Set up a classic proxy Network Load Balancer (SSL proxy) with VM instance group backends

This document provides instructions for setting up a classic proxy Network Load Balancer with a target SSL proxy and VM instance group backends. Before you start, read External proxy Network Load Balancer overview for information on how these load balancers work.

Setup overview

This example demonstrates how to set up an external proxy Network Load Balancer for a service that exists in two regions: Region A and Region B. You will configure the following:

1. Four instances spread across two regions
2. Instance groups for holding the instances
3. Backend components, which include the following:
   • Health check - used to monitor instance health
   • Backend service - monitors instance groups and prevents them from exceeding configured usage
   • Backends - hold the instance groups
4. Frontend components, which include the following:
   • An SSL certificate resource. You can use either a self-managed certificate, where you supply your own SSL certificate, or a Google-managed certificate, where Google issues a certificate that is valid for all of your domains. For more information, see Types of SSL certificates.
   • The SSL proxy itself with its SSL certificate
   • An external static IPv4 address and a forwarding rule that sends user traffic to the proxy
   • An external static IPv6 address and a forwarding rule that sends user traffic to the proxy
5. A firewall rule that allows traffic from the load balancer and health checker to the instances.
6. Optionally, an SSL policy to control the features of SSL that your SSL proxy load balancer negotiates with clients.

After that, you'll test your configuration.

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	Compute Instance Admin

For more information, see the following guides:

• Access control
• IAM Conditions

Configure the network and subnets

To create the example network and subnet, follow these steps.

Console

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

   Go to VPC networks

2. Click Create VPC network.

3. Enter a Name for the network.

4. Choose Custom for the Subnet creation mode.

5. In the New subnet section, specify the following configuration parameters for a subnet:

   1. In the Name field, provide a name for the subnet.
   2. In the Region field, enter a region name.
   3. For IP stack type, select IPv4 (single-stack).
   4. In the IP address range field, enter an IP address range. This is the primary IPv4 range for the subnet.

6. Click Done.

7. To add a subnet in a different region, click Add subnet and repeat the previous steps.

8. Click Create.

gcloud

gcloud compute networks subnets update SUBNET \
    --network=NETWORK \
    --stack-type=IPV4_ONLY \
    --range=10.1.2.0/24 \
    --region=REGION_A

Replace the following:

• NETWORK: a name for the VPC network

• SUBNET: a name for the subnet

• REGION_A: the name of the region

Configure instances and instance groups

This section shows how to create instances and instance groups, then add the instances to the instance groups. A production system would normally use managed instance groups based on instance templates, but this setup is quicker for initial testing.

Create instances

Create these instances with the tag ssl-lb, which the firewall rule will use later.

Console

Create instances

1. In the Google Cloud console, go to the VM instances page.

   Go to VM instances

2. Click Create instance.

3. Set Name to vm-a1.

4. Set the Zone to ZONE_A.

5. Click Advanced options.

6. Click Networking and configure the following field:

   • In the Network tags field, enter ssl-lb and allow-health-check-ipv6.

7. In the Network interfaces section, click Edit and make the following changes:

   • Select the network.

   • Select a subnet.

   • Click Done.

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

   sudo apt-get update
   sudo apt-get install apache2 -y
   sudo a2ensite default-ssl
   sudo a2enmod ssl
   sudo service apache2 restart
   echo '<!doctype html><html><body><h1>vm-a1</h1></body></html>' | sudo tee /var/www/html/index.html

9. Leave the default values for rest of the fields.

10. Click Create.

11. Create vm-a2 with the same settings, except with Startup script set to the following:

    sudo apt-get update
    sudo apt-get install apache2 -y
    sudo a2ensite default-ssl
    sudo a2enmod ssl
    sudo service apache2 restart
    echo '<!doctype html><html><body><h1>vm-a2</h1></body></html>' | sudo tee /var/www/html/index.html

12. Create vm-b1 with the same settings, except with Zone set to ZONE_B and Startup script set to the following:

    sudo apt-get update
    sudo apt-get install apache2 -y
    sudo a2ensite default-ssl
    sudo a2enmod ssl
    sudo service apache2 restart
    echo '<!doctype html><html><body><h1>vm-b1</h1></body></html>' | sudo tee /var/www/html/index.html

13. Create vm-b2 with the same settings, except with Zone set to ZONE_B and Startup script set to the following:

    sudo apt-get update
    sudo apt-get install apache2 -y
    sudo a2ensite default-ssl
    sudo a2enmod ssl
    sudo service apache2 restart
    echo '<!doctype html><html><body><h1>vm-b2</h1></body></html>' | sudo tee /var/www/html/index.html

gcloud

1. Create vm-a1 in zone ZONE_A.

   gcloud compute instances create vm-a1 \
      --image-family debian-12 \
      --image-project debian-cloud \
      --tags ssl-lb \
      --zone ZONE_A \
      --metadata startup-script="#! /bin/bash
        sudo apt-get update
        sudo apt-get install apache2 -y
        sudo a2ensite default-ssl
        sudo a2enmod ssl
        sudo service apache2 restart
        echo '<!doctype html><html><body><h1>vm-a1</h1></body></html>' | sudo tee /var/www/html/index.html
        EOF"
   

2. Create vm-a2 in zone ZONE_A.

   gcloud compute instances create vm-a2 \
     --image-family=debian-12 \
     --image-project=debian-cloud \
     --tags=ssl-lb \
     --zone=ZONE_A \
     --metadata=startup-script="#! /bin/bash
       sudo apt-get update
       sudo apt-get install apache2 -y
       sudo a2ensite default-ssl
       sudo a2enmod ssl
       sudo service apache2 restart
       echo '<!doctype html><html><body><h1>vm-a2</h1></body></html>' | sudo tee /var/www/html/index.html
        EOF"
   

3. Create vm-b1 in zone ZONE_B.

   gcloud compute instances create vm-b1 \
     --image-family=debian-12 \
     --image-project=debian-cloud \
     --tags=ssl-lb \
     --zone=ZONE_B \
     --metadata=startup-script="#! /bin/bash
       sudo apt-get update
       sudo apt-get install apache2 -y
       sudo a2ensite default-ssl
       sudo a2enmod ssl
       sudo service apache2 restart
       echo '<!doctype html><html><body><h1>vm-b1</h1></body></html>' | sudo tee /var/www/html/index.html
       EOF"
   

4. Create vm-b2 in zone ZONE_B.

   gcloud compute instances create vm-b2 \
     --image-family=debian-12 \
     --image-project=debian-cloud \
     --tags=ssl-lb \
     --zone=ZONE_B \
     --metadata=startup-script="#! /bin/bash
       sudo apt-get update
       sudo apt-get install apache2 -y
       sudo a2ensite default-ssl
       sudo a2enmod ssl
       sudo service apache2 restart
       echo '<!doctype html><html><body><h1>vm-b2</h1></body></html>' | sudo tee /var/www/html/index.html
       EOF"
   

Create an instance group for each zone and add instances

Console

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

   Go to Instance groups

2. Click Create instance group.

3. Set the Name to instance-group-a.

4. Set the Zone to ZONE_A.

5. Under Port mapping, click Add port. A load balancer sends traffic to an instance group through a named port. Create a named port to map the incoming traffic to a specific port number.

   1. Enter a Port name of ssl-lb and Port numbers of 443.

6. Under Instance definition, click Select existing instances.

7. From VM instances select vm-a1 and vm-a2.

8. Leave other settings as they are.

9. Click Create.

10. Repeat steps, but set the following:

    • Name: instance-group-b
    • Zone: ZONE_B
    • Port name of ssl-lb and Port numbers of 443
    • Instances: vm-b1 and vm-b2.

11. Confirm that you now have two instance groups, each with two instances.

gcloud

1. Create the instance-group-a instance group.

   gcloud compute instance-groups unmanaged create instance-group-a --zone ZONE_A
   

2. Set a named port for the instance group.

   gcloud compute instance-groups set-named-ports instance-group-a \
       --named-ports=ssl-lb:443 \
       --zone=ZONE_A
   

3. Add vm-a1 and vm-a2 to instance-group-a

   gcloud compute instance-groups unmanaged add-instances instance-group-a \
       --instances=vm-a1,vm-a2 \
       --zone=ZONE_A
   

4. Create the instance-group-b instance group.

   gcloud compute instance-groups unmanaged create instance-group-b --zone ZONE_B
   

5. Set a named port for the instance group.

   gcloud compute instance-groups set-named-ports instance-group-b \
       --named-ports=ssl-lb:443 \
       --zone=ZONE_B
   

6. Add vm-b1 and vm-b2 to instance-group-b

   gcloud compute instance-groups unmanaged add-instances instance-group-b \
       --instances=vm-b1,vm-b2 \
       --zone=ZONE_B
   

You now have an instance group in each of two regions, each with two instances.

Create a firewall rule for the SSL load balancer

Configure the firewall to allow traffic from the load balancer and health checker to the instances.

Console

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

   Go to Firewall policies

2. Click Create firewall rule.

3. In the Name field, enter allow-ssl-lb-and-health.

4. Select the network.

5. Under Targets, select Specified target tags.

6. Set Target tags to ssl-lb.

7. Set Source filter to IPv4 ranges.

8. Set Source IPv4 ranges to 130.211.0.0/22 and 35.191.0.0/16.

9. Under Protocols and ports, set Specified protocols and ports to tcp:443.

10. Click Create.

gcloud

gcloud compute firewall-rules create allow-ssl-lb-and-health \
  --source-ranges=130.211.0.0/22,35.191.0.0/16 \
  --target-tags=ssl-lb \
  --allow=tcp:443

If 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.

gcloud compute ssl-certificates list

Configure the load balancer

Console

Start your configuration

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

   Go to Load balancing

2. Click Create load balancer.
3. For Type of load balancer, select Network Load Balancer (TCP/UDP/SSL) and click Next.
4. For Proxy or passthrough, select Proxy load balancer and click Next.
5. For Public facing or internal, select Public facing (external) and click Next.
6. For Global or single region deployment, select Best for global workloads and click Next.
7. For Load balancer generation, select Classic proxy Network Load Balancer and click Next.
8. Click Configure.

Basic configuration

Set the Name to my-ssl-lb.

Backend configuration

1. Click Backend configuration.
2. Under Backend type, select Instance groups.
3. Set the Protocol to SSL.
4. For Named port, enter ssl-lb.
5. Accept the default value for the Timeout.
6. Leave the Backend type set to Instance groups.
7. Configure the first backend:
   1. Under New backend, select instance group instance-group-a.
   2. Set Port numbers to 443.
   3. Retain the remaining default values.
8. Configure the second backend:
   1. Click Add backend.
   2. Select instance group instance-group-b.
   3. Set Port numbers to 443.
   4. Click Done.
9. Configure the health check:
   1. Under Health check, select Create health check.
   2. Set the health check Name to my-ssl-health-check.
   3. Under Protocol, select SSL.
   4. Retain the remaining default values.
   5. Click Save and continue.
10. In the Google Cloud console, verify that there is a check mark next to Backend configuration. If not, double-check that you have completed all of the steps.

Frontend configuration

1. Click Frontend configuration.
Add the first forwarding rule:
1. Enter a Name of my-ssl-lb-forwarding-rule.
2. Under Protocol, select SSL.
3. Under IP address, select Create IP address:
   1. Enter a Name of ssl-lb-static-ipv4.
   2. Click Reserve.
4. Under Certificate, select Create a new certificate.
5. Enter a Name of my-ssl-cert.
6. If you choose Upload my certificate, complete these steps:
   1. Paste in your certificate or click Upload to navigate to your certificate file.
   2. Paste in your private key or click Upload to navigate to your private key file.
7. If you choose Create Google managed certificate, enter a Domain.
   1. To enter additional domains, click Add Domain.
   2. Click Create.
8. To add certificate resources in addition to the primary SSL certificate resource, click Additional certificates. Then either select another certificate from the Certificates menu or click Create a new certificate and follow the instructions above.
1. (Optional) To create an SSL policy:
2. Under SSL policy, select Create a policy.
3. Enter a Name of my-ssl-policy.
4. For Minimum TLS Version, select TLS 1.0.
5. For Profile, select Modern. The Enabled features and Disabled features are displayed.
6. Click Save.
9. Optional: Turn on Proxy protocol.
10. Click Done.
Add the second forwarding rule:
1. Click Add frontend IP and port.
2. Enter a Name of my-ssl-lb-ipv6-forwarding-rule.
3. Set IP version to IPv6.
4. Under IP address, click Create IP address.
   1. Enter a name of ssl-lb-static-ipv6.
   2. Click Reserve.
5. Under Certificate, select my-ssl-cert.
6. To add certificate resources in addition to the primary SSL certificate resource, either select a certificate from the Certificates list or click Create a new certificate.
7. Optional: Use an SSL policy or turn on Proxy protocol.
8. Click Done.
9. Verify that there is a green check mark next to Frontend configuration in the Google Cloud console. If not, double-check that you have completed all the previous steps.
10. Click Done.

Review and finalize

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. Create a health check.

      gcloud compute health-checks create ssl my-ssl-health-check --port=443
      

2. Create a backend service.

      gcloud compute backend-services create my-ssl-lb \
          --load-balancing-scheme EXTERNAL \
          --global-health-checks \
          --protocol=SSL \
          --port-name=ssl-lb \
          --health-checks=my-ssl-health-check \
          --timeout=5m \
          --global
      

   Alternatively you can configure unencrypted communication from the load balancer to the instances by using --protocol=TCP.

3. Add instance groups to your backend service.

      gcloud compute backend-services add-backend my-ssl-lb \
          --instance-group=instance-group-a \
          --instance-group-zone=ZONE_A \
          --balancing-mode=UTILIZATION \
          --max-utilization=0.8 \
          --global
      

      gcloud compute backend-services add-backend my-ssl-lb \
          --instance-group=instance-group-b \
          --instance-group-zone=ZONE_B \
          --balancing-mode=UTILIZATION \
          --max-utilization=0.8 \
          --global
      

4. Configure your SSL certificate resource.

   If you are using self-managed certificates, you must already have at least one SSL certificate to upload. If you don't, see SSL certificates overview. When you use multiple SSL certificates, you must create them one at a time.

   If you are using self-managed SSL certificates and you don't have a private key and signed certificate, you can create and use a self-signed certificate for testing purposes.

   To create a self-managed SSL certificate resource:

      gcloud compute ssl-certificates create my-ssl-cert \
          --certificate=CRT_FILE_PATH \
          --private-key=KEY_FILE_PATH
      

   To create a Google-managed SSL certificate resource:

      gcloud compute ssl-certificates create www-ssl-cert \
          --domains=DOMAIN_1,DOMAIN_2
      

5. Configure a target SSL proxy.

   External proxy Network Load Balancers support creating a target SSL proxy that has from one to fifteen SSL certificates. Before you run this command, you must create an SSL certificate resource for each certificate.

   If you want to turn on the proxy header, set it to PROXY_V1 instead of none. You can optionally attach an SSL policy to the target proxy. First, create the policy.

      gcloud compute ssl-policies create my-ssl-policy \
          --profile=MODERN \
          --min-tls-version=1.0
      

   Then attached the policy to the target proxy.

      gcloud compute target-ssl-proxies create my-ssl-lb-target-proxy \
          --backend-service=my-ssl-lb \
          --ssl-certificates=[SSL_CERT_1][,[SSL_CERT_2],...] \
          --ssl-policy=my-ssl-policy \
          --proxy-header=NONE
      

6. Reserve global static IP addresses.

   Your customers use these IP addresses to access your load-balanced service.

      gcloud compute addresses create ssl-lb-static-ipv4 \
          --ip-version=IPV4 \
          --global
      

      gcloud compute addresses create ssl-lb-static-ipv6 \
          --ip-version=IPV6 \
          --global
      

7. Configure global forwarding rules.

   Create global forwarding rules associated with the target proxy. Replace LB_STATIC_IP and LB_STATIC_IPV6 with the IP addresses you generated in Reserve global static IP addresses.

      gcloud compute forwarding-rules create my-ssl-lb-forwarding-rule \
          --load-balancing-scheme EXTERNAL \
          --global \
          --target-ssl-proxy=my-ssl-lb-target-proxy \
          --address=LB_STATIC_IP \
          --ports=443
      

      gcloud compute forwarding-rules create my-ssl-lb-ipv6-forwarding-rule \
          --load-balancing-scheme EXTERNAL \
          --global \
          --target-ssl-proxy=my-ssl-lb-target-proxy \
          --address=LB_STATIC_IPV6 \
          --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.

Test the load balancer

In your web browser, connect to your static IP address using HTTPS. In this test setup, the instances are using self-signed certificates. Therefore, you will see a warning in your browser the first time you access a page. Click through the warning to see the actual page. Replace IP_ADDRESS with either the IPv4 or IPv6 address you created earlier.

https://IP_ADDRESS

You should see one of the hosts from the region closest to you. Reload the page until you see the other instance in that region. To see instances from the other region, stop the instances in the closest region.

Alternatively, you can use curl from the your local machine's command line. If you are using a self-signed certificate on the SSL proxy, you must also specify -k. The curl -k option allows curl to work even if you have a self-signed certificate or no certificate at all. If you have a normal certificate, you can remove that parameter. You should only use the -k parameter for testing your own site. Under normal circumstances, a valid certificate is an important security measure and certificate warnings shouldn't be ignored.

Replace IP_ADDRESS with either the IPv4 or IPv6 address you created earlier.

curl -k https://IP_ADDRESS

If you can't reach the load balancer, try the steps described under Troubleshooting your setup.

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.

PROXY protocol for retaining client connection information

The proxy Network Load Balancer ends TCP connections from the client and creates new connections to the instances. By default, the original client IP and port information is not preserved.

To preserve and send the original connection information to your instances, enable PROXY protocol version 1. This protocol sends an additional header that contains the source IP address, destination IP address, and port numbers to the instance as a part of the request.

Make sure that the proxy Network Load Balancer's backend instances are running servers that support PROXY protocol headers. If the servers are not configured to support PROXY protocol headers, the backend instances return empty responses.

If you set the PROXY protocol for user traffic, you can also set it for your health checks. If you are checking health and serving content on the same port, set the health check's --proxy-header to match your load balancer setting.

The PROXY protocol header is typically a single line of user-readable text in the following format:

PROXY TCP4 <client IP> <load balancing IP> <source port> <dest port>\r\n

The following example shows a PROXY protocol:

PROXY TCP4 192.0.2.1 198.51.100.1 15221 110\r\n

In the preceding example, the client IP is 192.0.2.1, the load balancing IP is 198.51.100.1, the client port is 15221, and the destination port is 110.

When the client IP is not known, the load balancer generates a PROXY protocol header in the following format:

PROXY UNKNOWN\r\n

Update PROXY protocol header for target proxy

The example load balancer setup on this page shows you how to enable the PROXY protocol header while creating the proxy Network Load Balancer. Use these steps to change the PROXY protocol header for an existing target proxy.

Console

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

   Go to Load balancing

2. Click Edit for your load balancer.
3. Click Frontend configuration.
4. Change the value of the Proxy protocol field to On.
5. Click Update to save your changes.

gcloud

In the following command, edit the --proxy-header field and set it to either NONE or PROXY_V1 depending on your requirement.

gcloud compute target-ssl-proxies update TARGET_PROXY_NAME \
    --proxy-header=[NONE | PROXY_V1]

Configure session affinity

These procedures show you how to update a backend service for the example SSL proxy load balancer so that the backend service uses client IP affinity.

When client IP affinity is enabled, the load balancer directs a particular client's requests to the same backend VM based on a hash created from the client's IP address and the load balancer's IP address (the external IP address of an external forwarding rule).

Console

To enable client IP session affinity:

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

   Go to Load balancing

2. Click Backends.

3. Click my-ssl-lb (the name of the backend service you created for this example) and click Edit.

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

5. Under Session affinity, select Client IP from the menu.

6. Click Update.

gcloud

Use the following command to update the my-ssl-lb backend service, specifying client IP session affinity:

gcloud compute backend-services update my-ssl-lb \
    --global \
    --session-affinity=CLIENT_IP

API

To set client IP session affinity, make a PATCH request to the backendServices/patch method.

PATCH https://www.googleapis.com/compute/v1/projects/[PROJECT_ID]/global/us-west1/backendServices/my-ssl-lb
{
  "sessionAffinity": "CLIENT_IP"
}

Enable connection draining

You can enable connection draining on backend services to ensure minimal interruption to your users when an instance that is serving traffic is terminated, removed manually, or removed by an autoscaler. To learn more about connection draining, see the Enabling Connection Draining documentation.

What's next

• See External proxy Network Load Balancer logging and monitoring for information about how monitoring works for external proxy Network Load Balancers.
• See SSL Policy overview for information about how SSL policies work.
• See Using SSL policies for information about configuring SSL policies.
  • Clean up the load balancer setup.