Ephemeral DNS

A small, NodeJS-based DNS server that dynamically queries outside sources (cloud providers, dynamic DNS, etc.) on-request to get their up-to-date IP address.

Experimental warning

This project is a proof-of-concept and a development hack. It was made to help speed up development around temporary machines (instead of copy-pasting the IP address, or reusing the provider's API library in every language). It can and will change frequently. Later on, it will be stabilised so it could function as a dnsmasq delegate, but for now it is meant for local development only.

Why?

I have a project involving Google Cloud, where machines are spun-up, used remotely and terminated briefly. Querying for each machine's IP during the PoC phase required me to manually open the machine in the control panel and grab the IP. I could also use gcloud compute, but DNS allowed me to use niftier shortcuts like transparently RDP-ing into a full hostname (e.g.: hello-world.gcloud.proxy).

Thus, I looked for small-scale DNS libraries, found node-named and got to work. It was originally Google Cloud-focused, until I realised I could reuse it for all kinds of dynamic names (DDNS, other cloud providers, VPN-routed hosts, pseudo-names, etc.) and thus it was refactored into supporting multiple providers on multiple "domains".

Getting started

1. Clone the repository locally
2. npm install it
3. Copy config.json.example to config.json and configure it appropriately:
   • providers is an array of provider definitions:
     • type corresponds to the class name under /providers
     • params is a dictionary of named-parameters that are provider-specific. See the documentation for providers.
     • bindDomain is the DNS-style "parent domain" which will call this provider. For example, a bindDomain of "hello.world" will delegate "name.hello.world" to that provider but not "full.name.hello.world" or "hello.world".
4. Run with npm start. By default, the server binds to 127.67.76.67 ("127.C.L.D" as in "CLouD"). This can be changed with npm config set ephemeral-dns:ip 1.2.3.4 or by setting bindIp in config.json.
5. Set up your actual DNS resolver/proxy to point any DNS requests for your psuedo-domain into this server. Note it does not redirect queries for domains it doesn't know of.