I have a proposal addressing consistency Allow users to spec rancher-users #rancher-desktop

Title

broad-train-31975

12/09/2022, 6:54 PM

I have a proposal addressing consistency: Allow users to specify MAC address for a Lima VM The reason is, some of us use static DHCP, which allows allocating the same IP address for the same MAC address This allows to have a “static” IP without allocating actual static IPs. Benefits? In mixed deployments, when some external services talk to k8s cluster endpoints, it will save time which is needed to reconfigure all external clients in case VM changes IP address. @fast-garage-66093 can we put this in override.yaml file, to avoid dealing with UI?

fast-garage-66093

12/09/2022, 6:57 PM

All the interfaces should already have static IP addresses; do you actually see them change?

Sorry, static MAC addresses

I'm about to join a meeting, but can look it up afterwards: the MAC address should be generated from a static host machine id, and the absolute path name to the VM directory.

You should be able to override it, if you want to specify your own, but the current one should not change over over time, even after factory reset

broad-train-31975

12/09/2022, 7:00 PM

Well, you can’t have a static IP for the external interface rd0, the one connected to a local network. In order to have a static IP here one needs to allocate it from the available IPs on the local network.

I did have a change from .211 to .217 after firewall (which is also DHCP sever) upgrade

the MAC address should be generated from a static host machine id, and the absolute path name to the VM directory.

this will indeed create the same MAC address unless the VM is moved to another directory

But it actually makes sense - different directories, different VMs, different MACs

fast-garage-66093

12/09/2022, 8:52 PM

I've confirmed it, the MAC address is determine by host machine id, full path to the VM, and the index of the interface in your

networks

section in

lima.yaml

If you change your DHCP server, you will get a new IP address because the reservation for the MAC addresses are gone

broad-train-31975

12/09/2022, 8:53 PM

Thus if I edit lima.yaml, the MAC changes, even for the same VM?

Understood about DHCP server - it issues addressed on first come, first served basis - unless it’s a static DHCP IP, of course. This is what happened, and I didn’t have static DHCP for that lima VM at the time

fast-garage-66093

12/09/2022, 8:54 PM

No, only if this order changes:

networks:
  - lima: rancher-desktop-shared
    interface: rd1
  - lima: rancher-desktop-bridged_en0
    interface: rd0

I will have to double-check if we alway emit them in this order, but I would think so

broad-train-31975

12/09/2022, 8:56 PM

if this is inside Lima VM, it wouldn’t matter much - unless someone unintentionally moves things around and reapplies the network settings or reboots the VM

fast-garage-66093

12/09/2022, 8:57 PM

Yes,

rd1

is always first, so they should have static MAC addresses: https://github.com/rancher-sandbox/rancher-desktop/blob/main/pkg/rancher-desktop/backend/lima.ts#L591-L603

You should never edit the

lima.yaml

file. But I just realized that if you add additional networks in

override.yaml

, then they will be defined first, so take over the index from

rd1

(and

rd0

). So maybe don't do that (why would you need more network interfaces?) 🙂

broad-train-31975

12/09/2022, 8:59 PM

Doesn’t seem you’re using netplan, as I thought - and it doesn’t matter

fast-garage-66093

12/09/2022, 9:00 PM

It was always the intention in Lima and RD that MAC addresses are stable, and it looks like they are.

broad-train-31975

12/09/2022, 9:00 PM

So maybe don’t do that (why would you need more network interfaces?)

I currently don’t, but for testing and other purposes, people might

It looks like even if the VM is completely recreated from scratch, the MAC will be the same

fast-garage-66093

12/09/2022, 9:01 PM

Yes, as long as it is stored in the same location again, and uses the same list of interfaces

I haven't tested it, but I also would expect that you can put this into `override.yaml`:

networks:
- interface: rd0
  macAddress: "11:22:33:44:55:66"
- interface: rd1
  macAddress: "..."

broad-train-31975

12/09/2022, 9:05 PM

What is the reason for using rd0 position in the file? Given that it always has the same position, does it contribute to uniqueness of the MAC address at all?

fast-garage-66093

12/09/2022, 9:05 PM

Not sure what happens if you then run RD without sudo, and don't have

rd0

and

rd1

broad-train-31975

12/09/2022, 9:07 PM

I do run with sudo - I want the cluster to be accessible from other comps on my network, say for cases I run test driver on another machine to create a load

fast-garage-66093

12/09/2022, 9:07 PM

The reason is that

rd1

always exists (if you allow sudo), because it is an internal shared network.

rd0

is a bridged network, so if you are offline on a laptop, you may not have any external interface with an IPv4 address, in which case

rd0

would not be created.

broad-train-31975

12/09/2022, 9:08 PM

persistent/sticky DHPC worked as expected

fast-garage-66093

12/09/2022, 9:08 PM

So if

rd0

was first, then the MAC address of

rd1

would change if

rd0

could not be created. This way both MAC addresses are stable (if they exist at all)

broad-train-31975

12/09/2022, 9:10 PM

if you use names of interfaces instead of their position, you won’t have to worry about positions 🙂

fast-garage-66093

12/09/2022, 9:11 PM

Yeah, but the name depends on the interface you are bridging through

So when you are in the office and connected to ethernet, you may bridge through

en0

, but when you are only on wifi you may bridge through

en1

Oh, you mean the interface names...

broad-train-31975

12/09/2022, 9:13 PM

Yup

fast-garage-66093

12/09/2022, 9:13 PM

I can't remember right now why we didn't do that

broad-train-31975

12/09/2022, 9:14 PM

My premise is, if something can be edited, somebody will edit it. And change the order of things

if they change names, too bad, shooting themselves in the foot, so let them but changing the order always seems to be harmless

fast-garage-66093

12/09/2022, 9:15 PM

I think it was because they are optional, if you don't specify them in

lima.yaml

, then lima will assign

lima0

lima1

. etc to them. But we could still have used them for the MAC hash, so I don't know

broad-train-31975

12/09/2022, 9:16 PM

Right… anyways, my problem seems to be solved, and I’ve learned a few things thanks to you 🙂

fast-garage-66093

12/09/2022, 9:16 PM

I don't think we will change anything, as it would change MAC addresses for everyone when they upgrade

broad-train-31975

12/09/2022, 9:16 PM

Yes indeed, and it’ll be breaking change, so you might want to avoid this

fast-garage-66093

12/09/2022, 9:16 PM

So what we have seems "good enough" and you can override by explicitly specifying a

macAddress

if you need to

broad-train-31975

12/09/2022, 9:17 PM

where do I specify the

macAddress

fast-garage-66093

12/09/2022, 9:17 PM

override.yaml

default.yaml

Don't edit

lima.yaml

please! 🙂

broad-train-31975

12/09/2022, 9:17 PM

oh yeah - and this is exactly what I was asking for 🙂

fast-garage-66093

12/09/2022, 9:18 PM

https://rancher-users.slack.com/archives/C0200L1N1MM/p1670619918744489?thread_ts=1670612070.519329&cid=C0200L1N1MM

broad-train-31975

12/09/2022, 9:18 PM

I prefer not to edit anything unless I know what I’m doing

fast-garage-66093

12/09/2022, 9:19 PM

lima.yaml

is edited by RD, and we cannot guarantee that we won't break your changes. That's part of the reason I created the

override.yaml

mechanism to keep user changes separate

broad-train-31975

12/09/2022, 9:19 PM

I haven’t tested it, but I also would expect that you can put this into
override.yaml

That’s exactly where I expected it to be, thank you for confirming!

fast-garage-66093

12/09/2022, 9:20 PM

The thing I had to look up is if network settings are merged, and they are indeed, based on interface name

Some settings are simply concatenated

broad-train-31975

12/09/2022, 9:21 PM

While it’s beyond the current conversation topic, it seems like I can also add interfaces (no need for now) in

override.yaml

, is it the case?

Some settings are simply concatenated

you probably mean merged with user settings having a higher priority… but I’m nitpicking 🙂

fast-garage-66093

12/09/2022, 9:25 PM

I mean concatenated 😛 E.g. provisioning scripts are combined from

override

lima

default

in that order, and there is no merging because they don't have a shared key.

✅ 1

Mounts and networks can merge settings based on a shared key, so you can modify a mount in

override

instead of creating a new one.

DNS settings are taken from the highest priority source, so if they are defined in

override

, then settings in

lima

and

default

are ignore because it doesn't make sense to combine nameserver lists

So every setting may have a specialized behaviour how the final value(s) are determined

broad-train-31975

12/09/2022, 9:29 PM

OK, good to know

fast-garage-66093

12/09/2022, 9:29 PM

Thank you for coming to my TED talk! 😄

😆 1

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