernetes cluster from a mesh expansion VM using
`/etc/hosts/`, in this case using a service from the [Bookinfo example](/docs/examples/bookinfo/).

1.  First, on the cluster admin machine get the virtual IP address (`clusterIP`) for the service:

    {{< text bash >}}
    $ kubectl get svc productpage -o jsonpath='{.spec.clusterIP}'
    10.55.246.247
    {{< /text >}}

1.  Then on the mesh expansion machine, add the service name and address to its `etc/hosts` file. You can then connect to
    the cluster service from the VM, as in the example below:

    {{< text bash >}}
$ echo "10.55.246.247 productpage.default.svc.cluster.local" | sudo tee -a /etc/hosts
$ curl -v productpage.default.svc.cluster.local:9080
< HTTP/1.1 200 OK
< content-type: text/html; charset=utf-8
< content-length: 1836
< server: envoy
... html content ...
    {{< /text >}}

The `server: envoy` header indicates that the sidecar intercepted the traffic.

## Running services on a mesh expansion machine

1. Setup an HTTP server on the VM instance to serve HTTP traffic on port 8080:

    {{< text bash >}}
    $ gcloud compute ssh ${GCE_NAME}
    $ python -m SimpleHTTPServer 8080
    {{< /text >}}

1. Determine the VM instance's IP address. For example, find the IP address
    of the GCE instance with the following commands:

    {{< text bash >}}
    $ export GCE_IP=$(gcloud --format="value(networkInterfaces[0].networkIP)" compute instances describe ${GCE_NAME})
    $ echo ${GCE_IP}
    {{< /text >}}

1. Configure a service entry to enable service discovery for the VM. You can add VM services to the mesh using a
    [service entry](/docs/reference/config/networking/v1alpha3/service-entry/). Service entries let you manually add
    additional services to Pilot's abstract model of the mesh. Once VM services are part of the mesh's abstract model,
    other services can find and direct traffic to them. Each service entry configuration contains the IP addresses, ports,
    and appropriate labels of all VMs exposing a particular service, for example:

    {{< text bash yaml >}}
    $ kubectl -n ${SERVICE_NAMESPACE} apply -f - <<EOF
    apiVersion: networking.istio.io/v1alpha3
    kind: ServiceEntry
    metadata:
      name: vmhttp
    spec:
      hosts:
      - vmhttp.${SERVICE_NAMESPACE}.svc.cluster.local
      ports:
      - number: 8080
        name: http
        protocol: HTTP
      resolution: STATIC
      endpoints:
      - address: ${GCE_IP}
        ports:
          http: 8080
        labels:
          app: vmhttp
          version: "v1"
    EOF
    {{< /text >}}

1. The workloads in a Kubernetes cluster need a DNS mapping to resolve the domain names of VM services. To
    integrate the mapping with your own DNS system, use `istioctl register` and creates a Kubernetes `selector-less`
    service, for example:

    {{< text bash >}}
    $ istioctl  register -n ${SERVICE_NAMESPACE} vmhttp ${GCE_IP} 8080
    {{< /text >}}

    {{< tip >}}
    Make sure you have already added `istioctl` client to your `PATH` environment variable, as described in the Download page.
    {{< /tip >}}

1. Deploy a pod running the `sleep` service in the Kubernetes cluster, and wait until it is ready:

    {{< text bash >}}
    $ kubectl apply -f @samples/sleep/sleep.yaml@
    $ kubectl get pod
    NAME                             READY     STATUS    RESTARTS   AGE
    productpage-v1-8fcdcb496-xgkwg   2/2       Running   0          1d
    sleep-88ddbcfdd-rm42k            2/2       Running   0          1s
    ...
    {{< /text >}}

1. Send a request from the `sleep` service on the pod to the VM's HTTP service:

    {{< text bash >}}
    $ kubectl exec -it sleep-88ddbcfdd-rm42k -c sleep -- curl vmhttp.${SERVICE_NAMESPACE}.svc.cluster.local:8080
    {{< /text >}}

    You should see something similar to the output below.

    ```html
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html>
    <title>Directory listing for /</title>
    <body>
    <h2>Directory listing for /</h2>
    <hr>
    <ul>
    <li><a href=".bashrc">.bashrc</a></li>
    <li><a href=".ssh/">.ssh/</a></li>
    ...
    </body>
    ```

**Congratulations!** You successfully configured a service running in a pod within the cluster to
send traffic to a service running on a VM outside of the cluster and tested that
the configuration worked.

## Cleanup

Run the following commands to remove the expansion VM from the mesh's abstract
model.

{{< text bash >}}
$ istioctl deregister -n ${SERVICE_NAMESPACE} vmhttp ${GCE_IP}
2019-02-21T22:12:22.023775Z     info    Deregistered service successfull
$ kubectl delete ServiceEntry vmhttp -n ${SERVICE_NAMESPACE}
serviceentry.networking.istio.io "vmhttp" deleted
{{< /text >}}

## Troubleshooting

The following are some basic troubleshooting steps for common mesh expansion issues.

*    When making requests from a VM to the cluster, ensure you don't run the requests as `root` or
    `istio-proxy` user. By default, Istio excludes both users from interception.

*    Verify the machine can reach the IP of the all workloads running in the cluster. For example:

    {{< text bash >}}
    $ kubectl get endpoints productpage -o jsonpath='{.subsets[0].addresses[0].ip}'
    10.52.39.13
    {{< /text >}}

    {{< text bash >}}
    $ curl 10.52.39.13:9080
    html output
    {{< /text >}}

*    Check the status of the node agent and sidecar:

    {{< text bash >}}
    $ sudo systemctl status istio-auth-node-agent
    $ sudo systemctl status istio
    {{< /text >}}

*    Check that the processes are running. The following is an example of the processes you should see on the VM if you run
     `ps`, filtered for `istio`:

    {{< text bash >}}
    $ ps aux | grep istio
    root      6941  0.0  0.2  75392 16820 ?        Ssl  21:32   0:00 /usr/local/istio/bin/node_agent --logtostderr
    root      6955  0.0  0.0  49344  3048 ?        Ss   21:32   0:00 su -s /bin/bash -c INSTANCE_IP=10.150.0.5 POD_NAME=demo-vm-1 POD_NAMESPACE=default exec /usr/local/bin/pilot-agent proxy > /var/log/istio/istio.log istio-proxy
    istio-p+  7016  0.0  0.1 215172 12096 ?        Ssl  21:32   0:00 /usr/local/bin/pilot-agent proxy
    istio-p+  7094  4.0  0.3  69540 24800 ?        Sl   21:32   0:37 /usr/local/bin/envoy -c /etc/istio/proxy/envoy-rev1.json --restart-epoch 1 --drain-time-s 2 --parent-shutdown-time-s 3 --service-cluster istio-proxy --service-node sidecar~10.150.0.5~demo-vm-1.default~default.svc.cluster.local
    {{< /text >}}

*    Check the Envoy access and error logs:

    {{< text bash >}}
    $ tail /var/log/istio/istio.log
    $ tail /var/log/istio/istio.err.log
    {{< /text >}}
