Set up a regional external Application Load Balancer with VM instance group backends

This document provides instructions for configuring a regional external Application Load Balancer for your services that run on Compute Engine VMs.

Because regional external Application Load Balancers allow you to create load balancers in specific regions, they are often used for workloads that have jurisdictional compliance requirements. Workloads that require access to Standard Network Tier egress are another common use case for regional external Application Load Balancers, because the regional external Application Load Balancers support the Standard Network Service Tier.

Before following this guide, familiarize yourself with the following:

Permissions

To follow this guide, you must be able to create instances and modify a network in a project. You must be either a project owner or editor, or you must have all of the following Compute Engine IAM roles.

Task Required role
Create networks, subnets, and load balancer components Network Admin
Add and remove firewall rules Security Admin
Create instances Instance Admin

For more information, see the following guides:

Setup overview

You can configure a regional external Application Load Balancer as described in the following high-level configuration flow. The numbered steps refer to the numbers in the diagram.

Regional external Application Load Balancer numbered components (click to enlarge)
Regional external Application Load Balancer numbered components (click to enlarge)

As shown in the diagram, this example creates a regional external Application Load Balancer in a VPC network in region us-west1, with one backend service and two backend instance groups.

The diagram shows the following:

  1. A VPC network with two subnets:

    1. One subnet is used for backends (instance groups). Its primary IP address range is 10.1.2.0/24.

    2. One subnet is a proxy-only subnet in the us-west1 region. You must create one proxy-only subnet in each region of a VPC network where you use regional external Application Load Balancers. The region's proxy-only subnet is shared among all regional load balancers in the region. Source addresses of packets sent from the load balancers to your service's backends are allocated from the proxy-only subnet. In this example, the proxy-only subnet for the region has a primary IP address range of 10.129.0.0/23, which is the recommended subnet size. For more information, see Proxy-only subnets.

  2. A firewall rule that permits proxy-only subnet traffic flows in your network. This means adding one rule that allows TCP port 80, 443, and 8080 traffic from 10.129.0.0/23 (the range of the proxy-only subnet in this example). Another firewall rule for the health check probes.

  3. Backend instances.

  4. Instance groups:

    1. Managed or unmanaged instance groups for Compute Engine VM deployments
    2. NEGs for GKE deployments

    In each zone, you can have a combination of backend group types based on the requirements of your deployment.

  5. A regional health check that reports the readiness of your backends.

  6. A regional backend service that monitors the usage and health of backends.

  7. A regional URL map that parses the URL of a request and forwards requests to specific backend services based on the host and path of the request URL.

  8. A regional target HTTP or HTTPS proxy, which receives a request from the user and forwards it to the URL map. For HTTPS, configure a regional SSL certificate resource. The target proxy uses the SSL certificate to decrypt SSL traffic if you configure HTTPS load balancing. The target proxy can forward traffic to your instances by using HTTP or HTTPS.

  9. A forwarding rule, which has the external IP address of your load balancer to forward each incoming request to the target proxy.

    The external IP address that is associated with the forwarding rule is reserved by using the gcloud compute addresses create command, as described in Reserving the load balancer's IP address.

Configure the network and subnets

You need a VPC network with two subnets: one for the load balancer's backends and the other for the load balancer's proxies. A regional external Application Load Balancer is regional. Traffic within the VPC network is routed to the load balancer if the traffic's source is in a subnet in the same region as the load balancer.

This example uses the following VPC network, region, and subnets:

  • Network. The network is a custom-mode VPC network named lb-network.

  • Subnet for backends. A subnet named backend-subnet in the us-west1 region uses 10.1.2.0/24 for its primary IP range.

  • Subnet for proxies. A subnet named proxy-only-subnet in the us-west1 region uses 10.129.0.0/23 for its primary IP range.

Configure the network and subnet for backends

Console

  1. In the Google Cloud console, go to the VPC networks page.

    Go to VPC networks

  2. Click Create VPC network.

  3. For Name, enter lb-network.

  4. In the Subnets section:

    • Set Subnet creation mode to Custom.
    • In the New subnet section, enter the following information:
      • Name: backend-subnet
      • Region: us-west1
      • IP address range: 10.1.2.0/24
    • Click Done.

  5. Click Create.

gcloud

  1. Create the custom VPC network with the gcloud compute networks create command:

    gcloud compute networks create lb-network --subnet-mode=custom

  2. Create a subnet in the lb-network network in the us-west1 region with the gcloud compute networks subnets create command:

    gcloud compute networks subnets create backend-subnet \
    --network=lb-network \
    --range=10.1.2.0/24 \
    --region=us-west1

Terraform

To create the VPC network, use the google_compute_network resource.

lb/regional_external_http_load_balancer/main.tf 
resource "google_compute_network" "default" {
  name                    = "lb-network"
  auto_create_subnetworks = false
  routing_mode            = "REGIONAL"
}

To create the VPC subnet in the lb-network network, use the google_compute_subnetwork resource.

lb/regional_external_http_load_balancer/main.tf 
resource "google_compute_subnetwork" "default" {
  name                       = "backend-subnet"
  ip_cidr_range              = "10.1.2.0/24"
  network                    = google_compute_network.default.id
  private_ipv6_google_access = "DISABLE_GOOGLE_ACCESS"
  purpose                    = "PRIVATE"
  region                     = "us-west1"
  stack_type                 = "IPV4_ONLY"
}

API

  1. Make a POST request to the networks.insert method, replacing PROJECT_ID with your project ID.

    POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/global/networks
{
 "routingConfig": {
   "routingMode": "REGIONAL"
 },
 "name": "lb-network",
 "autoCreateSubnetworks": false
}

  2. Make a POST request to the subnetworks.insert method, replacing PROJECT_ID with your project ID.

    POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/regions/us-west1/subnetworks
{
 "name": "backend-subnet",
 "network": "projects/PROJECT_ID/global/networks/lb-network",
 "ipCidrRange": "10.1.2.0/24",
 "region": "projects/PROJECT_ID/regions/us-west1",
}

Configure the proxy-only subnet

A proxy-only subnet provides a set of IP addresses that Google uses to run Envoy proxies on your behalf. The proxies terminate connections from the client and create new connections to the backends.

This proxy-only subnet is used by all Envoy-based regional load balancers in the same region of the lb-network VPC network. There can only be one active proxy-only subnet per region, per network.

Console

If you're using the Google Cloud console, you can also wait and create the proxy-only subnet later on the Load balancing page.

If you want to create the proxy-only subnet now, use the following steps:

  1. In the Google Cloud console, go to the VPC networks page.

    Go to VPC networks

  2. Click the name of the VPC network: lb-network.

  3. Click Add subnet.

  4. For Name, enter proxy-only-subnet.

  5. For Region, select us-west1.

  6. Set Purpose to Regional Managed Proxy.

  7. For IP address range, enter 10.129.0.0/23.

  8. Click Add.

gcloud

Create the proxy-only subnet with the gcloud compute networks subnets create command.

gcloud compute networks subnets create proxy-only-subnet \
  --purpose=REGIONAL_MANAGED_PROXY \
  --role=ACTIVE \
  --region=us-west1 \
  --network=lb-network \
  --range=10.129.0.0/23

Terraform

To create the VPC proxy-only subnet in the lb-network network, use the google_compute_subnetwork resource.

lb/regional_external_http_load_balancer/main.tf 
resource "google_compute_subnetwork" "proxy_only" {
  name          = "proxy-only-subnet"
  ip_cidr_range = "10.129.0.0/23"
  network       = google_compute_network.default.id
  purpose       = "REGIONAL_MANAGED_PROXY"
  region        = "us-west1"
  role          = "ACTIVE"
}

API

Create the proxy-only subnet with the subnetworks.insert method, replacing PROJECT_ID with your project ID.

POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/regions/us-west1/subnetworks
{
  "name": "proxy-only-subnet",
  "ipCidrRange": "10.129.0.0/23",
  "network": "projects/PROJECT_ID/global/networks/lb-network",
  "region": "projects/PROJECT_ID/regions/us-west1",
  "purpose": "REGIONAL_MANAGED_PROXY",
  "role": "ACTIVE"
}

Configure firewall rules

This example uses the following firewall rules:

  • fw-allow-health-check. An ingress rule, applicable to the instances being load balanced, that allows all TCP traffic from the Google Cloud health checking systems (in 130.211.0.0/22 and 35.191.0.0/16). This example uses the target tag load-balanced-backend to identify the VMs that the firewall rule applies to.

  • fw-allow-proxies. An ingress rule, applicable to the instances being load balanced, that allows TCP traffic on ports 80, 443, and 8080 from the regional external Application Load Balancer's managed proxies. This example uses the target tag load-balanced-backend to identify the VMs that the firewall rule applies to.

Without these firewall rules, the default deny ingress rule blocks incoming traffic to the backend instances.

The target tags define the backend instances. Without the target tags, the firewall rules apply to all of your backend instances in the VPC network. When you create the backend VMs, make sure to include the specified target tags, as shown in Creating a managed instance group.

Console

  1. In the Google Cloud console, go to the Firewall policies page.

    Go to Firewall rules

  2. Click Create firewall rule to create the rule to allow Google Cloud health checks:

    • Name: fw-allow-health-check
    • Network: lb-network
    • Direction of traffic: Ingress
    • Action on match: Allow
    • Targets: Specified target tags
    • Target tags: load-balanced-backend
    • Source filter: IPv4 ranges
    • Source IPv4 ranges: 130.211.0.0/22 and 35.191.0.0/16
    • Protocols and ports:
      • Choose Specified protocols and ports.
      • Select the TCP checkbox, and then enter 80 for the port number.
        As a best practice, limit this rule to just the protocols and ports that match those used by your health check. If you use tcp:80 for the protocol and port, Google Cloud can use HTTP on port 80 to contact your VMs, but it cannot use HTTPS on port 443 to contact them.

  3. Click Create.

  4. Click Create firewall rule to create the rule to allow the load balancer's proxy servers to connect the backends:

    • Name: fw-allow-proxies
    • Network: lb-network
    • Direction of traffic: Ingress
    • Action on match: Allow
    • Targets: Specified target tags
    • Target tags: load-balanced-backend
    • Source filter: IPv4 ranges
    • Source IPv4 ranges: 10.129.0.0/23
    • Protocols and ports:
      • Choose Specified protocols and ports.
      • Select the TCP checkbox, and then enter 80, 443, 8080 for the port numbers.

  5. Click Create.

gcloud

  1. Create the fw-allow-health-check rule to allow Google Cloud health checks. This example allows all TCP traffic from health check probers; however, you can configure a narrower set of ports to meet your needs.

    gcloud compute firewall-rules create fw-allow-health-check \
    --network=lb-network \
    --action=allow \
    --direction=ingress \
    --source-ranges=130.211.0.0/22,35.191.0.0/16 \
    --target-tags=load-balanced-backend \
    --rules=tcp

  2. Create the fw-allow-proxies rule to allow the regional external Application Load Balancer's proxies to connect to your backends. Set source-ranges to the allocated ranges of your proxy-only subnet, for example, 10.129.0.0/23.

    gcloud compute firewall-rules create fw-allow-proxies \
  --network=lb-network \
  --action=allow \
  --direction=ingress \
  --source-ranges=source-range \
  --target-tags=load-balanced-backend \
  --rules=tcp:80,tcp:443,tcp:8080

Terraform

To create the firewall rules, use the google_compute_firewall resource.

lb/regional_external_http_load_balancer/main.tf 
resource "google_compute_firewall" "default" {
  name = "fw-allow-health-check"
  allow {
    protocol = "tcp"
  }
  direction     = "INGRESS"
  network       = google_compute_network.default.id
  priority      = 1000
  source_ranges = ["130.211.0.0/22", "35.191.0.0/16"]
  target_tags   = ["load-balanced-backend"]
}
lb/regional_external_http_load_balancer/main.tf 
resource "google_compute_firewall" "allow_proxy" {
  name = "fw-allow-proxies"
  allow {
    ports    = ["443"]
    protocol = "tcp"
  }
  allow {
    ports    = ["80"]
    protocol = "tcp"
  }
  allow {
    ports    = ["8080"]
    protocol = "tcp"
  }
  direction     = "INGRESS"
  network       = google_compute_network.default.id
  priority      = 1000
  source_ranges = ["10.129.0.0/23"]
  target_tags   = ["load-balanced-backend"]
}

API

Create the fw-allow-health-check firewall rule by making a POST request to the firewalls.insert method, replacing PROJECT_ID with your project ID.

POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/global/firewalls
{
  "name": "fw-allow-health-check",
  "network": "projects/PROJECT-ID/global/networks/lb-network",
  "sourceRanges": [
    "130.211.0.0/22",
    "35.191.0.0/16"
  ],
  "targetTags": [
    "load-balanced-backend"
  ],
  "allowed": [
    {
      "IPProtocol": "tcp"
    }
  ],
  "direction": "INGRESS"
}

Create the fw-allow-proxies firewall rule to allow TCP traffic within the proxy subnet for the firewalls.insert method, replacing PROJECT_ID with your project ID.

POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/global/firewalls
{
  "name": "fw-allow-proxies",
  "network": "projects/PROJECT_ID/global/networks/lb-network",
  "sourceRanges": [
    "10.129.0.0/23"
  ],
  "targetTags": [
    "load-balanced-backend"
  ],
  "allowed": [
    {
      "IPProtocol": "tcp",
      "ports": [
        "80"
      ]
    },
    {
      "IPProtocol": "tcp",
      "ports": [
        "443"
      ]
    },
    {
      "IPProtocol": "tcp",
      "ports": [
        "8080"
      ]
    }
  ],
  "direction": "INGRESS"
}

Configure a regional external Application Load Balancer with a VM-based service

This section shows the configuration required for services that run on Compute Engine VMs. Client VMs connect to the IP address and port that you configure in the forwarding rule. When your client applications send traffic to this IP address and port, their requests are forwarded to your backend virtual machines (VMs) according to your regional external Application Load Balancer's URL map.

The example on this page explicitly creates a reserved external IP address for the regional external Application Load Balancer's forwarding rule, rather than allowing an ephemeral external IP address to be allocated. As a best practice, we recommend reserving IP addresses for forwarding rules.

Create a managed instance group backend

This section shows how to create a template and a managed instance group. The managed instance group provides VM instances running the backend servers of an example regional external Application Load Balancer. Traffic from clients is load balanced to these backend servers. For demonstration purposes, backends serve their own hostnames.

Console

  1. Create an instance template. In the Google Cloud console, go to the Instance templates page.

    Go to Instance templates

    1. Click Create instance template.
    2. For Name, enter l7-xlb-backend-template.
    3. Ensure that Boot disk is set to a Debian image, such as Debian GNU/Linux 10 (buster). These instructions use commands that are only available on Debian, such as apt-get.
    4. Click Advanced options.
    5. Click Networking and configure the following fields:
      1. For Network tags, enter load-balanced-backend.
      2. For Network interfaces, select the following:
        • Network: lb-network
        • Subnet: backend-subnet

    6. Click Management. Enter the following script into the Startup script field.

      #! /bin/bash
apt-get update
apt-get install apache2 -y
a2ensite default-ssl
a2enmod ssl
vm_hostname="$(curl -H "Metadata-Flavor:Google" \
http://metadata.google.internal/computeMetadata/v1/instance/name)"
echo "Page served from: $vm_hostname" | \
tee /var/www/html/index.html
systemctl restart apache2

    7. Click Create.

  2. Create a managed instance group. In the Google Cloud console, go to the Instance groups page.

    Go to Instance groups

    1. Click Create instance group.
    2. Select New managed instance group (stateless). For more information, see Stateless or stateful MIGs.
    3. For Name, enter l7-xlb-backend-example.
    4. For Location, select Single zone.
    5. For Region, select us-west1.
    6. For Zone, select us-west1-a.
    7. For Instance template, select l7-xlb-backend-template.

    8. For Autoscaling mode, select On: add and remove instances to the group.

      Set Minimum number of instances to 2, and set Maximum number of instances to 2 or more.

    9. Click Create.

gcloud

The gcloud instructions in this guide assume that you are using Cloud Shell or another environment with bash installed.

  1. Create a VM instance template with HTTP server with the gcloud compute instance-templates create command.

    gcloud compute instance-templates create l7-xlb-backend-template \
--region=us-west1 \
--network=lb-network \
--subnet=backend-subnet \
--tags=load-balanced-backend \
--image-family=debian-10 \
--image-project=debian-cloud \
--metadata=startup-script='#! /bin/bash
apt-get update
apt-get install apache2 -y
a2ensite default-ssl
a2enmod ssl
vm_hostname="$(curl -H "Metadata-Flavor:Google" \
http://metadata.google.internal/computeMetadata/v1/instance/name)"
echo "Page served from: $vm_hostname" | \
tee /var/www/html/index.html
systemctl restart apache2'

  2. Create a managed instance group in the zone with the gcloud compute instance-groups managed create command.

    gcloud compute instance-groups managed create l7-xlb-backend-example \
    --zone=us-west1-a \
    --size=2 \
    --template=l7-xlb-backend-template

Terraform

To create the instance template, use the google_compute_instance_template resource.

lb/regional_external_http_load_balancer/main.tf 
resource "google_compute_instance_template" "default" {
  name = "l7-xlb-backend-template"
  disk {
    auto_delete  = true
    boot         = true
    device_name  = "persistent-disk-0"
    mode         = "READ_WRITE"
    source_image = "projects/debian-cloud/global/images/family/debian-10"
    type         = "PERSISTENT"
  }
  labels = {
    managed-by-cnrm = "true"
  }
  machine_type = "n1-standard-1"
  metadata = {
    startup-script = <<EOF
    #! /bin/bash
    sudo apt-get update
    sudo apt-get install apache2 -y
    sudo a2ensite default-ssl
    sudo a2enmod ssl
    vm_hostname="$(curl -H "Metadata-Flavor:Google" \
    http://169.254.169.254/computeMetadata/v1/instance/name)"
    sudo echo "Page served from: $vm_hostname" | \
    tee /var/www/html/index.html
    sudo systemctl restart apache2
    EOF
  }
  network_interface {
    access_config {
      network_tier = "PREMIUM"
    }
    network    = google_compute_network.default.id
    subnetwork = google_compute_subnetwork.default.id
  }
  region = "us-west1"
  scheduling {
    automatic_restart   = true
    on_host_maintenance = "MIGRATE"
    provisioning_model  = "STANDARD"
  }
  service_account {
    email  = "default"
    scopes = ["https://www.googleapis.com/auth/devstorage.read_only", "https://www.googleapis.com/auth/logging.write", "https://www.googleapis.com/auth/monitoring.write", "https://www.googleapis.com/auth/pubsub", "https://www.googleapis.com/auth/service.management.readonly", "https://www.googleapis.com/auth/servicecontrol", "https://www.googleapis.com/auth/trace.append"]
  }
  tags = ["load-balanced-backend"]
}

To create the managed instance group, use the google_compute_instance_group_manager resource.

lb/regional_external_http_load_balancer/main.tf 
resource "google_compute_instance_group_manager" "default" {
  name = "l7-xlb-backend-example"
  zone = "us-west1-a"
  named_port {
    name = "http"
    port = 80
  }
  version {
    instance_template = google_compute_instance_template.default.id
    name              = "primary"
  }
  base_instance_name = "vm"
  target_size        = 2
}

API

  1. Create the instance template with the instanceTemplates.insert method, replacing PROJECT_ID with your project ID.

    POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/global/instanceTemplates
{
 "name":"l7-xlb-backend-template",
 "properties": {
   "machineType":"e2-standard-2",
   "tags": {
     "items":[
       "load-balanced-backend"
     ]
   },
   "metadata": {
     "kind":"compute#metadata",
     "items":[
       {
         "key":"startup-script",
         "value":"#! /bin/bash\napt-get update\napt-get install apache2 -y\na2ensite default-ssl\na2enmod ssl\nvm_hostname=\"$(curl -H \"Metadata-Flavor:Google\" \\\nhttp://metadata.google.internal/computeMetadata/v1/instance/name)\"\necho \"Page served from: $vm_hostname\" | \\\ntee /var/www/html/index.html\nsystemctl restart apache2"
       }
     ]
   },
   "networkInterfaces":[
     {
       "network":"projects/PROJECT_ID/global/networks/lb-network",
       "subnetwork":"regions/us-west1/subnetworks/backend-subnet",
       "accessConfigs":[
         {
           "type":"ONE_TO_ONE_NAT"
         }
       ]
     }
   ],
   "disks": [
     {
       "index":0,
       "boot":true,
       "initializeParams": {
         "sourceImage":"projects/debian-cloud/global/images/family/debian-10"
       },
       "autoDelete":true
     }
   ]
 }
}

  2. Create a managed instance group in each zone with the instanceGroupManagers.insert method, replacing PROJECT_ID with your project ID.

    POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/zones/{zone}/instanceGroupManagers
{
 "name": "l7-xlb-backend-example",
 "zone": "projects/PROJECT_ID/zones/us-west1-a",
 "instanceTemplate": "projects/PROJECT_ID/global/instanceTemplates/l7-xlb-backend-template",
 "baseInstanceName": "l7-xlb-backend-example",
 "targetSize": 2
}

Add a named port to the instance group

For your instance group, define an HTTP service and map a port name to the relevant port. The backend service of the load balancer forwards traffic to the named port.

Console

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

    Go to Instance groups

  2. Click the name of your instance group (in this example l7-xlb-backend-example).

  3. On the instance group's Overview page, click Edit .

  4. Click Specify port name mapping.

  5. Click Add item.

  6. For the port name, enter http. For the port number, enter 80.

  7. Click Save.

gcloud

Use the gcloud compute instance-groups set-named-ports command.

gcloud compute instance-groups set-named-ports l7-xlb-backend-example \
    --named-ports http:80 \
    --zone us-west1-a

Terraform

The named_port attribute is included in the managed instance group sample.

Reserve the load balancer's IP address

Console

  1. In the Google Cloud console, go to the Reserve a static address page.

    Go to Reserve a static address

  2. Choose a Name for the new address.

  3. For Network Service Tier, select Standard.

  4. For IP version, select IPv4. IPv6 addresses can only be global and can only be used with global load balancers.

  5. For Type, select Regional.

  6. For Region, select us-west1.

  7. Leave the Attached to option set to None. After you create the load balancer, this IP address will be attached to the load balancer's forwarding rule.

  8. Click Reserve to reserve the IP address.

gcloud

  1. To reserve a static external IP address using gcloud compute, use the compute addresses create command.

    gcloud compute addresses create ADDRESS_NAME  \
   --region=us-west1 \
   --network-tier=STANDARD

    Replace the following:

    • ADDRESS_NAME: the name you want to call this address.
    • REGION: the region where you want to reserve this address. This region should be the same region as the load balancer. All regional IP addresses are IPv4.

  2. Use the compute addresses describe command to view the result:

    gcloud compute addresses describe ADDRESS_NAME

Terraform

To reserve the IP address, use the google_compute_address resource.

lb/regional_external_http_load_balancer/main.tf 
resource "google_compute_address" "default" {
  name         = "address-name"
  address_type = "EXTERNAL"
  network_tier = "STANDARD"
  region       = "us-west1"
}

To learn how to apply or remove a Terraform configuration, see Basic Terraform commands.

API

To create a regional IPv4 address, call the regional addresses.insert method:

POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/regions/REGION/addresses

Your request body should contain the following:

{
  "name": "ADDRESS_NAME"
  "networkTier": "STANDARD"
  "region": "us-west1"
}

Replace the following:

  • ADDRESS_NAME: the name for the address
  • REGION: the name of the region for this request
  • PROJECT_ID: the project ID for this request

Configure the load balancer

This example shows you how to create the following regional external Application Load Balancer resources:

  • HTTP health check
  • Backend service with a managed instance group as the backend
  • A URL map
    • Make sure to refer to a regional URL map if a region is defined for the target HTTP(S) proxy. A regional URL map routes requests to a regional backend service based on rules that you define for the host and path of an incoming URL. A regional URL map can be referenced by a regional target proxy rule in the same region only.
  • SSL certificate (for HTTPS)
  • Target proxy
  • Forwarding rule

Proxy availability

Sometimes Google Cloud regions don't have enough proxy capacity for a new load balancer. If this happens, the Google Cloud console provides a proxy availability warning message when you are creating your load balancer. To resolve this issue, you can do one of the following:

  • Select a different region for your load balancer. This can be a practical option if you have backends in another region.
  • Select a VPC network that already has an allocated proxy-only subnet.
  • Wait for the capacity issue to be resolved.

Console

  1. In the Google Cloud console, go to the Create a load balancer page.

    Go to Create a load balancer

  2. On the Application Load Balancer (HTTP/S) card, click Start configuration.

  3. For Internet facing or internal only, select From Internet to my VMs or serverless services. This setting means that the load balancer is an external Application Load Balancer.

  4. For Global or regional, select Regional HTTP(S) Load Balancer.

  5. Click Continue.

Create a regional external Application Load Balancer

  1. For the name of the load balancer, enter regional-l7-xlb.
  2. For Region, select us-west1.
  3. For Network, select lb-network.

Reserve a proxy-only subnet

For a regional external Application Load Balancer, reserve a proxy-only subnet:

  1. Click Reserve subnet.
  2. For Name, enter proxy-only-subnet.
  3. For IP address range, enter 10.129.0.0/23.
  4. Click Add.

Configure the frontend

For HTTP:

  1. Click Frontend configuration.
  2. Set Name to l7-xlb-forwarding-rule.
  3. Set Protocol to HTTP.
  4. Set Port to 80.
  5. Select the IP address that you created in Reserving the load balancer's IP address.
  6. Click Done.

For HTTPS:

If you are using HTTPS between the client and the load balancer, you need one or more SSL certificate resources to configure the proxy. For information about how to create SSL certificate resources, see SSL certificates. Google-managed certificates aren't currently supported with regional external Application Load Balancers.

  1. Click Frontend configuration.
  2. In the Name field, enter l7-xlb-forwarding-rule.
  3. In the Protocol field, select HTTPS (includes HTTP/2).
  4. Ensure that the Port is set to 443.
  5. Select the IP address that you created in Reserving the load balancer's IP address.
  6. In the Certificate list, do the following:
    1. If you already have a self-managed SSL certificate resource, select the primary SSL certificate.
    2. Click Create a new certificate.
      1. In the Name field, enter l7-xlb-cert.
      2. In the appropriate fields, upload your PEM-formatted files:
        • Public key certificate
        • Certificate chain
        • Private key
      3. Click Create.
  7. Optional: To add certificates in addition to the primary SSL certificate:
    1. Click Add certificate.
    2. If you already have a certificate, select it from the Certificates list.
    3. Optional: Click Create a new certificate and follow the instructions as specified in the previous step.
  8. Select an SSL policy from the SSL policy list. If you have not created any SSL policies, a default Google Cloud SSL policy is applied.
  9. Click Done.

Configure the backend service

  1. Click Backend configuration.
  2. From the Create or select backend services menu, select Create a backend service.
  3. Set the name of the backend service to l7-xlb-backend-service.
  4. For Protocol, select HTTP.
  5. For Named Port, enter http.
  6. Set Backend type to Instance group.
  7. In the New backend section:
    1. Set Instance group to l7-xlb-backend-example.
    2. Set Port numbers to 80.
    3. Set Balancing mode to Utilization.
    4. Click Done.
  8. In the Health check list, click Create a health check.
    1. Set Name to l7-xlb-basic-check.
    2. Set Protocol to HTTP.
    3. Set Port to 80.
    4. Click Save.
  9. Click Create.

Configure the routing rules

  1. Click Routing rules.
  2. For Mode, select Simple host and path rule.
  3. Ensure that the l7-xlb-backend-service is the only backend service for any unmatched host and any unmatched path.

Review the configuration

  1. Click Review and finalize.
  2. Review your load balancer configuration settings.
  3. Optional: Click Equivalent code to view the REST API request that will be used to create the load balancer.
  4. Click Create.

gcloud

  1. Define the HTTP health check with the gcloud compute health-checks create http command.

    gcloud compute health-checks create http l7-xlb-basic-check \
   --region=us-west1 \
   --request-path='/' \
   --use-serving-port

  2. Define the backend service with the gcloud compute backend-services create command.

    gcloud compute backend-services create l7-xlb-backend-service \
  --load-balancing-scheme=EXTERNAL_MANAGED \
  --protocol=HTTP \
  --port-name=http \
  --health-checks=l7-xlb-basic-check \
  --health-checks-region=us-west1 \
  --region=us-west1

  3. Add backends to the backend service with the gcloud compute backend-services add-backend command.

    gcloud compute backend-services add-backend l7-xlb-backend-service \
  --balancing-mode=UTILIZATION \
  --instance-group=l7-xlb-backend-example \
  --instance-group-zone=us-west1-a \
  --region=us-west1

  4. Create the URL map with the gcloud compute url-maps create command.

    gcloud compute url-maps create regional-l7-xlb-map \
  --default-service=l7-xlb-backend-service \
  --region=us-west1

  5. Create the target proxy.

    For HTTP:

    For an HTTP load balancer, create the target proxy with the gcloud compute target-http-proxies create command.

    gcloud compute target-http-proxies create l7-xlb-proxy \
  --url-map=regional-l7-xlb-map \
  --url-map-region=us-west1 \
  --region=us-west1

    For HTTPS:

    For information about how to create SSL certificate resources, see SSL certificates. Google-managed certificates aren't supported with regional external Application Load Balancers.

    1. Assign your filepaths to variable names.

      export LB_CERT=path to PEM-formatted file

      export LB_PRIVATE_KEY=path to PEM-formatted file

    2. Create a regional SSL certificate using the gcloud compute ssl-certificates create command.

      gcloud compute ssl-certificates create l7-xlb-cert \
 --certificate=$LB_CERT \
 --private-key=$LB_PRIVATE_KEY \
 --region=us-west1

    3. Use the regional SSL certificate to create a target proxy with the gcloud compute target-https-proxies create command.

      gcloud compute target-https-proxies create l7-xlb-proxy \
 --url-map=regional-l7-xlb-map \
 --region=us-west1 \
 --ssl-certificates=l7-xlb-cert

  6. Create the forwarding rule.

    For HTTP:

    Use the gcloud compute forwarding-rules create command with the correct flags.

    gcloud compute forwarding-rules create l7-xlb-forwarding-rule \
  --load-balancing-scheme=EXTERNAL_MANAGED \
  --network-tier=STANDARD \
  --network=lb-network \
  --address=ADDRESS_NAME \
  --ports=80 \
  --region=us-west1 \
  --target-http-proxy=l7-xlb-proxy \
  --target-http-proxy-region=us-west1

    For HTTPS:

    Create the forwarding rule with the gcloud compute forwarding-rules create command with the correct flags.

    gcloud compute forwarding-rules create l7-xlb-forwarding-rule \
  --load-balancing-scheme=EXTERNAL_MANAGED \
  --network-tier=STANDARD \
  --network=lb-network \
  --address=ADDRESS_NAME \
  --ports=443 \
  --region=us-west1 \
  --target-https-proxy=l7-xlb-proxy \
  --target-https-proxy-region=us-west1

Terraform

To create the health check, use the google_compute_region_health_check resource.

lb/regional_external_http_load_balancer/main.tf 
resource "google_compute_region_health_check" "default" {
  name               = "l7-xlb-basic-check"
  check_interval_sec = 5
  healthy_threshold  = 2
  http_health_check {
    port_specification = "USE_SERVING_PORT"
    proxy_header       = "NONE"
    request_path       = "/"
  }
  region              = "us-west1"
  timeout_sec         = 5
  unhealthy_threshold = 2
}

To create the backend service, use the google_compute_region_backend_service resource.

lb/regional_external_http_load_balancer/main.tf 
resource "google_compute_region_backend_service" "default" {
  name                  = "l7-xlb-backend-service"
  region                = "us-west1"
  load_balancing_scheme = "EXTERNAL_MANAGED"
  health_checks         = [google_compute_region_health_check.default.id]
  protocol              = "HTTP"
  session_affinity      = "NONE"
  timeout_sec           = 30
  backend {
    group           = google_compute_instance_group_manager.default.instance_group
    balancing_mode  = "UTILIZATION"
    capacity_scaler = 1.0
  }
}

To create the URL map, use the google_compute_region_url_map resource.

lb/regional_external_http_load_balancer/main.tf 
resource "google_compute_region_url_map" "default" {
  name            = "regional-l7-xlb-map"
  region          = "us-west1"
  default_service = google_compute_region_backend_service.default.id
}

To create the target HTTP proxy, use the google_compute_region_target_http_proxy resource.

lb/regional_external_http_load_balancer/main.tf 
resource "google_compute_region_target_http_proxy" "default" {
  name    = "l7-xlb-proxy"
  region  = "us-west1"
  url_map = google_compute_region_url_map.default.id
}

To create the forwarding rule, use the google_compute_forwarding_rule resource.

lb/regional_external_http_load_balancer/main.tf 
resource "google_compute_forwarding_rule" "default" {
  name       = "l7-xlb-forwarding-rule"
  provider   = google-beta
  depends_on = [google_compute_subnetwork.proxy_only]
  region     = "us-west1"

  ip_protocol           = "TCP"
  load_balancing_scheme = "EXTERNAL_MANAGED"
  port_range            = "80"
  target                = google_compute_region_target_http_proxy.default.id
  network               = google_compute_network.default.id
  ip_address            = google_compute_address.default.id
  network_tier          = "STANDARD"
}

To learn how to apply or remove a Terraform configuration, see Basic Terraform commands.

API

Create the health check by making a POST request to the regionHealthChecks.insert method, replacing PROJECT_ID with your project ID.

POST https://compute.googleapis.com/compute/v1/projects/<var>PROJECT_ID</var>/regions/{region}/healthChecks
{
  "name": "l7-xlb-basic-check",
  "type": "HTTP",
  "httpHealthCheck": {
    "portSpecification": "USE_SERVING_PORT"
  }
}

Create the regional backend service by making a POST request to the regionBackendServices.insert method, replacing PROJECT_ID with your project ID.

POST https://compute.googleapis.com/compute/v1/projects/<var>PROJECT_ID</var>/regions/us-west1/backendServices
{
  "name": "l7-xlb-backend-service",
  "backends": [
    {
      "group": "projects/<var>PROJECT_ID</var>/zones/us-west1-a/instanceGroups/l7-xlb-backend-example",
      "balancingMode": "UTILIZATION"
    }
  ],
  "healthChecks": [
    "projects/<var>PROJECT_ID</var>/regions/us-west1/healthChecks/l7-xlb-basic-check"
  ],
  "loadBalancingScheme": "EXTERNAL_MANAGED"
}

Create the URL map by making a POST request to the regionUrlMaps.insert method, replacing PROJECT_ID with your project ID.

POST https://compute.googleapis.com/compute/v1/projects/<var>PROJECT_ID</var>/regions/us-west1/urlMaps
{
  "name": "regional-l7-xlb-map",
  "defaultService": "projects/<var>PROJECT_ID</var>/regions/us-west1/backendServices/l7-xlb-backend-service"
}

Create the target HTTP proxy by making a POST request to the regionTargetHttpProxies.insert method, replacing PROJECT_ID with your project ID.

POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/regions/us-west1/targetHttpProxy
{
  "name": "l7-xlb-proxy",
  "urlMap": "projects/PROJECT_ID/global/urlMaps/regional-l7-xlb-map",
  "region": "us-west1"
}

Create the forwarding rule by making a POST request to the forwardingRules.insert method, replacing PROJECT_ID with your project ID.

POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/regions/us-west1/forwardingRules
{
  "name": "l7-xlb-forwarding-rule",
  "IPAddress": "10.1.2.99",
  "IPProtocol": "TCP",
  "portRange": "80-80",
  "target": "projects/PROJECT_ID/regions/us-west1/targetHttpProxies/l7-xlb-proxy",
  "loadBalancingScheme": "EXTERNAL_MANAGED",
  "network": "projects/PROJECT_ID/global/networks/lb-network",
  "networkTier": "STANDARD",
}

Connect your domain to your load balancer

After the load balancer is created, note the IP address that is associated with the load balancer—for example, 30.90.80.100. To point your domain to your load balancer, create an A record by using your domain registration service. If you added multiple domains to your SSL certificate, you must add an A record for each one, all pointing to the load balancer's IP address. For example, to create A records for www.example.com and example.com, use the following:

NAME                  TYPE     DATA
www                   A        30.90.80.100
@                     A        30.90.80.100

If you are using Google Domains, for more information, see Google Domains Help.

Test the load balancer

Now that the load balancing service is running, you can send traffic to the forwarding rule and watch the traffic be dispersed to different instances.

Console

  1. In the Google Cloud console, go to the Load balancing page.

    Go to Load balancing

  2. Select the load balancer that you just created.
  3. In the Backend section, confirm that the VMs are healthy. The Healthy column should be populated, indicating that both VMs are healthy (2/2). If you see otherwise, first try reloading the page. It can take a few moments for the Google Cloud console to indicate that the VMs are healthy. If the backends do not appear healthy after a few minutes, review the firewall configuration and the network tag assigned to your backend VMs.
  4. After the Google Cloud console shows that the backend instances are healthy, you can test your load balancer using a web browser by going to https://IP_ADDRESS (or http://IP_ADDRESS). Replace IP_ADDRESS with the load balancer's IP address.
  5. If you used a self-signed certificate for testing HTTPS, your browser displays a warning. You must explicitly instruct your browser to accept a self-signed certificate.
  6. Your browser should render a page with content showing the name of the instance that served the page, along with its zone (for example, Page served from: lb-backend-example-xxxx). If your browser doesn't render this page, review the configuration settings in this guide.

gcloud

Note the IPv4 address that was reserved:

gcloud beta compute addresses describe ADDRESS_NAME \
    --format="get(address)" \
    --region="us-west1"

You can test your load balancer using a web browser by going to https://IP_ADDRESS (or http://IP_ADDRESS). Replace IP_ADDRESS with the load balancer's IP address.

If you used a self-signed certificate for testing HTTPS, your browser displays a warning. You must explicitly instruct your browser to accept a self-signed certificate.

Your browser should render a page with minimal information about the backend instance. If your browser doesn't render this page, review the configuration settings in this guide.

Additional configuration options

This section expands on the configuration example to provide alternative and additional configuration options. All of the tasks are optional. You can perform them in any order.

Enable session affinity

These procedures show you how to update a backend service for the example regional external Application Load Balancer so that the backend service uses generated cookie affinity, header field affinity, or HTTP cookie affinity.

When generated cookie affinity is enabled, the load balancer issues a cookie on the first request. For each subsequent request with the same cookie, the load balancer directs the request to the same backend VM or endpoint. For regional external Application Load Balancers, the cookie is named GCILB.

When header field affinity is enabled, the load balancer routes requests to backend VMs or endpoints in a NEG based on the value of the HTTP header named in the --custom-request-header flag. Header field affinity is only valid if the load balancing locality policy is either RING_HASH or MAGLEV and the backend service's consistent hash specifies the name of the HTTP header.

When HTTP cookie affinity is enabled, the load balancer routes requests to backend VMs or endpoints in a NEG, based on an HTTP cookie named in the HTTP_COOKIE flag with the optional --affinity-cookie-ttl flag. If the client does not provide the cookie in its HTTP request, the proxy generates the cookie and returns it to the client in a Set-Cookie header. HTTP cookie affinity is only valid if the load balancing locality policy is either RING_HASH or MAGLEV and the backend service's consistent hash specifies the HTTP cookie.

Console

To enable or change session affinity for a backend service:

  1. In the Google Cloud console, go to the Load balancing page.

    Go to Load balancing

  2. Select the load balancer that you just created.

  3. Click Backends.

  4. Click l7-xlb-backend-service (the name of the backend service you created for this example) and click Edit.

  5. On the Backend service details page, click Advanced configuration.

  6. For Session affinity, select the type of session affinity you want from the menu.

  7. Click Update.

gcloud

Use the following gcloud commands to update the l7-xlb-backend-service backend service to different types of session affinity:

gcloud compute backend-services update l7-xlb-backend-service \
    --session-affinity=[GENERATED_COOKIE | HEADER_FIELD | HTTP_COOKIE | CLIENT_IP]
    --region=us-west1

API

To set session affinity, make a PATCH request to the regionBackendServices/patch method.

PATCH https://compute.googleapis.com/compute/v1/projects/[PROJECT_ID]/regions/us-west1/regionBackendServices/l7-xlb-backend-service
{
  "sessionAffinity": ["GENERATED_COOKIE" | "HEADER_FIELD" | "HTTP_COOKIE" | "CLIENT_IP" ]
}

What's next