Share an app on your computer with friends

You built something in a VM on your laptop, and a friend wants to open it on their phone. The internet cannot reach that VM, and Lima forwards its ports only to your own computer’s 127.0.0.1.

Two ways out. With a VPS and a domain, your VPS serves https://demo.example.com and passes each visit to the VM over your private network. With no VPS, Tailscale Funnel gives the VM a public ts.net address.

You need: a local VM called laptop, a Tailscale account (or your own Headscale), and Tailscale on your own computer. For your own domain: a devmachine VPS called vps, with Caddy, on the same network.

Before you start: machine, skills, workspace

devmachine machines create-local laptop --add
devmachine skills add
devmachine workspaces new acme --machine laptop
devmachine sync --machine laptop

The Lima guide explains each line. --machine laptop picks the VM, since you also have vps.

By hand

1. Put the VM on your private network

On your computer. Your VPS must already be on the same network.

devmachine packages add tailscale --machine laptop
devmachine sync --machine laptop
devmachine login tailscale --machine laptop

devmachine packages add tailscale --machine laptop
devmachine machines edit laptop --set tailscale.login_server=https://net.example.com
devmachine sync --machine laptop
devmachine login tailscale --machine laptop

Once the VM has joined, devmachine adds tailscale:<name> to the top of laptop’s hosts in config.yml. A Lima VM’s name is lima-laptop.

2. Start the app

Inside the workspace (devmachine ssh acme):

mkdir -p ~/demo && cd ~/demo
echo '<h1>Hello from acme</h1>' > index.html
python3 -m http.server 3000 --bind 0.0.0.0

Listen on 0.0.0.0, not 127.0.0.1: the VPS comes in over the VM’s Tailscale address, and 127.0.0.1 answers only the VM itself. Close the terminal; the app keeps running in tmux.

3. Publish it through your VPS

On your computer:

devmachine expose add acme 3000 --host demo.example.com --via vps --publish

The VPS’s Caddy answers demo.example.com, gets the certificate, and proxies to the VM. Your friend opens https://demo.example.com.

How --via works, and what to do when it warns: expose a home server.

4. Take it down

On your computer:

devmachine expose rm demo.example.com

No VPS? Use Tailscale Funnel

Funnel lets Tailscale’s relays carry public traffic to the VM. It is Tailscale’s own service: Headscale does not offer it.

First allow it in your tailnet: MagicDNS, HTTPS and the funnel node attribute (the Funnel docs show how).

After steps 1 and 2, run it as the VM’s admin, since the workspace account has no sudo:

devmachine ssh --machine laptop
sudo tailscale funnel 3000

It prints https://<name>.<tailnet>.ts.net; send that to your friend. Ctrl-C stops it. Funnel is in beta, gives no custom domain, and listens only on ports 443, 8443 and 10000.

With your agent

Open a session on your own computer (devmachine skills add taught it the CLI) and say:

Add tailscale to my local machine laptop, start a static page on port 3000
in workspace acme, and publish it at demo.example.com through my VPS.

The agent adds the package, asks before sync, starts the app and runs expose add --via vps. You still finish devmachine login tailscale yourself: open its URL, or paste the Headscale key.

Check it: from your phone, on mobile data, https://demo.example.com shows “Hello from acme”.

Limits

• Your computer has to be awake, and the VM running. When it sleeps, your friend gets a 502 (or nothing, with Funnel).
• Your computer has to be on the private network when you run expose add, since it looks up the VM’s address. If not, it stops with no address of laptop another machine can reach: no address but a loopback one.
• It is public. Anybody with the link gets in, so share no admin panels. expose rm (or Ctrl-C on Funnel) closes it.

Source: Tailscale Funnel, tailscale funnel command