# VLAN Attachment module

This module allows for the provisioning of [HA VPN over Interconnect](https://cloud.google.com/network-connectivity/docs/interconnect/concepts/ha-vpn-interconnect?hl=it). Specifically, this module creates a VPN gateway, a configurable number of tunnels, and all the resources required to established IPSec and BGP with the peer routers.

The required pair of encrypted VLAN Attachments can be created leveraging the [net-vlan-attachment](../net-vlan-attachment/) module.

## Examples

### Single region setup

```hcl
resource "google_compute_router" "encrypted-interconnect-overlay-router" {
  name    = "encrypted-interconnect-overlay-router"
  project = "myproject"
  network = "mynet"
  region  = "europe-west8"
  bgp {
    asn               = 64514
    advertise_mode    = "CUSTOM"
    advertised_groups = ["ALL_SUBNETS"]
    advertised_ip_ranges {
      range = "10.255.255.0/24"
    }
    advertised_ip_ranges {
      range = "192.168.255.0/24"
    }
  }
}

resource "google_compute_external_vpn_gateway" "default" {
  name        = "peer-vpn-gateway"
  project     = "myproject"
  description = "Peer IPSec over Interconnect VPN gateway"
  interface {
    id         = 0
    ip_address = "10.0.0.1"
  }
  interface {
    id         = 1
    ip_address = "10.0.0.2"
  }
}

module "vpngw-a" {
  source     = "./fabric/modules/net-ipsec-over-interconnect"
  project_id = "myproject"
  network    = "mynet"
  region     = "europe-west8"
  name       = "vpngw-a"
  interconnect_attachments = {
    a = "attach-01"
    b = "attach-02"
  }
  peer_gateway_config = {
    create = false
    id     = google_compute_external_vpn_gateway.default.id
  }
  router_config = {
    create = false
    name   = google_compute_router.encrypted-interconnect-overlay-router.name
  }
  tunnels = {
    remote-0 = {
      bgp_peer = {
        address = "169.254.1.2"
        asn     = 64514
        # MD5 Authentication is optional
        md5_authentication_key = {
          name = "foo"
          key  = "bar"
        }
      }
      bgp_session_range     = "169.254.1.1/30"
      shared_secret         = "foobar"
      vpn_gateway_interface = 0
    }
    remote-1 = {
      bgp_peer = {
        address = "169.254.1.6"
        asn     = 64514
      }
      bgp_session_range     = "169.254.1.5/30"
      shared_secret         = "foobar"
      vpn_gateway_interface = 1
    }
    remote-2 = {
      bgp_peer = {
        address = "169.254.1.10"
        asn     = 64514
      }
      bgp_session_range     = "169.254.1.9/30"
      shared_secret         = "foobar"
      vpn_gateway_interface = 0
    }
    remote-3 = {
      bgp_peer = {
        address = "169.254.1.14"
        asn     = 64514
      }
      bgp_session_range     = "169.254.1.13/30"
      shared_secret         = "foobar"
      vpn_gateway_interface = 1
    }
  }
}
# tftest modules=1 resources=16
```
<!-- BEGIN TFDOC -->
## Variables

| name | description | type | required | default |
|---|---|:---:|:---:|:---:|
| [interconnect_attachments](variables.tf#L17) | VLAN attachments used by the VPN Gateway. | <code>object&#40;&#123;&#8230;&#125;&#41;</code> | ✓ |  |
| [name](variables.tf#L25) | Common name to identify the VPN Gateway. | <code>string</code> | ✓ |  |
| [network](variables.tf#L30) | The VPC name to which resources are associated to. | <code>string</code> | ✓ |  |
| [peer_gateway_config](variables.tf#L35) | IP addresses for the external peer gateway. | <code>object&#40;&#123;&#8230;&#125;&#41;</code> | ✓ |  |
| [project_id](variables.tf#L54) | The project id. | <code>string</code> | ✓ |  |
| [region](variables.tf#L59) | GCP Region. | <code>string</code> | ✓ |  |
| [router_config](variables.tf#L64) | Cloud Router configuration for the VPN. If you want to reuse an existing router, set create to false and use name to specify the desired router. | <code>object&#40;&#123;&#8230;&#125;&#41;</code> | ✓ |  |
| [tunnels](variables.tf#L79) | VPN tunnel configurations. | <code>map&#40;object&#40;&#123;&#8230;&#125;&#41;&#41;</code> |  | <code>&#123;&#125;</code> |

## Outputs

| name | description | sensitive |
|---|---|:---:|
| [bgp_peers](outputs.tf#L18) | BGP peer resources. |  |
| [external_gateway](outputs.tf#L25) | External VPN gateway resource. |  |
| [id](outputs.tf#L30) | Fully qualified VPN gateway id. |  |
| [random_secret](outputs.tf#L35) | Generated secret. |  |
| [router](outputs.tf#L40) | Router resource (only if auto-created). |  |
| [router_name](outputs.tf#L45) | Router name. |  |
| [self_link](outputs.tf#L50) | HA VPN gateway self link. |  |
| [tunnels](outputs.tf#L55) | VPN tunnel resources. |  |
<!-- END TFDOC -->
