Imagine bitly.com or goo.gl and your hosts file combined
Create a Github Gist or just any plain file hosted somewhere. Gistdirect will grap that file and redirect the alias to the full url.
Sample "host" file:
gh https://github.com
The URL to the file is provided as an environment variable: GIST_URL. Make sure to provide an URL that is a raw textfile. If you use a GitHub Gist click on the raw button before grabbing the URL like https://gist.githubusercontent.com/NiklasMerz/a9b5905f742b5863197a0af0465a39f6/raw/.
It is a simple Go function which is easy to run on any serverless platform. You can also run the binary somewhere and it will listen on port 8080. Executables are avaible from releases.
I got it running with Google Cloud Functions and Firebase hosting. You can deploy the function from "function.go" via the web interface or gcloud CLI. Firebase can be used to assign a custom domain to the function. Firebase CLI and the "firebase.json" file help you to assing the function to the root of the domain.
Gistdirect is on Docker Hub so you can just run:
docker run -p 8080:8080 -e GIST_URL='https://gist.github.com/NiklasMerz/a9b5905f742b5863197a0af0465a39f6/raw/' niklasmerz/gistdirect