`nbde_server`
======================
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Ansible role for configuring Network-Bound Disk Encryption servers (e.g. tang).

This role currently supports `tang` as a provider and it can set up tang servers.

Supported Distributions
-----------------------
* RHEL-7+, CentOS-7+
* Fedora

Limitations
-----------

It is not currently possible to specify a custom port for the NBDE servers configured by this role.


Role Variables
--------------

These are the variables that can be passed to the role:

| **Variable** | **Default** | **Description** |
|----------|-------------|------|
| `nbde_server_provider` | `tang` | identifies the provider for `nbde_server` role. We currently support `tang` as an `nbde_server` provider, meaning that the `nbde_server` role is currently able to provision/deploy tang servers.
| `nbde_server_service_state` | `started` | indicates the state the nbde_server should be. It can be either `started` (default) or `stopped`. `started` means the server is accepting connections, whereas `stopped` means it is not accepting connections.
| `nbde_server_rotate_keys`| `no` | indicates whether we should rotate existing keys -- if any -- , then create new keys. Default behavior (`no`) is to create new keys, if there are none, and don't touch the keys, if they exist. If set to `yes`, existing keys will be rotated and new keys will be created.
|`nbde_server_fetch_keys`| `no` | indicates whether we should fetch keys to the control node, in which case they will be placed in `nbde_server_keys_dir`. You **must** set `nbde_server_keys_dir` to use `nbde_server_fetch_keys`.
|`nbde_server_deploy_keys`| `no` |indicates whether we should deploy the keys located in `nbde_server_keys_dir` directory to the remote hosts. You **must** set `nbde_server_keys_dir` to use `nbde_server_deploy_keys`.
|`nbde_server_keys_dir`| | specifies a directory in the control node that contains keys to be deployed to the remote hosts. Keys located in the top level directory will be deployed to every remote host, while keys located within subdirectories named after the remote hosts  -- as per the inventory -- will be deployed only to these specific hosts. `nbde_server_keys_dir` **must** be an absolute path. You need to set this to use either `nbde_server_fetch_keys` and/or `nbde_server_deploy_keys`.


#### nbde_server_fetch_keys and nbde_server_deploy_keys
To use either of these options, you need to specify `nbde_server_keys_dir`, a directory, with an absolute path.

The behavior of using these variables is described next:

#####  When `nbde_server_fetch_keys` is set to `yes`, the role will fetch keys from the hosts in the following manner:
- if `nbde_server_deploy_keys` is not set, the keys from every host will be fetched and placed in directories named after the host,
  inside `nbde_server_keys_dir`
- if `nbde_server_deploy_keys` is set, only the keys from the first host in the inventory will be fetched, and it will be placed in
  the top level directory of `nbde_server_keys_dir`


#####  `nbde_server_deploy_keys` is simple: if it is set to yes, it will deploy the keys available in `nbde_server_keys_dir`, in the following manner:
- the keys located in the top level directory of `nbde_server_keys_dir` will be deployed to every host
- the keys located within subdirectories named after hosts in the inventory, inside `nbde_server_keys_dir`, will be deployed to that
  specific host


Example Playbooks
-----------------

#### Example 1: deploy NBDE server to every host in the inventory
```yaml
---
- hosts: all

  roles:
    - fedora.linux_system_roles.nbde_server
```

#### Example 2: lift the keys from every NBDE server install in `/root/nbde_server/keys`
```yaml
---
- hosts: all

  vars:
    nbde_server_fetch_keys: yes
    nbde_server_keys_dir: /root/nbde_server/keys

  roles:
    - fedora.linux_system_roles.nbde_server
```

After this, you can backup your keys, which will be placed in `/root/nbde_server/keys`, within subdirectories named after the host they belong to.

#### Example 3: redeploy keys from a backup taken with Example 2:

To redeploy keys, they must be placed into subdirectories named after the host they are to be deployed to. With `/root/nbde_server/keys` after Example 2, use the following playbook to redeploy the same keys to the same hosts:

```yaml
---
- hosts: all

  vars:
    nbde_server_deploy_keys: yes
    nbde_server_keys_dir: /root/nbde_server/keys

  roles:
    - fedora.linux_system_roles.nbde_server
```

#### Example 4: deploy an NBDE server and use the same keys in every host
**NOTE** This is not recommended, but it is supported
```yaml
---
- hosts: all

  vars:
    nbde_server_fetch_keys: yes
    nbde_server_deploy_keys: yes
    nbde_server_keys_dir: /root/nbde_server/keys

  roles:
    - fedora.linux_system_roles.nbde_server
```

License
-------

MIT
