DDNS Client using Google Cloud DNS

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Background

It's a pretty common requirement for the folks who want to host some service at their home and expose it to the public network, for example I have a NAS at home and would like to access the admin UI remotely. I use PPPoE to connect to the public Internet, and my ISP usually won't give me a static IPv4 address, they will constantly renew it like weekly or whenever they wish to.

Most of modern routers now have build-in support for DDNS, and we have lots of well-known service providers, some of them even have free-tier product but requires a constant renew every month.

If you've already got your own domain name(like me) and prefer to reuse it, things could be a little bit different. Obviously you can continue to use DDNS products, and create a CNAME record point to the hostname supplied by DDNS service provider, but when people do a nslookup, that hostname will be exposed in the result.

To avoid that, I'm more preferred use my own way to update A record automatically when IP changes been detected. Here comes my Google Cloud DNS based solution.

Prerequisites

• You have a project hosted in Google Cloud Platform.
• The DNS record sets of your domain are managed in Google Cloud DNS.
• You can run Docker in your local environment.

How-To

Create an service account with limited permissions

1. Sign-in to Google Cloud Console
2. Go to IAM & Admin -> Roles
3. Create a new role named DDNS Client for example with the following permissions
   • dns.changes.create
   • dns.changes.get
   • dns.changes.list
   • dns.dnsKeys.get
   • dns.dnsKeys.list
   • dns.managedZoneOperations.get
   • dns.managedZoneOperations.list
   • dns.managedZones.get
   • dns.managedZones.list
   • dns.managedZones.update
   • dns.projects.get
   • dns.resourceRecordSets.create
   • dns.resourceRecordSets.delete
   • dns.resourceRecordSets.list
   • dns.resourceRecordSets.update
   • resourcemanager.projects.get
4. Go to IAM & Admin -> Service Accounts
5. Click the + CREATE SERVICE ACCOUNT button on the top, give it a reasonable name like ddns-client.
6. Click CREATE button.
7. Use the drop down menu next to Select a role to pickup the role we just created.
8. Click CONTINUE button.
9. Click + CREATE KEY, use JSON as type which should be default, then click the CREATE button, then you should be able to save the key file, store it securely, and we're going to need it later.
10. Click DONE button, then you will be redirected back to the service account list.

Spin up the client

docker run -d --restart=unless-stopped \
    --name=google-ddns \
    -e ZONE=<your zone name> \
    -e DOMAIN_NAME=<your domain name> \
    -e PROXY_TYPE=<type of proxy, http or socks5 for instance> \
    -e PROXY_ADDR=<IP address or hostname of proxy> \
    -e PROXY_PORT=<Port of proxy> \
    -v <path to json file>:/credential \
    sgrio/google-ddns

Please be sure you've replaced <your zone name>, <your domain name> and <path to json file> in above command to actual values.

I'm more prefer to use a sub-domain like home.example.com instead of go with top level domain name.

You're all set!

You should be able see the record been created within 5 mins.

Troubleshooting

• You can use the following command to view logs from Docker container.

docker logs -f goodle-ddns