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Set up VMs using manual Envoy deployment

This document is for network administrators who want to set up Traffic Director manually. However, we strongly recommend using automated Envoy deployment rather than the manual process that is described on this page.

Before you follow the instructions in this guide, review Prepare to set up Traffic Director with Envoy and make sure that you have completed the prerequisite tasks described in that document.

This guide shows you how to manually deploy a data plane that consists of Envoy sidecar proxies with Compute Engine virtual machines (VMs), configure it using Traffic Director, and verify your setup to ensure that it's functioning correctly. This process involves:

  1. Creating a test service.
  2. Deploying a simple data plane on Compute Engine using Envoy proxies.
  3. Setting up Traffic Director using Compute Engine APIs, which enable Traffic Director to configure your Envoy sidecar proxies.
  4. Log in to a VM that is running an Envoy proxy and send a request to a load-balanced backend through the Envoy proxy.

The configuration examples in this document are for demonstration purposes. For a production environment, you might need to deploy additional components, based on your environment and requirements.

Overview of the configuration process

This section provides the manual configuration process for services that run on Compute Engine VMs. The configuration process for the client VMs consists of setting up a sidecar proxy and traffic interception on a Compute Engine VM host. Then you configure load balancing using Google Cloud load balancing APIs.

This section provides information about how to obtain and inject Envoy proxies from third-party sources that are not managed by Google.

When an application sends traffic to the service configured in Traffic Director, the traffic is intercepted and redirected to the xDS API-compatible sidecar proxy and then load balanced to the backends according to the configuration in the GCP load balancing components. For more information on host networking and traffic interception, read Sidecar proxy traffic interception in Traffic Director.

For each VM host that requires access to Traffic Director services, perform the following steps:

  1. Assign a service account to the VM.

  2. Set the API access scope of the VM to allow full access to the Google Cloud APIs.

    • When you create the VMs, under Identity and API access, click Allow full access to all Cloud APIs.

      Go to the VM instances page.

    • With the gcloud CLI, specify the following:

      --scopes=https://www.googleapis.com/auth/cloud-platform.

  3. Allow outgoing connections to trafficdirector.googleapis.com (TCP, port 443) from the VM, so that the sidecar proxy can connect to the Traffic Director control plane over gRPC. Outgoing connections to port 443 are enabled by default.

  4. Deploy an xDS API-compatible sidecar proxy (such as Envoy), with a bootstrap configuration pointing to trafficdirector.googleapis.com:443 as its xDS server. Refer to this sample bootstrap configuration file as an example.

  5. Redirect IP traffic that is destined to the services to the sidecar proxy interception listener port.

Create the Hello World test service

This section shows you how to create a simple test service that returns the hostname of the VM that served the request from the client. The test service is uncomplicated; it's a web server deployed across a Compute Engine managed instance group.

Create the instance template

The instance template that you create configures a sample apache2 web server by using the startup-script parameter.

Console

  1. In the Google Cloud console, go to the Instance templates page.

    Go to Instance templates

  2. Click Create instance template.
  3. In the fields, enter the following information:
    • Name: td-demo-hello-world-template
    • Boot disk: Debian GNU/Linux 10 (buster)
    • Service account: Compute Engine default service account
    • Access scopes: Allow full access to all Cloud APIs
  4. Click Management, Security, Disks, Networking, Sole Tenancy.
  5. On the Networking tab, in the Network tags field, add the td-http-server tag.
  6. On the Management tab, copy the following script into the Startup script field.

    #! /bin/bash
    sudo apt-get update -y
    sudo apt-get install apache2 -y
    sudo service apache2 restart
    echo '<!doctype html><html><body><h1>'`/bin/hostname`'</h1></body></html>' | sudo tee /var/www/html/index.html
    
  7. Click Create.

gcloud

Create the instance template:

gcloud compute instance-templates create td-demo-hello-world-template \
  --machine-type=n1-standard-1 \
  --boot-disk-size=20GB \
  --image-family=debian-10 \
  --image-project=debian-cloud \
  --scopes=https://www.googleapis.com/auth/cloud-platform \
  --tags=td-http-server \
  --metadata=startup-script="#! /bin/bash
sudo apt-get update -y
sudo apt-get install apache2 -y
sudo service apache2 restart
sudo mkdir -p /var/www/html/
echo '<!doctype html><html><body><h1>'`/bin/hostname`'</h1></body></html>' | sudo tee /var/www/html/index.html"

Create the managed instance group

In this section, you specify that the managed instance group always has two instances of the test service. This is for demonstration purposes. Traffic Director supports autoscaled managed instance groups.

Console

  1. In the Google Cloud console, go to the Instance groups page.

    Go to Instance groups

  2. Click Create instance group.
  3. Select New managed instance group (stateless). For more information, see Stateless or stateful MIGs.
  4. Enter td-demo-hello-world-mig for the name for the managed instance group, and select the us-central1-a zone.
  5. Under Instance template, select td-demo-hello-world-template, which is the instance template you created.
  6. Under Autoscaling mode, select Don't autoscale.
  7. Under Number of instances, specify at least two as the number of instances that you want to create in the group.
  8. Click Create.

gcloud

Use the gcloud CLI to create a managed instance group with the instance template you previously created.

gcloud compute instance-groups managed create td-demo-hello-world-mig \
  --zone us-central1-a \
  --size=2 \
  --template=td-demo-hello-world-template

Create the instance template and managed instance group where Envoy is deployed

Use the instructions in this section to manually create an instance template and managed instance group for Traffic Director. Managed instance groups create new backend VMs by using autoscaling.

This example shows how to:

  • Create a VM template with a full Envoy configuration and a sample service that serves its hostname by using the HTTP protocol.
  • Configure a managed instance group using this template.

Create the instance template

First, create the Compute Engine VM instance template. This template auto-configures the Envoy sidecar proxy and sample apache2 web service through the startup-script parameter.

Console

  1. In the Google Cloud console, go to the Instance templates page.

    Go to Instance templates

  2. Click Create instance template.
  3. Fill in the fields as follows:

    • Name: td-vm-template
    • Boot disk: Debian GNU/Linux 10 (buster)
    • Service account: Compute Engine default service account
    • Access scopes: Allow full access to all Cloud APIs
  4. Under Firewall, select the boxes next to Allow HTTP traffic and Allow HTTPS traffic.

  5. Click Management, Security, Disks, Networking, Sole Tenancy.

  6. On the Management tab, copy the following script into the Startup script field.

    #! /usr/bin/env bash
    
    # Set variables
    export ENVOY_USER="envoy"
    export ENVOY_USER_UID="1337"
    export ENVOY_USER_GID="1337"
    export ENVOY_USER_HOME="/opt/envoy"
    export ENVOY_CONFIG="${ENVOY_USER_HOME}/config.yaml"
    export ENVOY_PORT="15001"
    export ENVOY_ADMIN_PORT="15000"
    export ENVOY_TRACING_ENABLED="false"
    export ENVOY_XDS_SERVER_CERT="/etc/ssl/certs/ca-certificates.crt"
    export ENVOY_ACCESS_LOG="/dev/stdout"
    export ENVOY_NODE_ID="$(cat /proc/sys/kernel/random/uuid)~$(hostname -i)"
    export BOOTSTRAP_TEMPLATE="${ENVOY_USER_HOME}/bootstrap_template.yaml"
    export GCE_METADATA_SERVER="169.254.169.254/32"
    export INTERCEPTED_CIDRS="*"
    export GCP_PROJECT_NUMBER=PROJECT_NUMBER
    export VPC_NETWORK_NAME=NETWORK_NAME
    export GCE_ZONE=$(curl -sS -H "Metadata-Flavor: Google" http://metadata.google.internal/computeMetadata/v1/instance/zone | cut -d"/" -f4)
    
    # Create system user account for Envoy binary
    sudo groupadd ${ENVOY_USER} \
     --gid=${ENVOY_USER_GID} \
     --system
    sudo adduser ${ENVOY_USER} \
     --uid=${ENVOY_USER_UID} \
     --gid=${ENVOY_USER_GID} \
     --home=${ENVOY_USER_HOME} \
     --disabled-login \
     --system
    
    # Download and extract the Traffic Director tar.gz file
    cd ${ENVOY_USER_HOME}
    sudo curl -sL https://storage.googleapis.com/traffic-director/traffic-director-xdsv3.tar.gz -o traffic-director-xdsv3.tar.gz
    sudo tar -xvzf traffic-director-xdsv3.tar.gz traffic-director-xdsv3/bootstrap_template.yaml \
     -C bootstrap_template.yaml \
     --strip-components 1
    sudo tar -xvzf traffic-director-xdsv3.tar.gz traffic-director-xdsv3/iptables.sh \
     -C iptables.sh \
     --strip-components 1
    sudo rm traffic-director-xdsv3.tar.gz
    
    # Generate Envoy bootstrap configuration
    cat "${BOOTSTRAP_TEMPLATE}" \
     | sed -e "s|ENVOY_NODE_ID|${ENVOY_NODE_ID}|g" \
     | sed -e "s|ENVOY_ZONE|${GCE_ZONE}|g" \
     | sed -e "s|VPC_NETWORK_NAME|${VPC_NETWORK_NAME}|g" \
     | sed -e "s|CONFIG_PROJECT_NUMBER|${GCP_PROJECT_NUMBER}|g" \
     | sed -e "s|ENVOY_PORT|${ENVOY_PORT}|g" \
     | sed -e "s|ENVOY_ADMIN_PORT|${ENVOY_ADMIN_PORT}|g" \
     | sed -e "s|XDS_SERVER_CERT|${ENVOY_XDS_SERVER_CERT}|g" \
     | sed -e "s|TRACING_ENABLED|${ENVOY_TRACING_ENABLED}|g" \
     | sed -e "s|ACCESSLOG_PATH|${ENVOY_ACCESS_LOG}|g" \
     | sed -e "s|BACKEND_INBOUND_PORTS|${BACKEND_INBOUND_PORTS}|g" \
     | sudo tee "${ENVOY_CONFIG}"
    
    # Install Envoy binary
    curl -sL "https://deb.dl.getenvoy.io/public/gpg.8115BA8E629CC074.key" | sudo gpg --dearmor -o /usr/share/keyrings/getenvoy-keyring.gpg
    echo a077cb587a1b622e03aa4bf2f3689de14658a9497a9af2c427bba5f4cc3c4723 /usr/share/keyrings/getenvoy-keyring.gpg | sha256sum --check
    echo "deb [arch=amd64 signed-by=/usr/share/keyrings/getenvoy-keyring.gpg] https://deb.dl.getenvoy.io/public/deb/debian $(lsb_release -cs) main" | sudo tee /etc/apt/sources.list.d/getenvoy.list
    sudo apt update
    sudo apt -y install getenvoy-envoy
    
    # Run Envoy as systemd service
    sudo systemd-run --uid=${ENVOY_USER_UID} --gid=${ENVOY_USER_GID} \
     --working-directory=${ENVOY_USER_HOME} --unit=envoy.service \
     bash -c "/usr/bin/envoy --config-path ${ENVOY_CONFIG} | tee"
    
    # Configure iptables for traffic interception and redirection
    sudo ${ENVOY_USER_HOME}/iptables.sh \
     -p "${ENVOY_PORT}" \
     -u "${ENVOY_USER_UID}" \
     -g "${ENVOY_USER_GID}" \
     -m "REDIRECT" \
     -i "${INTERCEPTED_CIDRS}" \
     -x "${GCE_METADATA_SERVER}"
    
  7. Click Create to create the template.

gcloud

Create the instance template.

gcloud compute instance-templates create td-vm-template \
  --scopes=https://www.googleapis.com/auth/cloud-platform \
  --tags=http-td-tag,http-server,https-server \
  --image-family=debian-10 \
  --image-project=debian-cloud \
  --metadata=startup-script='#! /usr/bin/env bash

# Set variables
export ENVOY_USER="envoy"
export ENVOY_USER_UID="1337"
export ENVOY_USER_GID="1337"
export ENVOY_USER_HOME="/opt/envoy"
export ENVOY_CONFIG="${ENVOY_USER_HOME}/config.yaml"
export ENVOY_PORT="15001"
export ENVOY_ADMIN_PORT="15000"
export ENVOY_TRACING_ENABLED="false"
export ENVOY_XDS_SERVER_CERT="/etc/ssl/certs/ca-certificates.crt"
export ENVOY_ACCESS_LOG="/dev/stdout"
export ENVOY_NODE_ID="$(cat /proc/sys/kernel/random/uuid)~$(hostname -i)"
export BOOTSTRAP_TEMPLATE="${ENVOY_USER_HOME}/bootstrap_template.yaml"
export GCE_METADATA_SERVER="169.254.169.254/32"
export INTERCEPTED_CIDRS="*"
export GCP_PROJECT_NUMBER=PROJECT_NUMBER
export VPC_NETWORK_NAME=NETWORK_NAME
export GCE_ZONE=$(curl -sS -H "Metadata-Flavor: Google" http://metadata.google.internal/computeMetadata/v1/instance/zone | cut -d"/" -f4)

# Create system user account for Envoy binary
sudo groupadd ${ENVOY_USER} \
  --gid=${ENVOY_USER_GID} \
  --system
sudo adduser ${ENVOY_USER} \
  --uid=${ENVOY_USER_UID} \
  --gid=${ENVOY_USER_GID} \
  --home=${ENVOY_USER_HOME} \
  --disabled-login \
  --system
# Download and extract the Traffic Director tar.gz file
cd ${ENVOY_USER_HOME}
sudo curl -sL https://storage.googleapis.com/traffic-director/traffic-director-xdsv3.tar.gz -o traffic-director-xdsv3.tar.gz
sudo tar -xvzf traffic-director-xdsv3.tar.gz traffic-director-xdsv3/bootstrap_template.yaml \
  -C bootstrap_template.yaml \
  --strip-components 1
sudo tar -xvzf traffic-director-xdsv3.tar.gz traffic-director-xdsv3/iptables.sh \
  -C iptables.sh \
  --strip-components 1
sudo rm traffic-director-xdsv3.tar.gz

# Generate Envoy bootstrap configuration
cat "${BOOTSTRAP_TEMPLATE}" \
  | sed -e "s|ENVOY_NODE_ID|${ENVOY_NODE_ID}|g" \
  | sed -e "s|ENVOY_ZONE|${GCE_ZONE}|g" \
  | sed -e "s|VPC_NETWORK_NAME|${VPC_NETWORK_NAME}|g" \
  | sed -e "s|CONFIG_PROJECT_NUMBER|${GCP_PROJECT_NUMBER}|g" \
  | sed -e "s|ENVOY_PORT|${ENVOY_PORT}|g" \
  | sed -e "s|ENVOY_ADMIN_PORT|${ENVOY_ADMIN_PORT}|g" \
  | sed -e "s|XDS_SERVER_CERT|${ENVOY_XDS_SERVER_CERT}|g" \
  | sed -e "s|TRACING_ENABLED|${ENVOY_TRACING_ENABLED}|g" \
  | sed -e "s|ACCESSLOG_PATH|${ENVOY_ACCESS_LOG}|g" \
  | sed -e "s|BACKEND_INBOUND_PORTS|${BACKEND_INBOUND_PORTS}|g" \
  | sudo tee "${ENVOY_CONFIG}"

# Install Envoy binary
curl -sL "https://deb.dl.getenvoy.io/public/gpg.8115BA8E629CC074.key" | sudo gpg --dearmor -o /usr/share/keyrings/getenvoy-keyring.gpg
echo a077cb587a1b622e03aa4bf2f3689de14658a9497a9af2c427bba5f4cc3c4723 /usr/share/keyrings/getenvoy-keyring.gpg | sha256sum --check
echo "deb [arch=amd64 signed-by=/usr/share/keyrings/getenvoy-keyring.gpg] https://deb.dl.getenvoy.io/public/deb/debian $(lsb_release -cs) main" | sudo tee /etc/apt/sources.list.d/getenvoy.list
sudo apt update
sudo apt -y install getenvoy-envoy

# Run Envoy as systemd service
sudo systemd-run --uid=${ENVOY_USER_UID} --gid=${ENVOY_USER_GID} \
  --working-directory=${ENVOY_USER_HOME} --unit=envoy.service \
  bash -c "/usr/bin/envoy --config-path ${ENVOY_CONFIG} | tee"

# Configure iptables for traffic interception and redirection
sudo ${ENVOY_USER_HOME}/iptables.sh \
  -p "${ENVOY_PORT}" \
  -u "${ENVOY_USER_UID}" \
  -g "${ENVOY_USER_GID}" \
  -m "REDIRECT" \
  -i "${INTERCEPTED_CIDRS}" \
  -x "${GCE_METADATA_SERVER}"
'

Create the managed instance group

If you don't have a managed instance group with services running, create a managed instance group, using a VM template such as the one shown in the previous section. This example uses the instance template created in the previous section to demonstrate functionality. You do not have to use the instance template.

Console

  1. In the Google Cloud console, go to the Instance groups page.

    Go to Instance groups

  2. Click Create an instance group. By default, you see the page for creating a managed instance group.
  3. Choose New managed instance group (stateless). For more information, see Stateless or stateful MIGs.
  4. Enter td-vm-mig-us-central1 for the name for the managed instance group, and select the us-central1-a zone.
  5. Under Instance template, select the instance template you created.
  6. Specify 2 as the number of instances that you want to create in the group.
  7. Click Create.

gcloud

Use the gcloud CLI to create a managed instance group with the instance template you previously created.

gcloud compute instance-groups managed create td-vm-mig-us-central1 \
    --zone us-central1-a --size=2 --template=td-vm-template

Configure Traffic Director with Google Cloud load balancing components

The instructions in this section show you how to configure Traffic Director so that your Envoy proxies load balance outbound traffic across two backend instances. You configure the following components:

Create the health check

Use the following instructions to create a health check. For more information, refer to Create health checks.

Console

  1. In the Google Cloud console, go to the Health checks page.

    Go to Health checks

  2. Click Create health check.
  3. For the name, enter td-vm-health-check.
  4. For the protocol, select HTTP.
  5. Click Create.

gcloud

  1. Create the health check:

    gcloud compute health-checks create http td-vm-health-check
    
  2. Create the firewall rule:

    gcloud compute firewall-rules create fw-allow-health-checks \
      --action ALLOW \
      --direction INGRESS \
      --source-ranges 35.191.0.0/16,130.211.0.0/22 \
      --target-tags http-td-tag,http-server,https-server \
      --rules tcp
    

Create the backend service

If you use the Google Cloud CLI, you must designate the backend service as a global backend service with a load balancing scheme of INTERNAL_SELF_MANAGED. Add the health check and a managed or unmanaged instance group to the backend service. Note that this example uses the managed instance group with Compute Engine VM template that runs the sample HTTP service created in Create the managed instance group.

Console

  1. In the Google Cloud console, go to the Traffic Director page.

    Go to Traffic Director

  2. On the Services tab, click Create Service.
  3. Click Continue.
  4. For the service name, enter td-vm-service.
  5. Select the correct VPC network.
  6. Ensure that the Backend type is Instance groups.
  7. Select the managed instance group you created.
  8. Enter the correct Port numbers.
  9. Choose Utilization or Rate as the Balancing mode. The default value is Rate.
  10. Click Done.
  11. Select the health check you created.
  12. Click Save and continue.
  13. Click Create.

gcloud

  1. Create the backend service:

    gcloud compute backend-services create td-vm-service \
      --global \
      --load-balancing-scheme=INTERNAL_SELF_MANAGED \
      --health-checks td-vm-health-check
    
  2. Add the backends to the backend service:

    gcloud compute backend-services add-backend td-vm-service \
       --instance-group td-vm-mig-us-central1 \
       --instance-group-zone us-central1-a \
       --global
    

Create the routing rule map

The routing rule map defines how Traffic Director routes traffic in your mesh.

Use these instructions to create the route rule, forwarding rule, target proxy, and internal IP address for your Traffic Director configuration.

Traffic sent to the internal IP address is intercepted by the Envoy proxy and sent to the appropriate service according to the host and path rules.

The forwarding rule is created as a global forwarding rule with the load-balancing-scheme set to INTERNAL_SELF_MANAGED.

You can set the address of your forwarding rule to 0.0.0.0. If you do, traffic is routed based on the HTTP hostname and path information configured in the URL map, regardless of the actual destination IP address of the request. In this case, the hostnames of your services, as configured in the host rules, must be unique within your service mesh configuration. That is, you cannot have two different services, with different sets of backends, that both use the same hostname.

Alternatively, you can enable routing based on the actual destination VIP of the service. If you configure the VIP of your service as an address parameter of the forwarding rule, only requests destined to this address are routed based on the HTTP parameters specified in the URL map.

This example uses 10.0.0.1 as the address parameter, meaning that routing for your service is performed based on the actual destination VIP of the service.

Console

In the Google Cloud console, the target proxy is combined with the forwarding rule. When you create the forwarding rule, Google Cloud automatically creates a target HTTP proxy and attaches it to the URL map.

  1. In the Google Cloud console, go to the Traffic Director page.

    Go to Traffic Director

  2. On the Routing rule maps tab, click Create Routing Rule Map.
  3. Enter a name.
  4. Click Add Forwarding Rule.
  5. For the forwarding rule name, enter td-vm-forwarding-rule.
  6. Select your network.
  7. Select your Internal IP. Traffic sent to this IP address is intercepted by the Envoy proxy and sent to the appropriate service according to the host and path rules.

    The forwarding rule is created as a global forwarding rule with the load-balancing-scheme set to INTERNAL_SELF_MANAGED.

  8. In the Custom IP field, type 10.0.0.1. When your VM sends to this IP address, the Envoy proxy intercepts it and sends it to the appropriate backend service's endpoint according to the traffic management rules defined in the URL map.

    Each forwarding rule in a VPC network must have a unique IP address and port per VPC network. If you create more than one forwarding rule with the same IP address and port in a particular VPC network, only the first forwarding rule is valid. Others are ignored. If 10.0.0.1 is not available in your network, choose a different IP address.

  9. Make sure that the Port is set to 80.

  10. Click Save.

  11. In the Routing rules section, select Simple host and path rule.

  12. In the Host and path rules section, select td-vm-service as the Service.

  13. Click Add host and path rule.

  14. In Hosts, enter hello-world.

  15. In Service, select td-vm-service.

  16. Click Save.

gcloud

  1. Create a URL map that uses the backend service:

    gcloud compute url-maps create td-vm-url-map \
       --default-service td-vm-service
    
  2. Create a URL map path matcher and a host rule to route traffic for your service based on hostname and a path. This example uses service-test as the service name and a default path matcher that matches all path requests for this host (/*).

    gcloud compute url-maps add-path-matcher td-vm-url-map \
       --default-service td-vm-service --path-matcher-name td-vm-path-matcher
    
    gcloud compute url-maps add-host-rule td-vm-url-map --hosts service-test \
       --path-matcher-name td-vm-path-matcher \
       --hosts hello-world
    
  3. Create the target HTTP proxy:

    gcloud compute target-http-proxies create td-vm-proxy \
       --url-map td-vm-url-map
    
  4. Create the forwarding rule. The forwarding rule must be global and must be created with the value of load-balancing-scheme set to INTERNAL_SELF_MANAGED.

    gcloud compute forwarding-rules create td-vm-forwarding-rule \
       --global \
       --load-balancing-scheme=INTERNAL_SELF_MANAGED \
       --address=10.0.0.1 \
       --target-http-proxy=td-vm-proxy \
       --ports 80 \
       --network default
    

At this point, Traffic Director is configured to load balance traffic for the services specified in the URL map across backends in the managed instance group.

Verify the configuration

In this final portion of the Traffic Director setup guide for Compute Engine VMs, you test that traffic sent from the client VM destined to the forwarding rule VIP is intercepted and redirected to the Envoy proxy, which then routes your request to the VMs hosting the Hello World service.

First, verify that the backends are healthy by using the following steps:

Console

  1. In the Google Cloud console, go to the Traffic Director page.

    Go to Traffic Director

    The Summary tells you whether the services are healthy.

  2. Click the name of a service. The Service details page has information about the health of the backends.
  3. If the backends are unhealthy, you can reset them by clicking the name of the backends and then clicking Reset on the VM instance details page.

gcloud

Use the compute backend-services get-health command to verify that the backends are healthy:

gcloud compute backend-services get-health td-vm-service \
    --global \
    --format=get(name, healthStatus)

After verifying the health states of your backends, log into the client VM that has been configured to intercept traffic and redirect it to Envoy. Send a curl request to the VIP associated with your routing rule map. Envoy inspects the curl request, determines which service it should resolve to, and sends the request to a backend associated with that service.

Console

  1. In the Google Cloud console, go to the Instance groups page.

    Go to Instance groups

  2. Select the td-vm-mig-us-central1 instance group.
  3. Under Connect, click SSH.
  4. After you are logged in to the client VM, use the curl tool to send a request to the Hello World service through Envoy:

    curl -H "Host: hello-world" http://10.0.0.1/
    

When you issue this command repeatedly, you will see different HTML responses containing the hostnames of backends in the Hello World managed instance group. This is because Envoy is using round robin load balancing, the default load balancing algorithm, when sending traffic to the Hello World service's backends.

When the configuration is complete, each Compute Engine VM that has a sidecar proxy can access services configured in Traffic Director using the HTTP protocol.

If you followed the specific examples in this guide by using the Compute Engine VM template with the demonstration HTTP server and service hostname service-test, use these steps to verify the configuration:

  1. Log in to one of the VM hosts that has a sidecar proxy installed.
  2. Execute the command curl -H 'Host: service-test' 10.0.0.1. This request returns the hostname of the managed instance group backend that served the request.

In step 2, note that you can use any IP address. For example, the command curl -I -H 'Host: service-test' 1.2.3.4 would work in Step 2.

This is because the forwarding rule has the address parameter set to 0.0.0.0, which instructs Traffic Director to match based on the host defined in the URL map. In the example configuration, the host name is service-test.

What's next