Introduction

awsautodns is a tool that allows an AWS EC2 Instance to automatically register it's IP address in a Route53 Hosted Zone at startup. The install script creates a oneshot service, awsautodns.service, and sets it to start at boot, by installing it to multi-user.target.

awsautodns is useful for avoiding fees associated with using an elastic IP address.

Compatibility

awsautodns has been tested to work on both ARM64 and x86-64 on the following Linux distros:

• Amazon Linux 2
• Ubuntu Server 16/18/20.04 LTS
• Red Hat Enterprise Linux 8

Dependencies

awsautodns has several dependencies for installation.

• net-tools
• aws-cli
• gcc
• make
• git

Once installed, awsautodns has only 2 dependencies.

• net-tools
• aws-cli

Configuration

awsautodns configures itself by reading tags associated with the instance. The available configuration tags are as follows:

• autodnsdomain (Required) - The full domain name to point to. (ex. dev.example.com)
• autodnshostedzoneid (Required) - The Hosted Zone ID (ex. Z119WBBTVP5WFX)

awsautodns uses aws-cli to interact with AWS. It is best practice to create an AMI User for the tool to use with only the required permissions (make sure to save the access key). The required permissions are as follows:

{
	"Effect": "Allow",
	"Action": [
		"ec2:DescribeInstances",
                "ec2:DescribeTags"
	],
	"Resource": "*"
},
{
	"Effect": "Allow",
	"Action": "route53:ChangeResourceRecordSets",
	"Resource": "arn:aws:route53:::hostedzone/YOURHOSTEDZONEIDHERE"
}

Installation

Install all dependencies.

• Ubuntu (net-tools, aws-cli, gcc, make, git):

  sudo apt -y update && sudo apt -y install net-tools && sudo apt -y install gcc && sudo apt -y install make && sudo apt -y install git

  If aws-cli is not already installed, install it.

  • If installing on an ARM64 system, replace "x86_64" with "aarch64".

   sudo apt -y install unzip
   curl "https://awscli.amazonaws.com/awscli-exe-linux-x86_64.zip" -o "awscliv2.zip"
   unzip awscliv2.zip
   rm awscliv2.zip
   sudo ./aws/install
   rm -rf aws/
  

• Amazon Linux 2/RHEL (net-tools, aws-cli, gcc, make, git):

  sudo yum -y update && sudo yum -y install net-tools && sudo yum -y install gcc && sudo yum -y install make && sudo yum -y install git

  If aws-cli is not already installed, install it.

  • If installing on an ARM64 system, replace "x86_64" with "aarch64".

   sudo yum -y install unzip
   curl "https://awscli.amazonaws.com/awscli-exe-linux-x86_64.zip" -o "awscliv2.zip"
   unzip awscliv2.zip
   rm awscliv2.zip
   sudo ./aws/install -b /usr/sbin
   rm -rf aws/
  

If you haven't already done so, configure aws-cli as root.

• The Default output format must be set to json

sudo su
aws configure && exit

Clone this repo.

sudo git clone https://github.com/walia6/awsautodns.git

Run the install bash file. Note: In RHEL, the install script must set SELINUX=disabled, due to a bug with SELinux. This has security implications.

sudo bash awsautodns/install.sh

Uninstallation

Uninstalling awsautodns is simple.

sudo systemctl stop awsautodns && sudo systemctl disable awsautodns
sudo rm -f /etc/systemd/system/awsautodns.service
sudo rm -rf /opt/awsautodns

If you wish to also remove the log file,

sudo rm -f /var/log/awsautodns.log.