Files

2020-08-17 12:06:41 -04:00

20 KiB

Raw Blame History

Ansible role `bind`

An Ansible role for setting up BIND ISC as an authoritative-only DNS server for multiple domains. 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 forward and reverse zones, including for IPv6. Although enabling recursion is supported (albeit strongly discouraged), consider using another role if you want to set up a caching or forwarding name server.

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

If you like/use this role, please consider giving it a star and rating it on the role's Ansible Galaxy page. Thanks!

See the change log for notable changes between versions.

Requirements

The package python-ipaddr should be installed on the management node (since v3.7.0)

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_allow_recursion`	`['any']`	Similar to bind_allow_query, this option applies to recursive queries.
`bind_check_names`	`[]`	Check host names for compliance with RFC 952 and RFC 1123 and take the defined action (e.g. `warn`, `ignore`, `fail`).
`bind_dns_keys`	`[]`	A list of binding keys, which are dicts with fields `name` `algorithm` and `secret`. See below for an example.
`bind_dnssec_enable`	`true`	Is DNSSEC enabled
`bind_dnssec_validation`	`true`	Is DNSSEC validation enabled
`bind_extra_include_files`	`[]`
`bind_forward_only`	`false`	If `true`, BIND is set up as a caching name server
`bind_forwarders`	`[]`	A list of name servers to forward DNS requests to.
`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_logs`	-	A list of logging channels to configure, with a separate dict for each domain, with relevant details
`- allow_update`	`['none']`	A list of hosts that are allowed to dynamically update this DNS zone.
`- also_notify`	-	A list of servers that will receive a notification when the master zone file is reloaded.
`- delegate`	`[]`	Zone delegation. See below this table for examples.
`bind_query_log`	-	A dict with fields `file` (e.g. `data/query.log`), `versions`, `size`, when defined this will turn on the query log
`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_statistcs_channels`	`false`	if `true`, BIND is configured with a statistics_channels clause (currently only supports a single inet)
`bind_zone_dir`	-	When defined, sets a custom absolute path to the server directory (for zone files, etc.) instead of the default.
`bind_zone_domains`	n/a	A list of domains to configure, with a separate dict for each domain, with relevant details
`- allow_update`	`['none']`	A list of hosts that are allowed to dynamically update this DNS zone.
`- also_notify`	-	A list of servers that will receive a notification when the master zone file is reloaded.
`- create_forward_zones`	-	When initialized and set to `false`, creation of forward zones will be skipped (resulting in a reverse only zone)
`- create_reverse_zones`	-	When initialized and set to `false`, creation of reverse zones will be skipped (resulting in a forward only zone)
`- delegate`	`[]`	Zone delegation. See below this table for examples.
`- hostmaster_email`	`hostmaster`	The e-mail address of the system administrator for the zone
`- hosts`	`[]`	Host definitions. See below this table for examples.
`- ipv6_networks`	`[]`	A list of the IPv6 networks that are part of the domain, in CIDR notation (e.g. 2001:db8::/48)
`- mail_servers`	`[]`	A list of dicts (with fields `name` and `preference`) specifying the mail servers for this domain.
`- name_servers`	`[ansible_hostname]`	A list of the DNS servers for this domain.
`- name`	`example.com`	The domain name
`- networks`	`['10.0.2']`	A list of the networks that are part of the domain
`- other_name_servers`	`[]`	A list of the DNS servers outside of this domain.
`- services`	`[]`	A list of services to be advertised by SRV records
`- text`	`[]`	A list of dicts with fields `name` and `text`, specifying TXT records. `text` can be a list or string.
`- naptr`	`[]`	A list of dicts with fields `name`, `order`, `pref`, `flags`, `service`, `regex` and `replacement` specifying NAPTR records.
`bind_zone_file_mode`	0640	The file permissions for the main config file (named.conf)
`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_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.

Minimal variables for a working zone

Even though only variable bind_zone_master_server_ip is required for the role to run without errors, this is not sufficient to get a working zone. In order to set up an authoritative name server that is available to clients, you should also at least define the following variables:

Variable	Master	Slave
`bind_zone_domains`	V	V
`- name`	V	V
`- networks`	V	V
`- name_servers`	V	--
`- hosts`	V	--
`bind_listen_ipv4`	V	V
`bind_allow_query`	V	V

Domain definitions

bind_zone_domains:
  - name: mydomain.com           # Domain name
    create_reverse_zones: false  # Skip creation of reverse zones
    hosts:
      - name: pub01
        ip: 192.0.2.1
        ipv6: 2001:db8::1
        aliases:
          - ns
      - name: '@'                # Enables "http://mydomain.com/"
        ip:
          - 192.0.2.2            # Multiple IP addresses for a single host
          - 192.0.2.3            #   results in DNS round robin
        sshfp:                   # Secure shell fingerprint
          - "3 1 1262006f9a45bb36b1aa14f45f354b694b77d7c3"
          - "3 2 e5921564252fe10d2dbafeb243733ed8b1d165b8fa6d5a0e29198e5793f0623b"
        ipv6:
          - 2001:db8::2
          - 2001:db8::3
        aliases:
          - www
      - name: priv01             # This IP is in another subnet, will result in
        ip: 10.0.0.1             #   multiple reverse zones
      - name: mydomain.net.
        aliases:
          - name: sub01
            type: DNAME          # Example of a DNAME alias record
    networks:
      - '192.0.2'
      - '10'
      - '172.16'
    delegate:
      - zone: foo
        dns: 192.0.2.1
    services:
      - name: _ldap._tcp
        weight: 100
        port: 88
        target: dc001
    naptr:                       # Name Authority Pointer record, used for IP
      - name: "sip"              #   telephony
        order: 100
        pref: 10
        flags: "S"
        service: "SIP+D2T"
        regex: "!^.*$!sip:customer-service@example.com!"
        replacement: "_sip._tcp.example.com."

Minimal slave configuration

    bind_listen_ipv4: ['any']
    bind_allow_query: ['any']
    bind_zone_master_server_ip: 192.168.111.222
    bind_zone_domains:
      - name: example.com

Hosts

Host names that this DNS server should resolve can be specified in hosts as a list of dicts with fields name, ip, aliases and sshfp. Aliases can be CNAME (default) or DNAME records.

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.

If you want to specify multiple IP addresses for a host, add entries to bind_zone_hosts with the same name (e.g. priv01 in the code snippet). This results in multiple A/AAAA records for that host and allows 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.

Networks

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 networks (part of bind_zone_domains.name dict), though, or the host will not get a PTR record for reverse lookup:

Remark that only the network part should be specified here! When specifying a class B IP address (e.g. "172.16") in a variable file, it must be quoted. Otherwise, the Yaml parser will interpret it as a float.

Based on the idea and examples detailed at https://linuxmonk.ch/wordpress/index.php/2016/managing-dns-zones-with-ansible/ for the gdnsd package, the zonefiles are fully idempotent, and thus only get updated if "real" content changes.

Zone delgation

To delegate a zone to a DNS, it is enough to create a NS record (under delegate) which is the equivalent of:

foo IN NS 192.0.2.1

Service records

Service (SRV) records can be added with the services. This should be 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.

Binding Keys

Binding keys can be defined like this:

bind_dns_keys:
  - name: master_key
    algorithm: hmac-sha256
    secret: "azertyAZERTY123456"
bind_extra_include_files:
  - "{{ bind_auth_file }}"

tip: Extra include file must be set as an ansible variable because file is OS dependant

This will be set in a file "{{ bind_auth_file }} (e.g. /etc/bind/auth_transfer.conf for debian) which have to be added in the list variable bind_extra_include_files

Dependencies

No dependencies.

Example Playbook

See the test playbook converge.yml for an elaborate example that showcases most features.

Testing

This role is tested using Ansible Molecule. Tests are launched automatically on Travis CI after each commit and PR.

This Molecule configuration will:

Run Yamllint and Ansible Lint
Create two Docker containers, one primary (ns1) and one secondary (ns2) DNS server
Run a syntax check
Apply the role with a test playbook
Run acceptance tests with BATS

This process is repeated for the supported Linux distributions.

Local test environment

If you want to set up a local test environment, you can use this reproducible setup based on Vagrant+VirtualBox: https://github.com/bertvv/ansible-testenv. Steps to install the necessary tools manually:

Docker and BATS should be installed on your machine (assumed to run Linux). No Docker containers should be running when you start the test.
As recommended by Molecule, create a python virtual environment
Install the software tools python3 -m pip install molecule docker netaddr yamllint ansible-lint
Navigate to the root of the role directory and run molecule test

Molecule automatically deletes the containers after a test. If you would like to check out the containers yourself, run molecule converge followed by molecule login --host HOSTNAME.

The Docker containers are based on images created by Jeff Geerling, specifically for Ansible testing (look for images named geerlingguy/docker-DISTRO-ansible). You can use any of his images, but only the distributions mentioned in meta/main.yml are supported.

The default config will start two Centos 7 containers (the primary supported platform at this time). Choose another distro by setting the MOLECULE_DISTRO variable with the command, e.g.:

MOLECULE_DISTRO=debian9 molecule test

MOLECULE_DISTRO=debian9 molecule converge

You can run the acceptance tests on both servers with molecule verify or manually with

SUT_IP=172.17.0.2 bats molecule/default/files/dns.bats

You need to initialise the variable SUT_IP, the system under test's IP address. The primary server, ns1, should have IP address 172.17.0.2 and the secondary server, ns2 172.17.0.3.

License

BSD

Contributors

This role could only have been realized thanks to the contributions of many. If you have an idea to improve it even further, don't hesitate to pitch in!

Issues, feature requests, ideas, suggestions, etc. can be posted in the Issues section.

Pull requests are also very welcome. Please create a topic branch for your proposed changes. If you don't, this will create conflicts in your fork after the merge. Don't hesitate to add yourself to the contributor list below in your PR!

Maintainers:

Contributors:

20 KiB Raw Blame History

Ansible role bind