What is PHX.SH?

PHX.SH is just a domain name for local web-app development.

It has DNS entries that point *.phx.sh to 127.0.0.1

This means that you can goto https://my-app.phx.sh:4000 on your computer to access the app you’re working on.

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Why?

HTTP/2 (H2) requires HTTPS (tls). So you will need to use a certificate for local development.

Phoenix has introduced a mix task to generate a self signed certificate for your project. It’s a lot more manageable if you generate a separate certificate for each project so that you can choose to trust (or not trust) them individually.

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How do I Use it?

Run mix phx.gen.cert to generate a certificate to use with your app.

mix phx.gen.cert my-app.phx.sh

You then need to update your config/dev.exs to include the certificate and turn on the strong cipher suite.

config :my_app, MyApp.Endpoint,
       # ...
       https: [
         port: 4000,
         cipher_suite: :strong,
         keyfile: "priv/cert/selfsigned_key.pem",
         certfile: "priv/cert/selfsigned.pem"
       ]

Then run

mix phx.server

And access your application at https://my-app.phx.sh:4000

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I need this to work offline.

For offline use you can add a DNS Entry to /etc/hosts

127.0.0.1               app-name.phx.sh

Or you can use something like dnsmasq. (See setup instructions here: https://gist.github.com/ogrrd/5831371)