# Containerized on-premises infrastructure

This module manages a `cloud-config` configuration that starts an emulated on-premises infrastructure running in Docker Compose on a single instance, and connects it via static or dynamic VPN to a Google Cloud VPN gateway.

The emulated on-premises infrastructure is composed of:

- a [Strongswan container](./docker-images/strongswan) managing the VPN tunnel to GCP
- an optional Bird container managing the BGP session
- a CoreDNS container servng local DNS and forwarding to GCP
- an Nginx container serving a simple static web page
- a [generic Linux container](./docker-images/toolbox) used as a jump host inside the on-premises network

A [complete scenario using this module](../../../infrastructure/onprem-google-access-dns) is available in the infrastructure examples.

The module renders the generated cloud config in the `cloud_config` output, to be used in instances or instance templates via the `user-data` metadata.

For convenience during development or for simple use cases, the module can optionally manage a single instance via the `test_instance` variable. If the instance is not needed the `instance*tf` files can be safely removed. Refer to the [top-level README](../README.md) for more details on the included instance.

## Examples

### Static VPN

The test instance is optional, as described above.

```hcl
module "cloud-vpn" {
  source     = "./modules/net-vpn-static"
  project_id = "my-project"
  region     = "europe-west1"
  network    = "my-vpc"
  name       = "to-on-prem"
  remote_ranges = ["192.168.192.0/24"]
  tunnels = {
    remote-0 = {
      ike_version       = 2
      peer_ip           = module.on-prem.external_address
      shared_secret     = ""
      traffic_selectors = { local = ["0.0.0.0/0"], remote = null }
    }
  }
}

module "on-prem" {
  source = "./modules/cos-container/on-prem"
  name       = "onprem"
  vpn_config = {
    type          = "static"
    peer_ip       = module.cloud-vpn.address
    shared_secret = module.cloud-vpn.random_secret
  }
  test_instance = {
    project_id = "my-project"
    zone       = "europe-west1-b"
    name       = "cos-coredns"
    type       = "f1-micro"
    network    = "default"
    subnetwork = "https://www.googleapis.com/compute/v1/projects/my-project/regions/europe-west1/subnetworks/my-subnet"
  }
}
```

<!-- BEGIN TFDOC -->
## Variables

| name | description | type | required | default |
|---|---|:---: |:---:|:---:|
| vpn_config | VPN configuration, type must be one of 'dynamic' or 'static'. | <code title="object&#40;&#123;&#10;peer_ip       &#61; string&#10;shared_secret &#61; string&#10;type &#61; string&#10;&#125;&#41;">object({...})</code> | ✓ |  |
| *config_variables* | Additional variables used to render the cloud-config and CoreDNS templates. | <code title="map&#40;any&#41;">map(any)</code> |  | <code title="">{}</code> |
| *coredns_config* | CoreDNS configuration path, if null default will be used. | <code title="">string</code> |  | <code title="">null</code> |
| *local_ip_cidr_range* | IP CIDR range used for the Docker onprem network. | <code title="">string</code> |  | <code title="">192.168.192.0/24</code> |
| *test_instance* | Test/development instance attributes, leave null to skip creation. | <code title="object&#40;&#123;&#10;project_id &#61; string&#10;zone       &#61; string&#10;name       &#61; string&#10;type &#61; string&#10;network    &#61; string&#10;subnetwork &#61; string&#10;&#125;&#41;">object({...})</code> |  | <code title="">null</code> |
| *test_instance_defaults* | Test/development instance defaults used for optional configuration. If image is null, COS stable will be used. | <code title="object&#40;&#123;&#10;disks &#61; map&#40;object&#40;&#123;&#10;read_only &#61; bool&#10;size      &#61; number&#10;&#125;&#41;&#41;&#10;image                 &#61; string&#10;metadata              &#61; map&#40;string&#41;&#10;nat                   &#61; bool&#10;service_account_roles &#61; list&#40;string&#41;&#10;tags                  &#61; list&#40;string&#41;&#10;&#125;&#41;">object({...})</code> |  | <code title="&#123;&#10;disks    &#61; &#123;&#125;&#10;image    &#61; null&#10;metadata &#61; &#123;&#125;&#10;nat      &#61; false&#10;service_account_roles &#61; &#91;&#10;&#34;roles&#47;logging.logWriter&#34;,&#10;&#34;roles&#47;monitoring.metricWriter&#34;&#10;&#93;&#10;tags &#61; &#91;&#34;ssh&#34;&#93;&#10;&#125;">...</code> |
| *vpn_dynamic_config* | BGP configuration for dynamic VPN, ignored if VPN type is 'static'. | <code title="object&#40;&#123;&#10;local_bgp_asn     &#61; number&#10;local_bgp_address &#61; string&#10;peer_bgp_asn      &#61; number&#10;peer_bgp_address  &#61; string&#10;&#125;&#41;">object({...})</code> |  | <code title="&#123;&#10;local_bgp_asn     &#61; 65002&#10;local_bgp_address &#61; &#34;169.254.0.2&#34;&#10;peer_bgp_asn      &#61; 65001&#10;peer_bgp_address  &#61; &#34;169.254.0.1&#34;&#10;&#125;">...</code> |
| *vpn_static_ranges* | Remote CIDR ranges for static VPN, ignored if VPN type is 'dynamic'. | <code title="list&#40;string&#41;">list(string)</code> |  | <code title="">["10.0.0.0/8"]</code> |

## Outputs

| name | description | sensitive |
|---|---|:---:|
| cloud_config | Rendered cloud-config file to be passed as user-data instance metadata. |  |
| test_instance | Optional test instance name and address |  |
<!-- END TFDOC -->
