net-lb-app-int

Internal Application Load Balancer Module

This module allows managing Internal HTTP/HTTPS Load Balancers (L7 ILBs). It's designed to expose the full configuration of the underlying resources, and to facilitate common usage patterns by providing sensible defaults, and optionally managing prerequisite resources like health checks, instance groups, etc.

Due to the complexity of the underlying resources, changes to the configuration that involve recreation of resources are best applied in stages, starting by disabling the configuration in the urlmap that references the resources that need recreation, then doing the same for the backend service, etc.

Examples

• Examples
  • Minimal Example
  • Cross-project backend services
  • Health Checks
  • Instance Groups
  • Network Endpoint Groups (NEGs)
    • Zonal NEG creation
    • Hybrid NEG creation
    • Serverless NEG creation
    • Private Service Connect NEG creation
  • URL Map
  • SSL Certificates
  • Complex example
• Files
• Variables
• Outputs

Minimal Example

An HTTP ILB with a backend service pointing to a GCE instance group:

module "ilb-l7" {
  source     = "./fabric/modules/net-lb-app-int"
  name       = "ilb-test"
  project_id = var.project_id
  region     = "europe-west1"
  backend_service_configs = {
    default = {
      backends = [{
        group = "projects/myprj/zones/europe-west1-a/instanceGroups/my-ig"
      }]
    }
  }
  vpc_config = {
    network    = var.vpc.self_link
    subnetwork = var.subnet.self_link
  }
}
# tftest modules=1 resources=5

An HTTPS ILB needs a few additional fields:

module "ilb-l7" {
  source     = "./fabric/modules/net-lb-app-int"
  name       = "ilb-test"
  project_id = var.project_id
  region     = "europe-west1"
  backend_service_configs = {
    default = {
      backends = [{
        group = "projects/myprj/zones/europe-west1-a/instanceGroups/my-ig"
      }]
    }
  }
  protocol = "HTTPS"
  ssl_certificates = {
    certificate_ids = [
      "projects/myprj/regions/europe-west1/sslCertificates/my-cert"
    ]
  }
  vpc_config = {
    network    = var.vpc.self_link
    subnetwork = var.subnet.self_link
  }
}
# tftest modules=1 resources=5

Cross-project backend services

When using Shared VPC, this module also allows configuring cross-project backend services:

module "ilb-l7" {
  source     = "./fabric/modules/net-lb-app-int"
  name       = "ilb-test"
  project_id = "prj-host"
  region     = "europe-west1"
  backend_service_configs = {
    default = {
      project_id = "prj-svc"
      backends = [{
        group = "projects/prj-svc/zones/europe-west1-a/instanceGroups/my-ig"
      }]
    }
  }
  health_check_configs = {
    default = {
      project_id = "prj-svc"
      http = {
        port_specification = "USE_SERVING_PORT"
      }
    }
  }
  vpc_config = {
    network    = var.vpc.self_link
    subnetwork = var.subnet.self_link
  }
}
# tftest modules=1 resources=5

Health Checks

You can leverage externally defined health checks for backend services, or have the module create them for you. By default a simple HTTP health check is created, and used in backend services.

Health check configuration is controlled via the health_check_configs variable, which behaves in a similar way to other LB modules in this repository.

Defining different health checks from the default is very easy. You can for example replace the default HTTP health check with a TCP one and reference it in you backend service:

module "ilb-l7" {
  source     = "./fabric/modules/net-lb-app-int"
  name       = "ilb-test"
  project_id = var.project_id
  region     = "europe-west1"
  backend_service_configs = {
    default = {
      backends = [{
        group = "projects/myprj/zones/europe-west1-a/instanceGroups/my-ig"
      }]
      health_checks = ["custom-tcp"]
    }
  }
  health_check_configs = {
    custom-tcp = {
      tcp = { port = 80 }
    }
  }
  vpc_config = {
    network    = var.vpc.self_link
    subnetwork = var.subnet.self_link
  }
}
# tftest modules=1 resources=5

To leverage existing health checks without having the module create them, simply pass their self links to backend services and set the health_check_configs variable to an empty map:

module "ilb-l7" {
  source     = "./fabric/modules/net-lb-app-int"
  name       = "ilb-test"
  project_id = var.project_id
  region     = "europe-west1"
  backend_service_configs = {
    default = {
      backends = [{
        group = "projects/myprj/zones/europe-west1-a/instanceGroups/my-ig"
      }]
      health_checks = ["projects/myprj/global/healthChecks/custom"]
    }
  }
  health_check_configs = {}
  vpc_config = {
    network    = var.vpc.self_link
    subnetwork = var.subnet.self_link
  }
}
# tftest modules=1 resources=4

Instance Groups

The module can optionally create unmanaged instance groups, which can then be referred to in backends via their key:

module "ilb-l7" {
  source     = "./fabric/modules/net-lb-app-int"
  name       = "ilb-test"
  project_id = var.project_id
  region     = "europe-west1"
  backend_service_configs = {
    default = {
      port_name = "http"
      backends = [
        { group = "default" }
      ]
    }
  }
  group_configs = {
    default = {
      zone = "europe-west1-b"
      instances = [
        "projects/myprj/zones/europe-west1-b/instances/vm-a"
      ]
      named_ports = { http = 80 }
    }
  }
  vpc_config = {
    network    = var.vpc.self_link
    subnetwork = var.subnet.self_link
  }
}
# tftest modules=1 resources=6

Network Endpoint Groups (NEGs)

Network Endpoint Groups (NEGs) can be used as backends, by passing their id as the backend group in a backends service configuration:

module "ilb-l7" {
  source     = "./fabric/modules/net-lb-app-int"
  name       = "ilb-test"
  project_id = var.project_id
  region     = "europe-west1"
  backend_service_configs = {
    default = {
      backends = [{
        balancing_mode = "RATE"
        group          = "projects/myprj/zones/europe-west1-a/networkEndpointGroups/my-neg"
        max_rate       = { per_endpoint = 1 }
      }]
    }
  }
  vpc_config = {
    network    = var.vpc.self_link
    subnetwork = var.subnet.self_link
  }
}
# tftest modules=1 resources=5

Similarly to instance groups, NEGs can also be managed by this module which supports GCE, hybrid, serverless and Private Service Connect NEGs:

Zonal NEG creation

resource "google_compute_address" "test" {
  name         = "neg-test"
  subnetwork   = var.subnet.self_link
  address_type = "INTERNAL"
  address      = "10.0.0.10"
  region       = "europe-west1"
}

module "ilb-l7" {
  source     = "./fabric/modules/net-lb-app-int"
  name       = "ilb-test"
  project_id = var.project_id
  region     = "europe-west1"
  backend_service_configs = {
    default = {
      backends = [{
        balancing_mode = "RATE"
        group          = "my-neg"
        max_rate       = { per_endpoint = 1 }
      }]
    }
  }
  neg_configs = {
    my-neg = {
      gce = {
        zone = "europe-west1-b"
        endpoints = {
          e-0 = {
            instance   = "test-1"
            ip_address = google_compute_address.test.address
            # ip_address = "10.0.0.10"
            port = 80
          }
        }
      }
    }
  }
  vpc_config = {
    network    = var.vpc.self_link
    subnetwork = var.subnet.self_link
  }
}
# tftest modules=1 resources=8

Hybrid NEG creation

module "ilb-l7" {
  source     = "./fabric/modules/net-lb-app-int"
  name       = "ilb-test"
  project_id = var.project_id
  region     = "europe-west1"
  backend_service_configs = {
    default = {
      backends = [{ group = "my-neg" }]
    }
  }
  neg_configs = {
    my-neg = {
      hybrid = {
        zone = "europe-west1-b"
        endpoints = {
          e-0 = {
            ip_address = "10.0.0.10"
            port       = 80
          }
        }
      }
    }
  }
  vpc_config = {
    network    = var.vpc.self_link
    subnetwork = var.subnet.self_link
  }
}
# tftest modules=1 resources=7

Serverless NEG creation

module "ilb-l7" {
  source     = "./fabric/modules/net-lb-app-int"
  name       = "ilb-test"
  project_id = var.project_id
  region     = "europe-west1"
  backend_service_configs = {
    default = {
      backends = [{
        balancing_mode = "RATE"
        group          = "my-neg"
        max_rate       = { per_endpoint = 1 }
      }]
      health_checks = []
    }
  }
  health_check_configs = {}
  neg_configs = {
    my-neg = {
      cloudrun = {
        region = "europe-west1"
        target_service = {
          name = "my-run-service"
        }
      }
    }
  }
  vpc_config = {
    network    = var.vpc.self_link
    subnetwork = var.subnet.self_link
  }
}
# tftest modules=1 resources=5

Private Service Connect NEG creation

module "ilb-l7" {
  source     = "./fabric/modules/net-lb-app-int"
  name       = "ilb-test"
  project_id = var.project_id
  region     = "europe-west1"
  backend_service_configs = {
    default = {
      backends = [{
        group = "my-neg"
      }]
      health_checks = []
    }
  }
  health_check_configs = {}
  neg_configs = {
    my-neg = {
      psc = {
        region         = "europe-west1"
        target_service = "europe-west1-cloudkms.googleapis.com"
      }
    }
  }
  vpc_config = {
    network    = var.vpc.self_link
    subnetwork = var.subnet.self_link
  }
}
# tftest modules=1 resources=5

URL Map

The module exposes the full URL map resource configuration, with some minor changes to the interface to decrease verbosity, and support for aliasing backend services via keys.

The default URL map configuration sets the default backend service as the default service for the load balancer as a convenience. Just override the urlmap_config variable to change the default behaviour:

module "ilb-l7" {
  source     = "./fabric/modules/net-lb-app-int"
  name       = "ilb-test"
  project_id = var.project_id
  region     = "europe-west1"
  backend_service_configs = {
    default = {
      backends = [{
        group = "projects/myprj/zones/europe-west1-a/instanceGroups/my-ig"
      }]
    }
    video = {
      backends = [{
        group = "projects/myprj/zones/europe-west1-a/instanceGroups/my-ig-2"
      }]
    }
  }
  urlmap_config = {
    default_service = "default"
    host_rules = [{
      hosts        = ["*"]
      path_matcher = "pathmap"
    }]
    path_matchers = {
      pathmap = {
        default_service = "default"
        path_rules = [{
          paths   = ["/video", "/video/*"]
          service = "video"
        }]
      }
    }
  }
  vpc_config = {
    network    = var.vpc.self_link
    subnetwork = var.subnet.self_link
  }
}

# tftest modules=1 resources=6

SSL Certificates

Similarly to health checks, SSL certificates can also be created by the module. In this example we are using private key and certificate resources so that the example test only depends on Terraform providers, but in real use those can be replaced by external files.

resource "tls_private_key" "default" {
  algorithm = "RSA"
  rsa_bits  = 4096
}

resource "tls_self_signed_cert" "default" {
  private_key_pem = tls_private_key.default.private_key_pem
  subject {
    common_name  = "example.com"
    organization = "ACME Examples, Inc"
  }
  validity_period_hours = 720
  allowed_uses = [
    "key_encipherment",
    "digital_signature",
    "server_auth",
  ]
}

module "ilb-l7" {
  source     = "./fabric/modules/net-lb-app-int"
  name       = "ilb-test"
  project_id = var.project_id
  region     = "europe-west1"
  backend_service_configs = {
    default = {
      backends = [{
        group = "projects/myprj/zones/europe-west1-a/instanceGroups/my-ig"
      }]
    }
  }
  health_check_configs = {
    default = {
      https = { port = 443 }
    }
  }
  protocol = "HTTPS"
  ssl_certificates = {
    create_configs = {
      default = {
        # certificate and key could also be read via file() from external files
        certificate = tls_self_signed_cert.default.cert_pem
        private_key = tls_private_key.default.private_key_pem
      }
    }
  }
  vpc_config = {
    network    = var.vpc.self_link
    subnetwork = var.subnet.self_link
  }
}
# tftest modules=1 resources=8

Complex example

This example mixes group and NEG backends, and shows how to set HTTPS for specific backends.

module "ilb-l7" {
  source     = "./fabric/modules/net-lb-app-int"
  name       = "ilb-l7-test-0"
  project_id = "prj-gce"
  region     = "europe-west8"
  backend_service_configs = {
    default = {
      backends = [
        { group = "nginx-ew8-b" },
        { group = "nginx-ew8-c" },
      ]
    }
    gce-neg = {
      backends = [{
        balancing_mode = "RATE"
        group          = "neg-nginx-ew8-c"
        max_rate       = { per_endpoint = 1 }
      }]
    }
    home = {
      backends = [{
        balancing_mode = "RATE"
        group          = "neg-home-hello"
        max_rate = {
          per_endpoint = 1
        }
      }]
      health_checks      = ["neg"]
      locality_lb_policy = "ROUND_ROBIN"
      protocol           = "HTTPS"
    }
  }
  group_configs = {
    nginx-ew8-b = {
      zone = "europe-west8-b"
      instances = [
        "projects/prj-gce/zones/europe-west8-b/instances/nginx-ew8-b"
      ]
      named_ports = { http = 80 }
    }
    nginx-ew8-c = {
      zone = "europe-west8-c"
      instances = [
        "projects/prj-gce/zones/europe-west8-c/instances/nginx-ew8-c"
      ]
      named_ports = { http = 80 }
    }
  }
  health_check_configs = {
    default = {
      http = {
        port = 80
      }
    }
    neg = {
      https = {
        host = "hello.home.example.com"
        port = 443
      }
    }
  }
  neg_configs = {
    neg-nginx-ew8-c = {
      gce = {
        zone = "europe-west8-c"
        endpoints = {
          e-0 = {
            instance   = "nginx-ew8-c"
            ip_address = "10.24.32.26"
            port       = 80
          }
        }
      }
    }
    neg-home-hello = {
      hybrid = {
        zone = "europe-west8-b"
        endpoints = {
          e-0 = {
            ip_address = "192.168.0.3"
            port       = 443
          }
        }
      }
    }
  }
  urlmap_config = {
    default_service = "default"
    host_rules = [
      {
        hosts        = ["*"]
        path_matcher = "gce"
      },
      {
        hosts        = ["hello.home.example.com"]
        path_matcher = "home"
      }
    ]
    path_matchers = {
      gce = {
        default_service = "default"
        path_rules = [
          {
            paths   = ["/gce-neg", "/gce-neg/*"]
            service = "gce-neg"
          }
        ]
      }
      home = {
        default_service = "home"
      }
    }
  }
  vpc_config = {
    network    = "projects/prj-host/global/networks/shared-vpc"
    subnetwork = "projects/prj-host/regions/europe-west8/subnetworks/gce"
  }
}
# tftest modules=1 resources=14

Files

name	description	resources
backend-service.tf	Backend service resources.	google_compute_region_backend_service
groups.tf	None	google_compute_instance_group
health-check.tf	Health check resource.	google_compute_health_check
main.tf	Module-level locals and resources.	google_compute_forwarding_rule · google_compute_network_endpoint · google_compute_network_endpoint_group · google_compute_region_network_endpoint_group · google_compute_region_ssl_certificate · google_compute_region_target_http_proxy · google_compute_region_target_https_proxy
outputs.tf	Module outputs.
urlmap.tf	URL map resources.	google_compute_region_url_map
variables-backend-service.tf	Backend services variables.
variables-health-check.tf	Health check variable.
variables-urlmap.tf	URLmap variable.
variables.tf	Module variables.
versions.tf	Version pins.

Variables

name	description	type	required	default
name	Load balancer name.	string	✓
project_id	Project id.	string	✓
region	The region where to allocate the ILB resources.	string	✓
vpc_config	VPC-level configuration.	object({…})	✓
address	Optional IP address used for the forwarding rule.	string		null
backend_service_configs	Backend service level configuration.	map(object({…}))		{}
description	Optional description used for resources.	string		"Terraform managed."
global_access	Allow client access from all regions.	bool		null
group_configs	Optional unmanaged groups to create. Can be referenced in backends via key or outputs.	map(object({…}))		{}
health_check_configs	Optional auto-created health check configurations, use the output self-link to set it in the auto healing policy. Refer to examples for usage.	map(object({…}))		{…}
labels	Labels set on resources.	map(string)		{}
neg_configs	Optional network endpoint groups to create. Can be referenced in backends via key or outputs.	map(object({…}))		{}
network_tier_premium	Use premium network tier. Defaults to true.	bool		true
ports	Optional ports for HTTP load balancer, valid ports are 80 and 8080.	list(string)		null
protocol	Protocol supported by this load balancer.	string		"HTTP"
service_directory_registration	Service directory namespace and service used to register this load balancer.	object({…})		null
ssl_certificates	SSL target proxy certificates (only if protocol is HTTPS).	object({…})		{}
urlmap_config	The URL map configuration.	object({…})		{…}

Outputs

name	description	sensitive
address	Forwarding rule address.
backend_service_ids	Backend service resources.
backend_service_names	Backend service resource names.
forwarding_rule	Forwarding rule resource.
group_ids	Autogenerated instance group ids.
health_check_ids	Autogenerated health check ids.
id	Fully qualified forwarding rule id.
neg_ids	Autogenerated network endpoint group ids.