Configure a regional Cloud Load Balancing backend service in Application Design Center

You create a load balancer in your application by configuring and connecting distinct Cloud Load Balancing frontend and backend components. The separate components help you apply distinct controls for external and internal traffic, and prevent direct access to data.

The regional Cloud Load Balancing backend component helps you manage load balancer traffic distribution settings, including the protocol used to connect to backends, session settings, health checks, and timeouts. These settings provide fine-grained control over how your load balancer behaves. You can configure the following backends:

• Serverless NEG: A list of serverless Cloud Run or Cloud Run functions applications as backends.

• Managed Instance Group (MIG): A list of Compute Engine instance groups as backends.

For more information, see Backend services overview.

This document describes the connections and parameters you can configure when using App Design Center to create a regional Cloud Load Balancing backend service. The configuration parameters are based on the terraform-google-regional-lb-http Terraform module.

Component connections

To create a complete Cloud Load Balancing component, you must connect your regional Cloud Load Balancing backend to at least one regional Cloud Load Balancing frontend. Connected Cloud Load Balancing components are displayed as a group in the design canvas.

The following table includes the components that you can connect to a regional Cloud Load Balancing backend, and the resulting updates to your application and its generated Terraform code.

Connected component	Application updates	Background information
Cloud Run	The load balancer can distribute incoming traffic to the Cloud Run service. The Cloud Run service is added as a backend endpoint in the Cloud Load Balancing serverless NEG backends configuration.	Set up a regional external Application Load Balancer with Cloud Run
Regional Cloud Load Balancing frontend (required)	The Cloud Load Balancing frontend, which handles incoming requests, is linked to the Cloud Load Balancing backend, which processes the requests. The backend service information is added to the frontend URL map input.	URL maps overview
Compute Engine MIG	The load balancer can distribute incoming traffic to the Compute Engine MIG. The Compute Engine MIG is added to the Cloud Load Balancing backend service groups field.	Set up a regional external Application Load Balancer with VM instance group backends

Required configuration parameters

If your template includes a regional Cloud Load Balancing backend component, you must configure the following parameters before you deploy.

Parameter name	Description and constraints	Background information
Project ID	The project where you want to deploy the Cloud Load Balancing backend service.	Configure components
Region	The region where the load balancer backend service is created.	region
Name	Name for the load balancer backend service.	name

Optional configuration parameters

The following parameters are optional. To display advanced parameters, in the Configuration area, select Show advanced fields.

Feature	Parameter name	Description and constraint information	Background information
Host Path Mappings	Host	Configure URL maps	URL maps overview
	Path	Configure URL maps	URL maps overview
	Load Balancing Scheme	loadBalancingScheme	Backend services overview
Serverless NEG backends	Region	region	Serverless network endpoint groups overview
	Type	networkEndpointType	Serverless network endpoint groups overview
	Service Name	appEngine.service	Serverless network endpoint groups overview
	Service Version	appEngine.version	Serverless network endpoint groups overview
	Capacity Scaler	backends[].capacityScaler	Capacity Scaler
Groups	Group	backends[].group	Backends
	Description	A description for the backends group.	backends[].description
	Balancing Mode	backends[].balancingMode	Balancing modes and target capacity settings
	Capacity Scaler	backends[].capacityScaler	Capacity scaler
	Max Connections	backends[].maxConnections	Connection balancing mode
	Max Connections Per Instance	backends[].maxConnectionsPerInstance	Connection balancing mode
	Max Connections Per Endpoint	backends[].maxConnectionsPerEndpoint	Connection balancing mode
	Max Rate	backends[].maxRate	Rate balancing mode
	Max Rate Per Instance	backends[].maxRatePerInstance	Rate balancing mode
	Max Rate Per Endpoint	backends[].maxRatePerEndpoint	Rate balancing mode
	Max Utilization	backends[].maxUtilization	Utilization balancing mode
	Protocol	protocol	Protocol to the backends
	Port Name	portName	Named ports
	Description	A description for the backend service.	description
Health Check	Host	http2HealthCheck.host	Additional flags for HTTP, HTTPS, and HTTP/2 health checks
	Request Path	http2HealthCheck.requestPath	Success criteria for HTTP, HTTPS, and HTTP/2
	Request	sslHealthCheck.request	ASuccess criteria for SSL and TCP
	Response	sslHealthCheck.response	Additional flags for HTTP, HTTPS, and HTTP/2 health checks
	Port	http2HealthCheck.port	Health check categories, protocols, and ports
	Port Name	http2HealthCheck.portName	Named ports
	Proxy Header	http2HealthCheck.proxyHeader	Headers
	Port Specification	http2HealthCheck.portSpecification	Port specification flags
	Protocol	The protocol that Google Cloud uses to probe the backends. For example, http2.	Health check categories, protocols, and ports
	Check Interval Sec	checkIntervalSec	Probes
	Timeout Sec	timeoutSec	Probes
	Healthy Threshold	healthyThreshold	Health state
	Unhealthy Threshold	unhealthyThreshold	Health state
	Logging	logConfig.enable	Health check logging information
	Firewall Networks	network	Configure firewall rules
	Firewall Projects	Names of the projects to create firewall rules in.	Configure firewall rules
	Target Tags	targetTags[]	Restrict which clients can send traffic to the load balancer
	Target Service Accounts	targetServiceAccounts[]	Source and target filtering by service account
	Firewall Source Ranges	sourceRanges[]	Configure firewall rules
	Connection Draining Timeout Sec	connectionDraining.drainingTimeoutSec	Enable connection draining
	Enable CDN	enableCDN	Cloud CDN overview
	Session Affinity	sessionAffinity	Session affinity
	Affinity Cookie TTL Sec	affinityCookieTtlSec	Generated cookie affinity
	Locality LB Policy	localityLbPolicy	Load balancing locality policy
	Security Policy	securityPolicy	Google Cloud Armor
	Timeout Sec	timeoutSec	Backend service timeout

What's next

You must connect your backend component to a frontend component. To configure the frontend component, see Configure a regional Cloud Load Balancing frontend in Application Design Center.