peterjanes / ansible-role-bind

Sets up ISC BIND on RHEL/CentOS 6/7 as an authoritative DNS server for a single domain (master and/or slave).

Ansible role bind

An Ansible role for setting up BIND ISC as an authoritative DNS server for a single domain. Specifically, the responsibilities of this role are to:

• install BIND
• set up the main configuration file
  • master server
  • slave server
• set up forward and reverse lookup zone files

This role supports multiple reverse zones. Forward IPv6 lookups are also supported. Reverse IPv6 lookups, as of yet, are not (See Issue #10).

Configuring the firewall is not a concern of this role, so you should do this using another role (e.g. bertvv.el7).

If you like/use this role, please consider giving it a star or reviewing it on Ansible Galaxy. Thanks!

Requirements

• This role is written specifically for RHEL/CentOS and works on versions 6 and 7.
• The filter_plugins directory should be copied to ${ANSIBLE_HOME}. It contains a few functions that manipulate IP addresses. If you forget this step, you will get the error message "no filter named 'reverse_lookup_zone'" in the task 'Main BIND config file'. See Issue #5.

Role Variables

Variables are not required, unless specified.

Variable	Default	Comments (type)
bind_acls	[]	A list of ACL definitions, which are dicts with fields name and match_list. See below for an example.
bind_allow_query	['localhost']	A list of hosts that are allowed to query this DNS server. Set to ['any'] to allow all hosts
bind_listen_ipv4	['127.0.0.1']	A list of the IPv4 address of the network interface(s) to listen on. Set to ['any'] to listen on all interfaces.
bind_listen_ipv6	['::1']	A list of the IPv6 address of the network interface(s) to listen on
bind_log	data/named.run	Path to the log file
bind_other_name_servers	[]	A list of nameservers outside of the domain. For each one, an NS record will be created.
bind_recursion	false	Determines whether requests for which the DNS server is not authoritative should be forwarded†.
bind_rrset_order	random	Defines order for DNS round robin (either random or cyclic)
bind_zone_also_notify	-	A list of servers that will receive a notification when the master zone file is reloaded.
bind_zone_hostmaster_email	hostmaster	The e-mail address of the system administrator
bind_zone_hosts	[]	Host definitions. See below this table for examples.
bind_zone_mail_servers	[{name: mail, preference: 10}]	A list of dicts (with fields name and preference) specifying the mail servers for this domain.
bind_zone_master_server_ip	-	(Required) The IP address of the master DNS server.
bind_zone_minimum_ttl	1D	Minimum TTL field in the SOA record.
bind_zone_name_servers	[ansible_hostname]	A list of the DNS servers for this domain.
bind_zone_name	example.com	The domain name
bind_zone_networks	['10.0.2']	A list of the networks that are part of the domain
bind_zone_other_name_servers	[]	A list of the DNS servers outside of this domain.
bind_zone_services	[]	A list of services to be advertized by SRV records
bind_zone_text	[]	A list of dicts with fields name and text, specifying TXT records
bind_zone_time_to_expire	1W	Time to expire field in the SOA record.
bind_zone_time_to_refresh	1D	Time to refresh field in the SOA record.
bind_zone_time_to_retry	1H	Time to retry field in the SOA record.
bind_zone_ttl	1W	Time to Live field in the SOA record.

† Best practice for an authoritative name server is to leave recursion turned off. However, for some cases it may be necessary to have recursion turned on.

Host definitions

Host names that this DNS server should resolve can be specified with the variable bind_zone_hosts as a list of dicts with fields name, ip and aliases, e.g.:

bind_zone_hosts:
  - name: pub01
    ip: 192.0.2.1
    ipv6: 2001:db8::1
    aliases:
      - ns
  - name: '@'
    ip:
      - 192.0.2.2
      - 192.0.2.3
    ipv6:
      - 2001:db8::2
      - 2001:db8::3
    aliases:
      - www
  - name: priv01
    ip: 10.0.0.1

To allow to surf to http://example.com/, set the host name of your web server to '@' (must be quoted!). In BIND syntax, @ indicates the domain name itself.

IP addresses (both IPv4 and IPv6) can be specified as a string or as a list. This results in a single or multiple A/AAAA records for the host, respectively. This enables DNS round robin, a simple load balancing technique. The order in which the IP addresses are returned can be configured with role variable bind_rrset_order.

As you can see, not all hosts are in the same network. This is perfectly acceptable, and supported by this role. All networks should be specified in bind_zone_networks, though, or the host will not get a PTR record for reverse lookup:

bind_zone_networks:
  - 192.0.2
  - 10

Remark that only the network part should be specified here!

Service records

Service (SRV) records can be added with the variable bind_zone_services, e.g.:

bind_zone_services:
  - name: _ldap._tcp
    weight: 100
    port: 88
    target: dc001

This is a list of dicts with mandatory fields name (service name), target (host providing the service), port (TCP/UDP port of the service) and optional fields priority (default = 0) and weight (default = 0).

ACLs

ACLs can be defined like this:

bind_acls:
  - name: acl1
    match_list:
      - 192.0.2.0/24
      - 10.0.0.0/8

The names of the ACLs will be added to the allow-transfer clause in global options.

Dependencies

No dependencies. If you want to configure the firewall, do this through another role (e.g. bertvv.el7).

Example Playbook

See the test playbook test.yml (in the tests branch) for an elaborate example that shows all features.

Testing

Setting up the test environment

Tests for this role are provided in the form of a Vagrant environment that is kept in a separate branch, tests. I use git-worktree(1) to include the test code into the working directory. Instructions for running the tests:

1. Fetch the tests branch: git fetch origin tests
2. Create a Git worktree for the test code: git worktree add tests tests (remark: this requires at least Git v2.5.0). This will create a directory tests/.
3. cd tests/
4. vagrant up will then create a VM and apply a test playbook (test.yml).

You may want to change the base box into one that you like. The current one, bertvv/centos71 was generated using a Packer template from the Boxcutter project with a few modifications.

Tests for the bind role

The command vagrant up results in a setup with two DNS servers, a master and a slave, set up according to playbook test.yml.

Hostname	ip
testbindmaster	192.168.56.53
testbindslave	192.168.56.54

IP addresses are in the subnet of the default VirtualBox Host Only network interface (192.168.56.0/24). You should be able to query the servers from your host system. For example, to verify if the slave is updated correctly, you can do the following:

$ dig @192.168.56.54 ns1.example.com +short
testbindmaster.example.com.
192.168.56.53
$ dig @192.168.56.54 example.com www.example.com +short
web.example.com.
192.168.56.20
192.168.56.21
$ dig @192.168.56.54 MX example.com +short
10 mail.example.com.

An automated acceptance test written in BATS is provided that checks most settings specified in tests/test.yml. You can run it by executing the shell script tests/runtests.sh. The script can be run on either your host system (assuming you have a Bash shell), or one of the VMs. The script will download BATS if needed and run the test script tests/dns.bats on both the master and the slave DNS server.

$ cd tests
$ vagrant up
[...]
$ ./runtests.sh
Testing 192.168.56.53
✓ The `dig` command should be installed
✓ It should return the NS record(s)
✓ It should be able to resolve host names
✓ It should be able to resolve IPv6 addresses
✓ It should be able to do reverse lookups
✓ It should be able to resolve aliases
✓ It should return the MX record(s)

6 tests, 0 failures
Testing 192.168.56.54
✓ The `dig` command should be installed
✓ It should return the NS record(s)
✓ It should be able to resolve host names
✓ It should be able to resolve IPv6 addresses
✓ It should be able to do reverse lookups
✓ It should be able to resolve aliases
✓ It should return the MX record(s)

6 tests, 0 failures

Running from the VM:

$ vagrant ssh testbindmaster
Last login: Sun Jun 14 18:52:35 2015 from 10.0.2.2
Welcome to your Packer-built virtual machine.
[vagrant@testbindmaster ~]$ /vagrant/runtests.sh
Testing 192.168.56.53
 ✓ The `dig` command should be installed
[...]

Symbolic links in test code

The directory tests/roles/bind is a symbolic link that should point to the root of this project in order to work. Additionally, the filter_plugins should be linked to the tests directory. To create these links if necessary, do

$ cd tests/
$ mkdir roles
$ ln -frs ../../PROJECT_DIR roles/bind
$ ln -frs ../filter_plugins/ .

Contributing

License

BSD

Contributors

Issues, feature requests, ideas, suggestions, etc. are appreciated and can be posted in the Issues section. Pull requests are also very welcome. Preferably, create a topic branch and when submitting, squash your commits into one (with a descriptive message).

• Bert Van Vreckem (Maintainer)
• Joanna Delaporte