ansible-role-localdns

An Ansible role to install bind9 & isc-dhcp-server on the target hosts.

Summary

This Ansible role installs bind9 and isc-dhcp-server on the target host. It allows to create a local network and assign IPs to hosts based on their mac address. This role does not cover all possible configurations and edge cases of a DNS and/or DHCP server but instead was created to cover my specific requirements in my test lab. This includes a fixed 10.0.0.0/16 network in the bind configuration files and some other things like network ranges, subnet masks and router IPs. Nevertheless I hope it is of any use to some people out there.

It has been tested with the following Linux distributions.

• Debian 9

More Linux distributions will follow soon.

Dependencies

• Ansible >= 2.x
• aptitude (Ansible < 2.4)

Installation

To use this role it must first get downloaded from Ansible Galaxy. To install the role execute the command below on your Ansible controle machine. For more information please refer to the official documentation.

ansible-galaxy install frieder.localdns

The command above will always pull the latest version off of Galaxy. Another possibility is to pull the role from Github and define a specific release version to download. This allows for better control over which version of this role to be used. Create a requirements.yml and put the following content in it.

---
- name: frieder.localdns
  src: https://github.com/frieder/ansible-role-localdns
  version: 1.0.0

Next you can execute ansible-galaxy install -r ./requirements.yml --ignore-errors and it will download all dependencies defined in this list. --ignore-errors will make sure that the whole list is processed even when some dependencies are already downloaded. A nice overview of possible entries for requirements.yml can be found here.

Role Variables

Variable	Default	Description
localdns_domain		Defines the domain name of the local network - e.g. domain.local
localdns_subnet	255.255.255.0	The subnet of the network.
localdns_dns		The DNS servers of the network. For multiple DNS servers provide a comma separated list of IPs - e. g. 10.0.1.10,10.0.1.20
localdns_ntp		The NTP servers of the network. For multiple NTP servers provide a comma separated list of IPs.
localdns_dhcp_lease_def	600	The default DHCP lease time in seconds.
localdns_dhcp_lease_max	7200	The maximum DHCP lease time in seconds.
localdns_dhcp_ipforwarding	'on'	Define whether IP forwarding will be allowed or not. Useful if different subnets are in use.
localdns_zones		A list of one or more zones. For an overview of the fields of a zone please check below.

Zone

Each zone defines a subnet and has the possibility to define the following fields to overwrite the default variables mentioned above.

Field	Required	Description
router	1	Define the IP of the zone router.
subnet	?	Define a different subnet mask than the mask in the network settings.
dns	?	Define a different set of DNS servers for this zone.
ntp	?	Define a different set of NTP servers for this zone.
ipforwarding	?	Define whether IP forwarding is enabled for this zone or not.
entries/entry	+	For an overview of the possible fields of an entry please check below.

Entry

Each zone can have multiple entries. Each entry defines the hostname, it's assigned IP address and the mac address of the network interface.

Field	Description
host	The hostname
ip	The IP that should get assigned to the host
mac	The mac address that belongs to this host and ip

Example Playbooks

A simple network with three zones

- hosts: dns
  roles:
  - role: frieder.localdns
    localdns_domain: example.local
    localdns_subnet: 255.255.0.0
    localdns_dns: 10.0.0.3,10.0.1.2,10.0.2.2
    localdns_ntp: '{{ localdns_dns }}'
    localdns_dhcp_lease_def: 600
    localdns_dhcp_lease_max: 7200
    localdns_dhcp_ipforwarding: 'on'
    localdns_zones:
    - zone:
      router: 10.0.0.1
      entries:
      - entry:
        host: 'test1'
        ip: 10.0.0.10
        mac: 'B6:D5:87:4F:1C:32'
    - zone:
      router: 10.0.1.1
      entries:
      - entry:
        host: 'test2'
        ip: 10.0.1.10
        mac: 'A6:C9:79:F2:61:FE'
    - zone:
      router: 10.0.2.1
      subnet: 255.255.255.0
      dns: 10.0.2.2
      ntp: 10.0.2.2
      ipforwarding: 'off'
      entries:
      - entry:
        host: 'test3'
        ip: 10.0.2.10
        mac: '3E:DE:0E:12:F4:E2'

Example Output

The files getting created by aboves playbook are available here.