In #10057, @seigel pointed out an inconsistency in the help text for
`exit-node list` and `set --exit-node`:
1. Use `tailscale exit-node list`, which has a column titled "hostname"
and tells you that you can use a hostname with `set --exit-node`:
```console
$ tailscale exit-node list
IP HOSTNAME COUNTRY CITY STATUS
100.98.193.6 linode-vps.tailfa84dd.ts.net - - -
[…]
100.93.242.75 ua-iev-wg-001.mullvad.ts.net Ukraine Kyiv -
# To view the complete list of exit nodes for a country, use `tailscale exit-node list --filter=` followed by the country name.
# To use an exit node, use `tailscale set --exit-node=` followed by the hostname or IP.
# To have Tailscale suggest an exit node, use `tailscale exit-node suggest`.
```
(This is the same format hostnames are presented in the admin
console.)
2. Try copy/pasting a hostname into `set --exit-node`:
```console
$ tailscale set --exit-node=linode-vps.tailfa84dd.ts.net
invalid value "linode-vps.tailfa84dd.ts.net" for --exit-node; must be IP or unique node name
```
3. Note that the command allows some hostnames, if they're from nodes
in a different tailnet:
```console
$ tailscale set --exit-node= ua-iev-wg-001.mullvad.ts.net
$ echo $?
0
```
This patch addresses the inconsistency in two ways:
1. Allow using `tailscale set --exit-node=` with an FQDN that's missing
the trailing dot, matching the formatting used in `exit-node list`
and the admin console.
2. Make the description of valid exit nodes consistent across commands
("hostname or IP").
Updates #10057
Change-Id: If5d74f950cc1a9cc4b0ebc0c2f2d70689ffe4d73
Signed-off-by: Alex Chan <alexc@tailscale.com>
5b62f98894