Create host.rancher-desktop.internal and host.docker.internal aliases

[jandubois]

as symbolic names to access a service running on the host from inside the VM.

Implements #893 for Linux and macOS

lima-rancher-desktop:/Users/jan$ ping host.rancher-desktop.internal
PING host.rancher-desktop.internal (192.168.5.2): 56 data bytes
64 bytes from 192.168.5.2: seq=0 ttl=42 time=0.159 ms
64 bytes from 192.168.5.2: seq=1 ttl=42 time=0.335 ms
64 bytes from 192.168.5.2: seq=2 ttl=42 time=0.128 ms
^C

[ericpromislow]

Should we capture the rest of the line in a \(.*\) group and echo it out? Since the line to change comes from the lima-vm repo seems like we should be more flexible to changes there.

[jandubois]

Should we capture the rest of the line in a (.*) group and echo it out?

No, I'm intentionally discarding it. The changes we make are persisted, so we would append the additional names over and over on each reboot otherwise.

If Lima ever adds more than one name to that line, then we have to adapt. But most likely Lima will generate additional lines if/when it wants to define more aliases for the gateway address...

[ericpromislow]

LGTM, with a note about possibly dropping entries.

[djfoxer]

@jandubois Hi! What about Windows? Is host.docker.internal alias will ba available also for Rancher Desktop for Windows?

[jandubois]

@djfoxer Not yet; that is tracked in #893. It is not quite clear yet which address to pick on WSL2, so very likely will not make it into the upcoming release.

[djfoxer]

@jandubois I see. Maybe my code will be useful somehow. I have small workaround for Windows (powershell script):

[updated]

$ip = Get-NetIPAddress -AddressFamily IPv4 -InterfaceIndex $(Get-NetConnectionProfile | Select-Object -ExpandProperty InterfaceIndex) | Select-Object -ExpandProperty IPAddress;
$command = "nerdctl exec container_name  /bin/sh -c `"echo " + $ip + " host.docker.internal >> /etc/hosts`"";
invoke-expression $command

This tiny script takes IP from Windows and add one line to the end of /etc/hosts file in container to translate host.docker.internal into Windows IP. Works for me 😃

[jandubois]

Maybe my code will be useful somehow.

@djfoxer Thank you for sharing! I've linked to it from the other issue, so whoever will work on it sees it.

[djfoxer]

@jandubois Great! I will track this issue.

[dougbreaux]

Hmmm... what's different about my version of PowerShell and yours, @djfoxer ? First I got that "var keyword is not supported", then some missing line terminator stuff, presumably because of the kinds of quotes used. Still trying to work that out...

[dougbreaux]

First command also doesn't seem to produce the same IPs that

wsl -d rancher-desktop ip route

does.

Ahh, this does:

Get-NetIPAddress -AddressFamily IPv4 -InterfaceAlias "vEthernet (WSL)" | Select-Object -ExpandProperty IPAddress

[djfoxer]

@dougbreaux

Hmmm... what's different about my version of PowerShell and yours, @djfoxer ? First I got that "var keyword is not supported", then some missing line terminator stuff, presumably because of the kinds of quotes used. Still trying to work that out...

Sorry, I probably copied wrong code, my current version:

$ip = Get-NetIPAddress -AddressFamily IPv4 -InterfaceIndex $(Get-NetConnectionProfile | Select-Object -ExpandProperty InterfaceIndex) | Select-Object -ExpandProperty IPAddress;
$command = "nerdctl exec container_name  /bin/sh -c `"echo " + $ip + " host.docker.internal >> /etc/hosts`"";
invoke-expression $command

I will update my comment.

[smileart]

When I SSH to lima supplied with Rancher Desktop, I indeed see all the hosts in /etc/hosts, but the containers I'm running in it apparently know nothing about such hosts and their respective /etc/hosts are pretty default. Do I miss something? Cause reaching the host MacOS machine from lima is one thing, but letting containers to do the same, that's what I'd expect from this mechanism as it is with host.docker.internal in Docker Desktop. 🤔

[jandubois]

Do I miss something?

No, this is not working because the built-in resolver in Lima doesn't run inside the VM, it runs on the host to be able to resolve names from VPN etc. This will be fixed by lima-vm/lima#622 (so that Rancher Desktop can add these static names to the lima config).

A workaround would be to add the settings to /etc/hosts on the macOS machine:

192.168.5.2	host.lima.internal host.rancher-desktop.internal host.docker.internal

The names will only work inside the VM and the containers, not on the host. But the 192.168.5.2 IP address is fixed by qemu/lima, so this should work fine (on macOS only).