Google Distributed Cloud clusters can run load balancers in one of three ways: integrated, bundled, or manual. With the integrated option, an Google Distributed Cloud cluster uses the F5 BIG-IP load balancer.
With the bundled option, Google Distributed Cloud provides and manages the load balancer. You do not have to get a license for a load balancer, and the amount of setup that you have to do is minimal.
Advantages of bundled load balancing
Bundled load balancing provides these advantages compared to manual load balancing:
A single team can be in charge of both cluster creation and load balancer configuration. For example, a cluster administration team would not have to rely on a separate networking team to acquire, run, and configure the load balancer ahead of time.
Google Distributed Cloud automatically configures virtual IP addresses (VIPs) on the load balancer. At cluster creation time, Google Distributed Cloud configures the load balancer with VIPs for the Kubernetes API server, the ingress service, and the cluster add-ons. As clients create Services of type LoadBalancer, Google Distributed Cloud automatically configures the Service VIPs on the load balancer.
Dependencies among organizations, groups, and administrators are reduced. In particular, the group that manages a cluster is less dependent on the group that manages the network.
With the manual option, Google Distributed Cloud uses a different load balancer of your choice. Manual load balancing requires that you do more configuration than with the integrated option.
If you choose to use the F5 BIG-IP load balancer, you need to have a user role that has sufficient permissions to set up and manage the load balancer. Either the Administrator role or the Resource Administrator role is sufficient.
This topic describes setting aside IP addresses and nodePort values for later
use. The idea is that you choose the IP addresses and nodePort values that you
want to use for load balancing and for your cluster nodes. But you don't do
anything with the addresses and nodePort values at this point. Later, when you
are ready to install Google Distributed Cloud, you will need the addresses and
nodePort values to fill in your cluster configuration file.
Setting aside virtual IP addresses
Regardless of which load balancing mode, you must set aside several virtual IP addresses (VIPs) that you intend to use for load balancing. With integrated and bundled mode, you specify these VIPs in your cluster configuration file, and Google Distributed Cloud automatically configures the F5 BIG-IP or Seesaw load balancer to use the VIPs. With manual mode, you must manually configure your load balancer to use the VIPs.
For your admin cluster, you must set aside this VIP:
- VIP for Kubernetes API server
For each user cluster you intend to create, you must set aside these VIPs:
- VIP for the Kubernetes API server
- VIP for the ingress service
If you intend to use add-ons in your admin cluster, you must set aside a VIP for the addon service in the admin cluster.
For example, suppose you intend to have two user clusters, and you intend to use addons. Then you would need two VIPs for your admin cluster and two VIPs for each of your user clusters. So you would need to set aside six VIPs.
Setting aside node IP addresses
With integrated or bundled mode, you can use an existing Dynamic Host Configuration Protocol (DHCP) server to provide IP addresses for your cluster nodes, or you can specify static IP addresses for nodes. With manual mode, you cannot use DHCP. You must specify static IP addresses for your nodes.
If you choose to use static IP addresses, you must set aside enough addresses for the nodes in the admin cluster and the nodes in all the user clusters you intend to create. For details about how many node IP addresses to set aside, see Creating an admin cluster.
Setting aside nodePort values
In Google Distributed Cloud clusters, the Kubernetes API server, the ingress
service, and the addon service are implemented as
Kubernetes Services of type NodePort.
With integrated or bundled load balancing mode, Google Distributed Cloud chooses
the nodePort values for these Services automatically. With manual load
balancing mode, you must specify the nodePort values to be used for these
Services. For more information, see
Setting aside nodePort values.
Configuring the load balancer
With integrated or bundled load balancing mode, Google Distributed Cloud automatically configures the load balancer with the VIPs that you specify in the cluster configuration file. With manual mode, you must configure your load balancer with the VIPs you have chosen. How you configure your load balancer depends on which load balancer you are using. For more information, see Enabling manual load balancing.
Summary of preparing for load balancing
The following table summarizes what you must do to prepare for load balancing in integrated and manual mode:
| Integrated/Bundled mode | Manual mode | |
|---|---|---|
| Choose VIPs before you create your clusters. | Yes | Yes |
| Choose node IP addresses before you create your clusters. | No, if using DHCP. Yes, if using static IP addresses. | Yes |
Choose nodePort values before you create your clusters. | No | Yes |
| Manually configure your load balancer | No | Yes |
Creating Services in your cluster
After your user cluster is running, you might want to create Kubernetes Services and expose them to external clients.
Regardless of whether you are using integrated, bundled or manual load balancing mode, you can expose Services to external clients by using Ingress objects.
With integrated or bundled load balancing mode, you can create a Service of type
LoadBalancer and specify a VIP for the Service. Google Distributed Cloud
automatically configures the VIP on the load balancer.
With manual load balancing mode, you cannot expose a Service of type
LoadBalancer to external clients. Instead, you can use these steps
to expose a Service to external clients:
Create a Service of type NodePort.
Choose a VIP for your Service.
Manually configure your load balancer so that traffic sent to the VIP is forwarded to your Service.
The following table summarizes the kinds of Services you can expose in different modes:
| Integrated/Bundled mode | Manual mode | |
|---|---|---|
| Expose Services to external clients by using Ingress objects. | Yes | Yes |
Expose Services of type ClusterIP to internal clients. | Yes | Yes |
Expose Services of type NodePort to external clients. | Yes | Yes |
Expose Services of type LoadBalancer to external clients. | Yes | No |