Setting up Internal HTTP(S) Load Balancing with Shared VPC

This document provides instructions for configuring Internal HTTP(S) Load Balancing on a Shared VPC network.

If you don't want to use a Shared VPC network, see Setting up Internal HTTP(S) Load Balancing.

Before you begin

  1. Read Shared VPC overview.
  2. Read Internal HTTP(S) Load Balancing overview, including the Shared VPC architectures and Limitations sections.

Permissions

Setting up internal HTTP(S) load balancer for Shared VPC requires some up-front setup and provisioning by an administrator. Once this is done, a service project owner can deploy the load balancer and backends using the resources provisioned by the administrator.

This section summarizes the permissions required to follow this guide to set up an internal HTTP(S) load balancer on a Shared VPC network.

Set up Shared VPC

The following roles are required to:

  1. Perform one-off administrative tasks such as setting up the Shared VPC and enabling a host project.
  2. Perform administrative tasks that must be repeated every time you want to onboard a new service project. This includes attaching the service project, provisioning and configuring networking resources, and granting access to the service project administrator.

These tasks must be performed in the Shared VPC host project. We recommend that the Shared VPC Admin also be the owner of the Shared VPC host project. This automatically grants the Network Admin and Security Admin roles.

Task Required role
Set up Shared VPC, enable host project, and grant access to service project administrators Shared VPC Admin
Create subnets in the Shared VPC and grant access to service project administrators Network Admin
Add and remove firewall rules Security Admin

Once the subnets have been provisioned, the host project owner must grant the Network User role in the host project to anyone (typically service project administrators or developers) who needs to use these resources.

Task Required role
Use VPCs and subnets belonging to the host project Network User

This role can be granted on the project level or for individual subnets. We recommend that you grant the role on individual subnets. Granting the role on the project provides access to all current and future subnets in the VPC of the host project.

Deploy and update internal HTTP(S) load balancer and backends

Service project administrators need the following roles in the service project to create load balancing resources and backends. The permissions granted by these roles are granted automatically if you are a service project owner or editor.

Roles granted in the service project
Task Required role
Create load balancer components Network Admin
Create instances Instance Admin
Create and modify SSL certificates Security Admin

For more information, see the following guides:

Setup overview

As shown in the diagram, this example creates an internal HTTP(S) load balancer on a Shared VPC network deployment.

Internal HTTP(S) Load Balancing on Shared VPC
Internal HTTP(S) Load Balancing on Shared VPC

The internal HTTP(S) load balancer's networking resources such as the proxy-only subnet and the subnet for the backend instances are created in the host project. The firewall rules for the backend instances are also created in the host project.

The load balancer's forwarding rule, target proxy, URL map, backend service, and backend instances are created in the service project.

Prerequisites

The steps in this section do not need to be performed every time you want to create an internal HTTP(S) load balancer. However, you must ensure that you have access to the resources described here before you proceed to creating the load balancer.

Setting up Shared VPC with a host and service project

  1. Set up Shared VPC.
  2. Enable a host project.
  3. Attach a service project.

The rest of these instructions assume that you have already set up Shared VPC. This involves setting up IAM policies for your organization, and designating the host and service projects.

Do not proceed until you have set up Shared VPC and enabled the host and service projects.

Configuring the network and subnets in the host project

You need a Shared VPC network with two subnets: one for the load balancer's frontend and backends, and the other for the load balancer's proxies.

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

  • Network. The network is named lb-network.

  • Subnet for load balancer frontend and backends. A subnet named lb-frontend-and-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 subnet for the load balancer's frontend and backends

This step does not need to be performed every time you want to create an internal HTTP(S) load balancer. You only need to ensure that the service project has access to a subnet in the Shared VPC network (in addition to the proxy-only subnet).

Cloud Console

  1. In the Google Cloud Console, go to the VPC networks page.
    Go to the VPC networks page
  2. Click Create VPC network.
  3. For the Name, enter lb-network.
  4. In the Subnets section:
    • Set the Subnet creation mode to Custom.
    • In the New subnet section, enter the following information:
      • Name: lb-frontend-and-backend-subnet
      • Region: us-west1
      • IP address range: 10.1.2.0/24
    • Click Done.
  5. Click Create.

gcloud

  1. Create a 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:

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

Configure the proxy-only subnet

The proxy-only subnet is used by all internal HTTP(S) load balancers in the us-west1 region, in the lb-network VPC network. There can only be one active proxy-only subnet per region, per network.

Do not perform this step if there is already a proxy-only subnet reserved for internal HTTP(S) load balancers in the us-west1 region in this network.

Cloud Console

  1. In the Cloud Console, go to the VPC networks page.
    Go to the VPC networks page
  2. Click the name of the Shared VPC network: lb-network.
  3. Click Add subnet.
  4. For the Name, enter proxy-only-subnet.
  5. For the Region, select us-west1.
  6. Set Reserve for Internal HTTP(S) Load Balancing to On.
  7. For the 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=INTERNAL_HTTPS_LOAD_BALANCER \
  --role=ACTIVE \
  --region=us-west1 \
  --network=lb-network \
  --range=10.129.0.0/23

Give service project admins access to the backend subnet

Service project administrators require access to the lb-frontend-and-backend-subnet subnet so they can choose a frontend IP address for the load balancer and provision the load balancer's backends.

A Shared VPC Admin must grant access to the backend subnet to service project administrators (or developers who will deploy resources and backends that use the subnet). For instructions, see Service project admins for some subnets.

Configuring firewall rules in the host project

This step does not need to be performed every time you want to create an internal HTTP(S) load balancer. This is a one-off step that must be performed by the host project administrator, in the host project.

This example uses the following firewall rules:

  • fw-allow-ssh. An ingress rule, applicable to the instances being load balanced, that allows incoming SSH connectivity on TCP port 22 from any address. You can choose a more restrictive source IP range for this rule; for example, you can specify just the IP ranges of the system from which you initiate SSH sessions. This example uses the target tag allow-ssh to identify the virtual machines (VMs) to which the firewall rule applies.

  • 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 instances to which it should apply.

  • 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 internal HTTP(S) load balancer's managed proxies. This example uses the target tag load-balanced-backend to identify the instances to which it should apply.

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

Cloud Console

  1. In the Cloud Console, go to the Firewall rules page.
    Go to the Firewall rules page
  2. Click Create firewall rule to create the rule to allow incoming SSH connections:
    • Name: fw-allow-ssh
    • Network: lb-network
    • Direction of traffic: ingress
    • Action on match: allow
    • Targets: Specified target tags
    • Target tags: allow-ssh
    • Source filter: IP ranges
    • Source IP ranges: 0.0.0.0/0
    • Protocols and ports:
      • Choose Specified protocols and ports.
      • Check tcp and type 22 for the port number.
  3. Click Create.
  4. Click Create firewall rule a second time 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: IP ranges
    • Source IP ranges: 130.211.0.0/22 and 35.191.0.0/16
    • Protocols and ports:
      • Choose Specified protocols and ports.
      • Check tcp and enter 80.
        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.
  5. Click Create.
  6. Click Create firewall rule a third time 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: IP ranges
    • Source IP ranges: 10.129.0.0/23
    • Protocols and ports:
      • Choose Specified protocols and ports.
      • Check tcp and type 80, 443, 8080 for the port numbers.
  7. Click Create.

gcloud

  1. Create the fw-allow-ssh firewall rule to allow SSH connectivity to VMs with the network tag allow-ssh. When you omit source-ranges, Google Cloud interprets the rule to mean any source.

    gcloud compute firewall-rules create fw-allow-ssh \
        --network=lb-network \
        --action=allow \
        --direction=ingress \
        --target-tags=allow-ssh \
        --rules=tcp:22
    
  2. 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
    
  3. Create the fw-allow-proxies rule to allow the internal HTTP(S) load balancer's proxies to connect to your backends.

    gcloud compute firewall-rules create fw-allow-proxies \
      --network=lb-network \
      --action=allow \
      --direction=ingress \
      --source-ranges=10.129.0.0/23 \
      --target-tags=load-balanced-backend \
      --rules=tcp:80,tcp:443,tcp:8080
    

Configuring the internal HTTP(S) load balancer in the service project

This section shows you how to set up the load balancer and backends. These steps should be carried out by the service project administrator (or a developer operating within the service project) and do not require involvement from the host project administrator. The steps in this section are largely similar to the standard steps to set up Internal HTTP(S) Load Balancing.

This section shows the configuration required to set up load balancing for services running on either Compute Engine VMs or on pods in a Google Kubernetes Engine cluster. Clients connect to the IP address and port that you configure in the load balancer's forwarding rule. When clients send traffic to this IP address and port, their requests are forwarded to the backend instances (Compute Engine VMs or GKE pods) according to the internal HTTP(S) load balancer's URL map.

The example on this page explicitly sets a reserved internal IP address for the internal HTTP(S) load balancer's forwarding rule, rather than allowing an ephemeral internal IP address to be allocated. As a best practice, we recommend reserving IP addresses for forwarding rules.

Creating a managed instance group

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 internal HTTP(S) load balancer. Traffic from clients is load balanced to these backend servers. For demonstration purposes, backends serve their own hostnames.

Cloud Console

  1. In the Cloud Console, go to the Instance groups page.
    Go to the Instance groups page
  2. Click Create instance group.
  3. Choose New managed instance group on the left.
  4. For the Name, enter l7-ilb-backend-example.
  5. Under Location, select Single zone.
  6. For the Region, select us-west1.
  7. For the Zone, select us-west1-a.
  8. Under Instance template, select Create a new instance template.

    1. For the Name, enter l7-ilb-backend-template.
    2. Ensure that the Boot disk is set to a Debian image, such as Debian GNU/Linux 9 (stretch). These instructions use commands that are only available on Debian, such as apt-get. If you need to change the Boot disk, click Change.
      1. Under Operating System, select Debian.
      2. Under Version, select one of the available Debian images such as Debian GNU/Linux 9 (stretch).
      3. Click Select.
    3. Under Management, security, disks, networking, sole tenancy, on the Management tab, insert 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://169.254.169.254/computeMetadata/v1/instance/name)"
      echo "Page served from: $vm_hostname" | \
      tee /var/www/html/index.html
      systemctl restart apache2'
      
    4. Under Networking, select Networks shared with me (from host project: HOST_PROJECT_ID).

    5. Select lb-network as the Network, and for the Subnet, select lb-frontend-and-backend-subnet.

    6. Add the following network tags: allow-ssh and load-balanced-backend.

    7. Click Save and continue.

  9. Specify the number of instances that you want to create in the group.

    For this example, under Autoscaling mode, you can select:

    • Don't autoscale
    • Under Number of instances, enter 2

    Optionally, in the Autoscaling section of the UI, you can configure the instance group to automatically add or remove instances based on instance CPU usage.

  10. Click Create to create the new instance group.

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-ilb-backend-template \
    --region=us-west1 \
    --network=projects/HOST_PROJECT_ID/global/networks/lb-network \
    --subnet=projects/HOST_PROJECT_ID/regions/us-west1/subnetworks/lb-frontend-and-backend-subnet \
    --tags=allow-ssh,load-balanced-backend \
    --image-family=debian-9 \
    --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://169.254.169.254/computeMetadata/v1/instance/name)"
    echo "Page served from: $vm_hostname" | \
    tee /var/www/html/index.html
    systemctl restart apache2' \
    --project SERVICE_PROJECT_ID
    
  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-ilb-backend-example \
        --zone=us-west1-a \
        --size=2 \
        --template=l7-ilb-backend-template \
        --project SERVICE_PROJECT_ID
    

Configuring the load balancer

This example shows you how to create the following internal HTTP(S) load balancer resources:

  • HTTP health check
  • Backend service with a managed instance group as the backend
  • A URL map
  • SSL certificate (required only for HTTPS)
  • Target proxy
  • Forwarding rule

Proxy availability

Depending on the number of service projects that are using the same Shared VPC network, you may reach quotas or limits more quickly than in the network deployment model where each Google Cloud project hosts its own network.

For example, sometimes Google Cloud regions don't have enough proxy capacity for a new internal HTTP(S) load balancer. If this happens, the 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:

  • Wait for the capacity issue to be resolved.
  • Contact your Google Cloud sales team to increase these limits.

Cloud Console

Select a load balancer type

  1. In the Cloud Console, go to the Load balancing page.
    Go to the Load balancing page
  2. Under HTTP(S) Load Balancing, click Start configuration.
  3. Select Only between my VMs. This setting means that the load balancer is internal.
  4. Click Continue.

Prepare the load balancer

  1. For the Name of the load balancer, enter l7-ilb-shared-vpc.
  2. For the Region, select us-west1.
  3. For the Network, select Networks shared with me (from host project: HOST_PROJECT_ID).
    1. From the dropdown, select lb-network.
      If you see a Proxy-only subnet required in Shared VPC network warning, confirm that the host project admin has created the proxy-only-subnet in the us-west1 region in the lb-network Shared VPC network. Load balancer creation will succeed even if you do not have permission to view the proxy-only subnet on this page.
  4. Keep the window open to continue.

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-ilb-backend-service.
  4. Set the Backend type to Instance groups.
  5. In the New backend section:
    1. Set the Instance group to l7-ilb-backend-example.
    2. Set the Port numbers to 80.
    3. Set the Balancing mode to Utilization.
    4. Click Done.
  6. In the Health check section, choose Create a health check with the following parameters:
    1. Name: l7-ilb-basic-check
    2. Protocol: HTTP
    3. Port: 80
  7. Click Save and Continue.
  8. Click Create.

Configure the URL map

Click Routing rules. Ensure that the l7-ilb-backend-service is the only backend service for any unmatched host and any unmatched path.

For information about traffic management, see Setting up traffic management.

Configure the frontend

For HTTP:

  1. Click Frontend configuration.
  2. Click Add frontend IP and port.
  3. Set the Name to l7-ilb-forwarding-rule.
  4. Set the Protocol to HTTP.
  5. Set the Subnetwork to lb-frontend-and-backend-subnet.
    Don't select the proxy-only subnet for the frontend even if it is an option in the dropdown list.
  6. Under Internal IP, select Reserve a static internal IP address.
  7. In the panel that appears, provide the following details:
    1. Name: l7-ilb-ip
    2. In the Static IP address section, select Let me choose.
    3. In the Custom IP address section, enter 10.1.2.99.
    4. Click Reserve.
  8. Set the Port to 80.
  9. 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 internal HTTP(S) load balancers.

  1. Click Frontend configuration.
  2. Click Add frontend IP and port.
  3. In the Name field, enter l7-ilb-forwarding-rule.
  4. In the Protocol field, select HTTPS (includes HTTP/2).
  5. Set the Subnetwork to lb-frontend-and-backend-subnet.
    Don't select the proxy-only subnet for the frontend even if it is an option in the dropdown list.
  6. Under Internal IP, select Reserve a static internal IP address.
  7. In the panel that appears provide the following details:
    1. Name: l7-ilb-ip
    2. In the Static IP address section, select Let me choose.
    3. In the Custom IP address section, enter 10.1.2.99.
    4. Click Reserve.
  8. Ensure that the Port is set to 443, to allow HTTPS traffic.
  9. Click the Certificate drop-down list.
    1. If you already have a self-managed SSL certificate resource you want to use as the primary SSL certificate, select it from the drop-down menu.
    2. Otherwise, select Create a new certificate.
      1. Fill in a Name of l7-ilb-cert.
      2. In the appropriate fields upload your PEM-formatted files:
        • Public key certificate
        • Certificate chain
        • Private key
      3. Click Create.
  10. To add certificate resources in addition to the primary SSL certificate resource:
    1. Click Add certificate.
    2. Select a certificate from the Certificates list or click Create a new certificate and follow the instructions above.
  11. Click Done.

Review and finalize the configuration

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-ilb-basic-check \
       --region=us-west1 \
       --use-serving-port \
       --project SERVICE_PROJECT_ID
    
  2. Define the backend service with the gcloud compute backend-services create command.

    gcloud compute backend-services create l7-ilb-backend-service \
      --load-balancing-scheme=INTERNAL_MANAGED \
      --protocol=HTTP \
      --health-checks=l7-ilb-basic-check \
      --health-checks-region=us-west1 \
      --region=us-west1 \
      --project SERVICE_PROJECT_ID
    
  3. Add backends to the backend service with the gcloud compute backend-services add-backend command.

    gcloud compute backend-services add-backend l7-ilb-backend-service \
      --balancing-mode=UTILIZATION \
      --instance-group=l7-ilb-backend-example \
      --instance-group-zone=us-west1-a \
      --region=us-west1 \
      --project SERVICE_PROJECT_ID
    
  4. Create the URL map with the gcloud compute url-maps create command.

    gcloud compute url-maps create l7-ilb-map \
      --default-service=l7-ilb-backend-service \
      --region=us-west1 \
      --project SERVICE_PROJECT_ID
    
  5. Create the target proxy.

    For HTTP:

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

    gcloud compute target-http-proxies create l7-ilb-proxy \
      --url-map=l7-ilb-map \
      --url-map-region=us-west1 \
      --region=us-west1 \
      --project SERVICE_PROJECT_ID
    

    For HTTPS:

    For information about how to create SSL certificate resources, see SSL certificates. Google-managed certificates aren't currently supported with internal HTTP(S) load balancers.

    Assign your filepaths to variable names.

    export LB_CERT=path to PEM-formatted file
    
    export LB_PRIVATE_KEY=path to PEM-formatted file
    

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

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

    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-ilb-proxy \
      --url-map=l7-ilb-map \
      --region=us-west1 \
      --ssl-certificates=l7-ilb-cert \
      --project SERVICE_PROJECT_ID
    
  6. Create the forwarding rule.

    For custom networks, you must reference the subnet in the forwarding rule.

    For the forwarding rule's IP address, use the lb-frontend-and-backend-subnet. If you try to use the proxy-only subnet, forwarding rule creation fails.

    For HTTP:

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

    gcloud compute forwarding-rules create l7-ilb-forwarding-rule \
      --load-balancing-scheme=INTERNAL_MANAGED \
      --network=projects/HOST_PROJECT_ID/global/networks/lb-network \
      --subnet=projects/HOST_PROJECT_ID/regions/us-west1/subnetworks/lb-frontend-and-backend-subnet \
      --address=10.1.2.99 \
      --ports=80 \
      --region=us-west1 \
      --target-http-proxy=l7-ilb-proxy \
      --target-http-proxy-region=us-west1 \
      --project SERVICE_PROJECT_ID
    

    For HTTPS:

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

    gcloud compute forwarding-rules create l7-ilb-forwarding-rule \
      --load-balancing-scheme=INTERNAL_MANAGED \
      --network=projects/HOST_PROJECT_ID/global/networks/lb-network \
      --subnet=projects/HOST_PROJECT_ID/regions/us-west1/subnetworks/lb-frontend-and-backend-subnet \
      --address=10.1.2.99 \
      --ports=443 \
      --region=us-west1 \
      --target-https-proxy=l7-ilb-proxy \
      --target-https-proxy-region=us-west1 \
      --project SERVICE_PROJECT_ID
    

Testing

Creating a VM instance to test connectivity

Clients can be located in either the host project or any connected service project. In this example, you test that the load balancer is working by deploying a client VM in a service project. The client must use the same Shared VPC network and be in the same region as the load balancer.

gcloud compute instances create l7-ilb-client-us-west1-a \
    --image-family=debian-9 \
    --image-project=debian-cloud \
    --subnet=projects/HOST_PROJECT_ID/regions/us-west1/subnetworks/lb-frontend-and-backend-subnet \
    --zone=us-west1-a \
    --tags=allow-ssh \
    --project SERVICE_PROJECT_ID

Testing the load balancer

Log in to the instance that you just created and test that HTTP(S) services on the backends are reachable via the internal HTTP(S) load balancer's forwarding rule IP address, and traffic is being load balanced across the backend instances.

Connecting via SSH to each client instance

gcloud compute ssh l7-ilb-client-us-west1-a \
    --zone=us-west1-a

Verifying that the IP is serving its hostname

curl 10.1.2.99

For HTTPS testing, replace curl with:

curl -k -s 'https//:10.1.2.99:443'

The -k flag causes curl to skip certificate validation.

Running 100 requests and confirming that they are load balanced

For HTTP:

{
  RESULTS=
  for i in {1..100}
  do
      RESULTS="$RESULTS:$(curl --silent 10.1.2.99)"
  done
  echo "***"
  echo "*** Results of load-balancing to 10.1.2.99: "
  echo "***"
  echo "$RESULTS" | tr ':' '\n' | grep -Ev "^$" | sort | uniq -c
  echo
}

For HTTPS:

{
  RESULTS=
  for i in {1..100}
  do
      RESULTS="$RESULTS:$(curl -k -s 'https://:10.1.2.99:443')"
  done
  echo "***"
  echo "*** Results of load-balancing to 10.1.2.99: "
  echo "***"
  echo "$RESULTS" | tr ':' '\n' | grep -Ev "^$" | sort | uniq -c
  echo
}

What's next