DynamicDNS

DynamicDNS is tool that queries your public IPv4 address periodically, and updates a specific A record in Amazon Route53 if this IP address changes.

This gem is useful as a command-line executable, and as a library.

Usage

The following usage examples will configure the daemon to run every 10 minutes, updating the hosted zone for foo.com in Route53 to have an A record that points ssh.foo.com to the computer's public IPv4 address. See the Configuration section below for more information on the environment variables used to configure the daemon.

Ensure you have installed this gem to use the command-line tool. You must have Ruby 2.4, or greater, installed.

$ gem install dynamic_dns

Command-line

# use environment variables to configure the daemon
# exit with Ctrl+c
$ DYNAMIC_DNS_DOMAIN=foo.com DYNAMIC_DNS_SUBDOMAIN=ssh DYNAMIC_DNS_INTERVAL=600 dynamic-dns

`systemd` Start-up Script

If you are using rvm with systemd, ensure that rvm was installed using sudo, then install this gem.

[Unit]
Description=DynamicDNS daemon

[Service]
Type=simple
Environment="GEM_HOME=/usr/local/rvm/gems/ruby-2.4.1"
Environment="GEM_PATH=/usr/local/rvm/gems/ruby-2.4.1:/usr/local/rvm/gems/ruby-2.4.1@global"
Environment="PATH=/usr/local/rvm/gems/ruby-2.4.1/bin:/usr/local/rvm/gems/ruby-2.4.1@global/bin:/usr/local/rvm/rubies/ruby-2.4.1/bin:$PATH"
Environment="AWS_ACCESS_KEY_ID=[REDACTED]"
Environment="AWS_SECRET_ACCESS_KEY=[REDACTED]"
Environment="DYNAMIC_DNS_DOMAIN=foo.com"
Environment="DYNAMIC_DNS_SUBDOMAIN=ssh"
Environment="DYNAMIC_DNS_INTERVAL=600"
ExecStart=/usr/local/rvm/gems/ruby-2.4.1/bin/dynamic-dns

[Install]
WantedBy=multi-user.target

Ruby

require 'dynamic-dns'

daemon = DynamicDns::Daemon.new "foo.com", "ssh", 600
daemon.start # runs the daemon and blocks the thread

Confirguation

It is possible to configure this daemon using environment variables.

Variable	Required?	Default	Example	Description
`DYNAMIC_DNS_DOMAIN`	Y	N/A	`foo.com`	This domain's hosted zone will be updated. It must already have an existing hosted zone in Route53 prior to running the daemon.
`DYNAMIC_DNS_SUBDOMAIN`	Y	N/A	`ssh`	The name of the A record that will point to the public IP address discovered by the daemon.
`DYNAMIC_DNS_INTERVAL`	N	`60`	`60`	The interval in seconds that the daemon should query for the public IPv4 address.
`AWS_ACCESS_KEY_ID`	Y	N/A	`abc123`	Your AWS access key ID. It must have permissions to manage Route53. This requirement is defined by the `aws-sdk` gem (link). An alternative method to providnig your AWS credentials is to create an `~/.aws/credentials` file.
`AWS_SECRET_ACCESS_KEY`	Y	N/A	`abc123`	Your AWS secret access key. See above for notes on AWS credentials.

Author

Dhruv Dang
hi@dhruv.io
dhruv.io

dynamic_dns

Runtime