DNS role
========

This role facilitates the configuration of the domain name service (DNS). This role is abstracted for Dell EMC platforms running OS9 and requires an SSH connection for connectivity to a Dell EMC Networking device. You can use any of the built-in OS connection variables.

Role variables
--------------

- Role is abstracted using the *ansible_network_os* variable that can take the dellemc.os9.os9 as a value
- If *os9_cfg_generate* set to true, the variable generates the role configuration commands in a file
- Any role variable with a corresponding state variable set to absent negates the configuration of that variable
- Setting an empty value for any variable negates the corresponding configuration
- Variables and values are case-sensitive

**os9_dns keys**

| Key        | Type                      | Description                                             | Support               |
|------------|---------------------------|---------------------------------------------------------|-----------------------|
| ``name_server`` | list | Configures DNS (see ``name_server.*``) | os9 |
| ``name_server.domain_lookup`` | boolean | Enables or disables domain name lookup   | os9 |
| ``name_server.ip`` | list | Configures the name server IP | os9 |
| ``name_server.vrf`` | list | Configures VRF for each IP | os9 |
| ``name_server.state`` | string: absent,present\* | Deletes the name server IP if set to absent | os9 |

> **NOTE**: Asterisk (\*) denotes the default value if none is specified. 

Connection variables
--------------------

Ansible Dell EMC Networking roles require connection information to establish communication with the nodes in your inventory. This information can exist in the Ansible *group_vars* or *host_vars* directories or inventory, or in the playbook itself.

| Key         | Required | Choices    | Description                                         |
|-------------|----------|------------|-----------------------------------------------------|
| ``ansible_host`` | yes      |            | Specifies the hostname or address for connecting to the remote device over the specified transport |
| ``ansible_port`` | no       |            | Specifies the port used to build the connection to the remote device; if value is unspecified, the ANSIBLE_REMOTE_PORT option is used; it defaults to 22 |
| ``ansible_ssh_user`` | no       |            | Specifies the username that authenticates the CLI login for the connection to the remote device; if value is unspecified, the ANSIBLE_REMOTE_USER environment variable value is used  |
| ``ansible_ssh_pass`` | no       |            | Specifies the password that authenticates the connection to the remote device.  |
| ``ansible_become`` | no       | yes, no\*   | Instructs the module to enter privileged mode on the remote device before sending any commands; if value is unspecified, the ANSIBLE_BECOME environment variable value is used, and the device attempts to execute all commands in non-privileged mode |
| ``ansible_become_method`` | no       | enable, sudo\*   | Instructs the module to allow the become method to be specified for handling privilege escalation; if value is unspecified, the ANSIBLE_BECOME_METHOD environment variable value is used. |
| ``ansible_become_pass`` | no       |            | Specifies the password to use if required to enter privileged mode on the remote device; if ``ansible_become`` is set to no this key is not applicable. |
| ``ansible_network_os`` | yes      | os9, null\*  | This value is used to load the correct terminal and cliconf plugins to communicate with the remote device. |

> **NOTE**: Asterisk (\*) denotes the default value if none is specified.

Dependencies
------------

The *os9_dns* role is built on modules included in the core Ansible code. These modules were added in Ansible version 2.2.0.

Example playbook
----------------

This example uses the *os9_dns* role to completely set up the DNS server configuration. The example creates a *hosts* file with the switch details and corresponding variables. The hosts file should define the *ansible_network_os* variable with corresponding Dell EMC networking OS name.

When *os9_cfg_generate* is set to true, generates the configuration commands as a .part file in *build_dir* path. By default it is set to false. It writes a simple playbook that only references the *os9_dns* role. By including the role, you automatically get access to all of the tasks to configure DNS.

**Sample hosts file**

    leaf1 ansible_host= <ip_address> 

**Sample host_vars/leaf1**

    hostname: leaf1
    ansible_become: yes
    ansible_become_method: xxxxx
    ansible_become_pass: xxxxx
    ansible_ssh_user: xxxxx
    ansible_ssh_pass: xxxxx
    ansible_network_os: dellemc.os9.os9
    build_dir: ../temp/os9	  
	os9_dns:
	   domain_lookup: true
	   name_server:
		 - ip:
			- 1.1.1.1
			- 1.1.1.2
		   vrf:
			- test
			- management
		   state: absent
		 - ip:
			- 2.2.2.2
		 - ip:
			- 3.3.2.2
		   state: absent

**Simple playbook to setup DNS - leaf.yaml**

    - hosts: leaf1
      roles:
         - dellemc.os9.os9_dns

**Run**

    ansible-playbook -i hosts leaf.yaml

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