DIY Dynamic DNS on Google Cloud Functions

DIYDynDNS is a simple api endpoint that listens for HTTPs requests, extracts the IP address of the caller (via X-Forwarded-For header) and updates the specified A entry to point to that IP address.

Whole purpose of this mini-project is to overcome the dynamic ip allocation by most ISPs.

⚠️ Make sure that the API key is safely stored, otherwise anyone would be able to update your DNS records!

Getting Started

Prerequisites

• Google Cloud project/account
• gcloud cli
• Terraform

Deploying

Before anything, make sure you are authenticated to Google Cloud Platform:

1. Run gcloud auth login and gcloud auth application-default login.
2. Enable necessary APIS:

gcloud services enable cloudbuild.googleapis.com \
cloudfunctions.googleapis.com \
run.googleapis.com \
dns.googleapis.com

Deploying

1. Navigate to terraform folder.
2. Customize terraform.tfvars based on terraform.tfvars.template.
3. Run: terraform init, terraform plan, terraform apply
4. Check the output to get the URL for your newly deployed service or get it via the following command: gcloud run services list | grep -i diydns-function

Deploying changes

In case you made some customization to the code, you can easily push the changes with gcloud (from project's root folder):

export REGION=REGION_YOU_SET_IN_TERRAFORM_TFVARS

gcloud functions deploy diydns-function \
  --gen2 \
  --region=${REGION} \
  --runtime=go122 \
  --source=. \
  --entry-point=handleHTTP \
  --trigger-http

Usage

1. On your home machine/server/raspberrypi (ideally the one that runs 24/7), setup a cronjob via crontab -e

2. Use this template:

   30 * * * * curl -s "https://{CLOUD_FUNCTION_URL}/?key={YOUR_SECRET_KEY}&zone={YOUR_MANAGED_DNS_ZONE}&domain={YOUR_DNS_ENTRY_NAME}." >> /tmp/diydyndns-domain.log 2>&1

   ❗ Yes, there is dot at the end of the domain entry - e.g.: subdomain.domain.tld.

   ℹ️ This will run every 30 minutes, but you can adjust this number in the beginning of the line (from 30 to 60 for example).

3. Check the /tmp/diydyndns-domain.log to see if it's working. By default it runs every 30 minutes.

License

Apache License 2.0. See the LICENSE file.