Set up a classic Application Load Balancer with hybrid connectivity

This page illustrates how to deploy the classic Application Load Balancer to load balance traffic to network endpoints that are on-premises or in other public clouds and are reachable by using hybrid connectivity.

Note: For regional external Application Load Balancer instructions, see Set up a regional external Application Load Balancer with hybrid connectivity. For global external Application Load Balancer instructions, see Set up a global external Application Load Balancer with hybrid connectivity.

After you complete these tasks, you can optionally explore enabling additional services (such as Cloud CDN and Google Cloud Armor) and advanced traffic management features.

If you haven't already done so, review the Hybrid connectivity NEGs overview to understand the network requirements to set up hybrid load balancing.

Setup overview

The example on this page sets up the following sample deployment:

External Application Load Balancer example for hybrid connectivity (click to enlarge).

You must configure hybrid connectivity before you attempt to set up a hybrid load balancing deployment. This document does not include the hybrid connectivity setup.

Depending on your choice of hybrid connectivity product (either Cloud VPN or Cloud Interconnect (Dedicated or Partner)), use the relevant product documentation to configure this.

Permissions

To set up hybrid load balancing, you must have the following permissions:

• On Google Cloud

  • Permissions to establish hybrid connectivity between Google Cloud and your on-premises environment or other cloud environments. For the list of permissions needed, see the relevant Network Connectivity product documentation.
  • Permissions to create a hybrid connectivity NEG and the load balancer. The Compute Load Balancer Admin role (roles/compute.loadBalancerAdmin) contains the permissions required to perform the tasks described in this guide.

• On your on-premises environment or other non-Google Cloud cloud environment

  • Permissions to configure network endpoints that allow services on your on-premises environment or other cloud environments to be reachable from Google Cloud by using an IP:Port combination. For more information, contact your environment's network administrator.
  • Permissions to create firewall rules on your on-premises environment or other cloud environments to allow Google's health check probes to reach the endpoints.

Additionally, to complete the instructions on this page, you need to create a hybrid connectivity NEG, a load balancer, and zonal NEGs (and their endpoints) to serve as Google Cloud-based backends for the load balancer.

You should be either a project Owner or Editor, or you should have the following Compute Engine IAM roles.

Task	Required role
Create networks, subnets, and load balancer components	Compute Network Admin (roles/compute.networkAdmin)
Add and remove firewall rules	Compute Security Admin (roles/compute.securityAdmin)
Create instances	Compute Instance Admin (roles/compute.instanceAdmin)

Establish hybrid connectivity

Your Google Cloud and on-premises environment or other cloud environments must be connected through hybrid connectivity by using either Cloud Interconnect VLAN attachments or Cloud VPN tunnels with Cloud Router. We recommend that you use a high availability connection.

A Cloud Router enabled with global dynamic routing learns about the specific endpoint through Border Gateway Protocol (BGP) and programs it into your Google Cloud VPC network. Regional dynamic routing is not supported. Static routes are also not supported.

The VPC network that you use to configure either Cloud Interconnect or Cloud VPN is the same network that you use to configure the hybrid load balancing deployment. Ensure that your VPC network's subnet CIDR ranges do not conflict with your remote CIDR ranges. When IP addresses overlap, subnet routes are prioritized over remote connectivity.

For instructions, see the following documentation:

• Cloud VPN
• Cloud Interconnect

Important: Don't proceed with the instructions on this page until you set up hybrid connectivity between your environments.

Set up your environment that is outside Google Cloud

Perform the following steps to set up your on-premises environment or other cloud environment for hybrid load balancing:

• Configure network endpoints to expose on-premises services to Google Cloud (IP:Port).
• Configure firewall rules on your on-premises environment or other cloud environment.
• Configure Cloud Router to advertise certain required routes to your private environment.

Set up network endpoints

After you set up hybrid connectivity, you configure one or more network endpoints within your on-premises environment or other cloud environments that are reachable through Cloud Interconnect or Cloud VPN by using an IP:port combination. This IP:port combination is configured as one or more endpoints for the hybrid connectivity NEG that is created in Google Cloud later on in this process.

If there are multiple paths to the IP endpoint, routing follows the behavior described in the Cloud Router overview.

Set up firewall rules

The following firewall rules must be created on your on-premises environment or other cloud environment:

• Create an ingress allow firewall rule to allow traffic from Google's health-checking probes to your endpoints. The source IP address ranges to be allowed are 35.191.0.0/16 and 130.211.0.0/22. For more information, see Probe IP ranges and firewall rules.

Advertise routes

Configure Cloud Router to advertise the following custom IP ranges to your on-premises environment or other cloud environment:

• The ranges used by Google's health check probes: 35.191.0.0/16 and 130.211.0.0/22.

Set up the Google Cloud environment

For the following steps, make sure you use the same VPC network (called NETWORK in this procedure) that was used to configure hybrid connectivity between the environments.

Create the subnet for the backends

This subnet is used to create the load balancer's zonal NEG backends, the frontend, and the internal IP address.

Create this subnet in the NETWORK network that was used to configure hybrid connectivity between the environments.

Console

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

   Go to VPC networks

2. Go to the network that was used to configure hybrid connectivity between the environments.

3. In the Subnets section:

   1. Set the Subnet creation mode to Custom.
   2. In the New subnet section, enter the following information:
      • Name: LB_SUBNET_NAME
      • Region: REGION
      • IP address range: LB_SUBNET_RANGE
   3. Click Done.

4. Click Create.

gcloud

Create a subnet in the NETWORK network that was used to configure hybrid connectivity between the environments.

gcloud compute networks subnets create LB_SUBNET_NAME \
    --network=NETWORK \
    --range=LB_SUBNET_RANGE \
    --region=REGION

Create firewall rule

In this example, you create the following firewall rule:

• fw-allow-health-check: An ingress rule, applicable to the Google Cloud instances being load balanced, that allows traffic from the load balancer and Google Cloud health checking systems (130.211.0.0/22 and 35.191.0.0/16). This example uses the target tag allow-health-check to identify the backend VMs to which it should apply.

Console

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

   Go to Firewall policies

2. Click Create firewall rule:

   1. Enter a Name of fw-allow-health-check.
   2. In the Network section, select NETWORK.
   3. Under Targets, select Specified target tags.
   4. Populate the Target tags field with allow-health-check.
   5. Set Source filter to IPv4 ranges.
   6. Set Source IPv4 ranges to 130.211.0.0/22 and 35.191.0.0/16.
   7. Under Protocols and ports, select Specified protocols and ports.
   8. Select the checkbox next to TCP and type 80 for the port numbers.

3. Click Create.

gcloud

1. Create the fw-allow-health-check-and-proxy rule to allow the load balancer and Google Cloud health checks to communicate with backend instances on TCP port 80.

   Replace NETWORK with the name of the VPC network used to configure hybrid connectivity.

   gcloud compute firewall-rules create fw-allow-health-check \
       --network=NETWORK \
       --action=allow \
       --direction=ingress \
       --target-tags=allow-health-check \
       --source-ranges=130.211.0.0/22,35.191.0.0/16 \
       --rules=tcp:80
   

Set up the zonal NEG

For Google Cloud-based backends, we recommend you configure multiple zonal NEGs in the same region where you configured hybrid connectivity.

For this example, we set up a zonal NEG (with GCE_VM_IP_PORT type endpoints) in the REGION region. First create the VMs in the GCP_NEG_ZONE zone. Then create a zonal NEG in the same GCP_NEG_ZONE and add the VMs' network endpoints to the NEG.

Create VMs

Console

1. Go to the VM instances page in the Google Cloud console.
   Go to VM instances

2. Click Create instance.

3. Set the Name to vm-a1.

4. For the Region, choose REGION.

5. For the Zone, choose GCP_NEG_ZONE.

6. In the Boot disk section, ensure that Debian GNU/Linux 12 (bookworm) is selected for the boot disk options. Click Choose to change the image if necessary.

7. Click Advanced options and make the following changes:

   • Click Networking and add the following Network tags: allow-health-check.
   • Click Edit under Network interfaces and make the following changes then click Done:
     • Network: NETWORK
     • Subnet: LB_SUBNET_NAME
     • IP stack type: IPv4 and IPv6 (dual-stack)

   • Click Management. In the Startup script field, copy and paste the following script contents. The script contents are identical for all four VMs:

     #! /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
     

8. Click Create.

9. Repeat the following steps to create a second VM, using the following name and zone combination:

   • Name: vm-a2, zone: GCP_NEG_ZONE

gcloud

Create the VMs by running the following command two times, using these combinations for the name of the VM and its zone. The script contents are identical for both VMs.

• VM_NAME of vm-a1 and any GCP_NEG_ZONE zone of your choice

• VM_NAME of vm-a2 and the same GCP_NEG_ZONE zone

  To support IPv4 traffic, run the following command:

  gcloud compute instances create VM_NAME \
      --zone=GCP_NEG_ZONE \
      --image-family=debian-10 \
      --image-project=debian-cloud \
      --tags=allow-health-check \
      --ipv6-network-tier=PREMIUM
      --stack-type=IPV4_ONLY \
      --subnet=LB_SUBNET_NAME \
      --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'
  

Create the zonal NEG

Console

To create a zonal network endpoint group:

1. Go to the Network Endpoint Groups page in the Google Cloud console.
   Go to the Network Endpoint Groups page
   
2. Click Create network endpoint group.
3. Enter a Name for the zonal NEG. Referred to as GCP_NEG_NAME in this procedure.
4. Select the Network endpoint group type: Network endpoint group (Zonal).
5. Select the Network: NETWORK
6. Select the Subnet: LB_SUBNET_NAME
7. Select the Zone: GCP_NEG_ZONE
8. Enter the Default port: 80.
9. Click Create.

Add endpoints to the zonal NEG:

1. Go to the Network Endpoint Groups page in the Google Cloud console.
   Go to the Network endpoint groups
   
2. Click the Name of the network endpoint group created in the previous step (GCP_NEG_NAME). You see the Network endpoint group details page.
3. In the Network endpoints in this group section, click Add network endpoint. You see the Add network endpoint page.
4. Select a VM instance to add its internal IP addresses as network endpoints. In the Network interface section, the name, zone, and subnet of the VM is displayed.
5. In the IPv4 address field, enter the IPv4 address of the new network endpoint.
6. Select the Port type.
   1. If you select Default, the endpoint uses the default port 80 for all endpoints in the network endpoint group. This is sufficient for our example because the Apache server is serving requests at port 80.
   2. If you select Custom, enter the Port number for the endpoint to use.
7. To add more endpoints, click Add network endpoint and repeat the previous steps.
8. After you add all the endpoints, click Create.

gcloud

1. Create a zonal NEG (with GCE_VM_IP_PORT endpoints) using the gcloud compute network-endpoint-groups create command:

   gcloud compute network-endpoint-groups create GCP_NEG_NAME \
       --network-endpoint-type=GCE_VM_IP_PORT \
       --zone=GCP_NEG_ZONE \
       --network=NETWORK \
       --subnet=LB_SUBNET_NAME
   

   You can either specify a --default-port while creating the NEG, or specify a port number for each endpoint as shown in the next step.

2. Add single-stack endpoints to GCP_NEG_NAME.

   gcloud compute network-endpoint-groups update GCP_NEG_NAME \
       --zone=GCP_NEG_ZONE \
       --add-endpoint='instance=vm-a1,port=80' \
       --add-endpoint='instance=vm-a2,port=80'
   

Set up the hybrid connectivity NEG

When creating the NEG, use a ZONE that minimizes the geographic distance between Google Cloud and your on-premises or other cloud environment. For example, if you are hosting a service in an on-premises environment in Frankfurt, Germany, you can specify the europe-west3-a Google Cloud zone when you create the NEG.

Moreover, if you're using Cloud Interconnect, the ZONE used to create the NEG should be in the same region where the hybrid connectivity Cloud Interconnect VLAN attachment was configured.

For the available regions and zones, see the Compute Engine documentation: Available regions and zones.

Console

To create a hybrid connectivity network endpoint group:

1. Go to the Network Endpoint Groups page in the Google Cloud console.
   Go to Network endpoint groups
   
2. Click Create network endpoint group.
3. Enter a Name for the hybrid NEG. Referred to as ON_PREM_NEG_NAME in this procedure.
4. Select the Network endpoint group type: Hybrid connectivity network endpoint group (Zonal).
5. Select the Network: NETWORK
6. Select the Subnet: LB_SUBNET_NAME
7. Select the Zone: ON_PREM_NEG_ZONE
8. Enter the Default port.
9. Click Create

Add endpoints to the hybrid connectivity NEG:

1. Go to the Network Endpoint Groups page in the Google Cloud console.
   Go to the Network Endpoint Groups page
   
2. Click the Name of the network endpoint group created in the previous step (ON_PREM_NEG_NAME). You see the Network endpoint group detail page.
3. In the Network endpoints in this group section, click Add network endpoint. You see the Add network endpoint page.
4. Enter the IP address of the new network endpoint.
5. Select the Port type.
   1. If you select Default, the endpoint uses the default port for all endpoints in the network endpoint group.
   2. If you select Custom, you can enter a different Port number for the endpoint to use.
6. To add more endpoints, click Add network endpoint and repeat the previous steps.
7. After you add all the non-Google Cloud endpoints, click Create.

gcloud

1. Create a hybrid connectivity NEG using the gcloud compute network-endpoint-groups create command.

   gcloud compute network-endpoint-groups create ON_PREM_NEG_NAME \
       --network-endpoint-type=NON_GCP_PRIVATE_IP_PORT \
       --zone=ON_PREM_NEG_ZONE \
       --network=NETWORK
   

2. Add the endpoint to on-prem-neg:

   gcloud compute network-endpoint-groups update ON_PREM_NEG_NAME \
       --zone=ON_PREM_NEG_ZONE \
       --add-endpoint="ip=ON_PREM_IP_ADDRESS_1,port=PORT_1" \
       --add-endpoint="ip=ON_PREM_IP_ADDRESS_2,port=PORT_2"
   

You can use this command to add the network endpoints you previously configured on-premises or in your cloud environment. Repeat --add-endpoint as many times as needed.

You can repeat these steps to create multiple hybrid NEGs if needed.

Configure the load balancer

Console

Note: You cannot use the Google Cloud console to create a load balancer that has mixed zonal and hybrid connectivity NEGs backends in a single backend service. Use either gcloud or the REST API instead.

gcloud

1. Create a global static external IP address to which external clients send traffic.

     gcloud compute addresses create LB_IP_ADDRESS_NAME \
         --global
     

2. Create a health check for the backends.

     gcloud compute health-checks create http HTTP_HEALTH_CHECK_NAME \
         --use-serving-port
     

3. Create a backend service. You add both the zonal NEG and the hybrid connectivity NEG as backends to this backend service.

  gcloud compute backend-services create BACKEND_SERVICE \
      --health-checks=HTTP_HEALTH_CHECK_NAME \
      --global
  

4. Add the zonal NEG as a backend to the backend service:

     gcloud compute backend-services add-backend BACKEND_SERVICE \
         --global \
         --balancing-mode=RATE \
         --max-rate-per-endpoint=MAX_REQUEST_RATE_PER_ENDPOINT \
         --network-endpoint-group=GCP_NEG_NAME \
         --network-endpoint-group-zone=GCP_NEG_ZONE
      

   For details about configuring the balancing mode, see the gcloud CLI documentation for the --max-rate-per-endpoint parameter.
5. Add the hybrid NEG as a backend to the backend service:

     gcloud compute backend-services add-backend BACKEND_SERVICE \
         --global \
         --balancing-mode=RATE \
         --max-rate-per-endpoint=MAX_REQUEST_RATE_PER_ENDPOINT \
         --network-endpoint-group=ON_PREM_NEG_NAME \
         --network-endpoint-group-zone=ON_PREM_NEG_ZONE
     

6. Create a URL map to route incoming requests to the backend service.

     gcloud compute url-maps create URL_MAP_NAME \
         --default-service BACKEND_SERVICE
     

7. Perform this step only if you want to create an HTTPS load balancer. This is not required for HTTP load balancers.
   To create an HTTPS load balancer, you must have an SSL certificate resource to use in the HTTPS target proxy. You can create an SSL certificate resource using either a Google-managed SSL certificate or a self-managed SSL certificate. Using Google-managed certificates is recommended because Google Cloud obtains, manages, and renews these certificates automatically.
   
   To create a Google-managed certificate, you must have a domain. If you don't have a domain, you can use a self-signed SSL certificate for testing.
   
   To create a Google-managed SSL certificate resource:

   gcloud compute ssl-certificates create SSL_CERTIFICATE_NAME \
       --domains DOMAIN
   

   To create a self-managed SSL certificate resource:

   gcloud compute ssl-certificates create SSL_CERTIFICATE_NAME \
       --certificate CRT_FILE_PATH \
       --private-key KEY_FILE_PATH
   

8. Create a target HTTP(S) proxy to route requests to your URL map.
   
   For an HTTP load balancer, create an HTTP target proxy:

   gcloud compute target-http-proxies create TARGET_HTTP_PROXY_NAME \
       --url-map=URL_MAP_NAME
   

   For an HTTPS load balancer, create an HTTPS target proxy. The proxy is the portion of the load balancer that holds the SSL certificate for HTTPS Load Balancing, so you also load your certificate in this step.

   gcloud compute target-https-proxies create TARGET_HTTPS_PROXY_NAME \
       --ssl-certificates=SSL_CERTIFICATE_NAME \
       --url-map=URL_MAP_NAME
   

9. Create a forwarding rule to route incoming requests to the proxy.
   
   For an HTTP load balancer:

   gcloud compute forwarding-rules create HTTP_FORWARDING_RULE_NAME \
       --address=LB_IP_ADDRESS_NAME \
       --target-http-proxy=TARGET_HTTP_PROXY_NAME \
       --global \
       --ports=80
   

   For an HTTPS load balancer:

   gcloud compute forwarding-rules create HTTPS_FORWARDING_RULE_NAME \
       --address=LB_IP_ADDRESS_NAME \
       --target-https-proxy=TARGET_HTTPS_PROXY_NAME \
       --global \
       --ports=443
   

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 use Cloud DNS as your DNS provider, see Add, modify, and delete records.

Testing the load balancer

Note: It might take a few minutes for the load balancer configuration to propagate globally after you first deploy it.

Now that you have configured your load balancer, you can start sending traffic to the load balancer's IP address.

1. Go to the Load balancing page in the Google Cloud console.
   Go to the Load balancing page

2. Click on the load balancer you just created.

3. Note the IP Address of the load balancer.

4. Send traffic to the load balancer.

   • If you created an HTTP load balancer, you can test your load balancer using a web browser by going to http://IP_ADDRESS. Replace IP_ADDRESS with the load balancer's IP address. You should be directed to the service you have exposed through the endpoint.

   • If you created an HTTPS load balancer, you can test your load balancer by using curl as follows. Replace IP_ADDRESS with the load balancer's IP address. You should be directed to the service you have exposed through the endpoint.

     curl -k https://IP_ADDRESS
     

     If that does not work and you are using a Google-managed certificate, confirm that your certificate resource's status is ACTIVE. For more information, see Google-managed SSL certificate resource status. Then test the domain pointing to the load balancer's IP address. For example:

     curl -s https://test.example.com
     

5. Testing the non-Google Cloud endpoints depends on the service you have exposed through the hybrid NEG endpoint.

What's next

• Clean up the load balancer setup.