Addresses and fallback

A machine can answer on more than one address:

machines:
  - name: main
    hosts:
      - tailscale:vps
      - 203.0.113.10

devmachine tries each in order and uses the first one that answers, printing which on stderr. A public address can stop working for you while it keeps working for everyone else — a provider’s network can drop your traffic, your own can block a port. A second address costs one line and turns an outage into a slower connection.

tailscale: entries

An address written tailscale:<name> is resolved by asking the tailscale command where that machine is.

When tailscale is not installed, or does not know that name, devmachine drops that entry and tries the next address — not an error, since that is what the other addresses are for. If you do not use Tailscale, you never have to care this format exists; if you do, your network being down should not lock you out.

Only running out of addresses is an error, saying what was dropped and why:

no address left to try: tailscale:vps (tailscale is not installed)

Answered, or refused?

These are different problems, and devmachine tells them apart:

machine "main": no address answered: 203.0.113.10 (dial tcp: i/o timeout)

Nothing is listening, or nothing can reach it — check the network, the port, the firewall.

machine "main" answered on 203.0.113.10 but refused the login for "bob": ...

The machine is there; the account or key is the problem. Reporting both as “nothing answered” would send you to check a network that was never at fault.