dhcp snippets not working in acquired state

[dann frazier]

MAAS 2.9.3-beta1.

DHCP snippets don't seem to be active for nodes in the "Acquired" state, though they work fine when the node is in the "Deploying" state. I discovered this through trial and error. My use case is that I often need to manually test non-MAAS PXE installations on servers that live in our MAAS cluster. It seemed logical that I could Acquire a node (to avoid someone else from grabbing it), install a DHCP snippet to point the node at some other install server, and test that way. But even with such a snippet enabled, the node still boots from the MAAS server. If I instead Deploy the node, the snippet actually starts to be used, and the machine PXE boots from the intended install server (only to obviously fail Deployment later).

The documentation on DHCP snippets[*] doesn't mention a difference in behavior depending on state, so this seems like a bug if not in MAAS. But if not perhaps we should update the docs.

[*] https://maas.io/docs/snap/2.9/ui/managing-dhcp#heading--dhcp-snippets

[Alberto Donato (ack)]

Could you please provide a sample of the DHCP snippet you're using?

[dann frazier (dannf)]

Sure. I use "Type: Machine" snippets that look like:

next-server 10.229.70.43;
filename "grubnetaa64.efi";

[Alberto Donato (ack)]

Could you please provide MAAS' dhcpd.conf (with the snippet enabled) when that machine is deployed and when it's acquired?

[dann frazier (dannf)]

Will a diff do?

--- dhcpd.conf.allocated 2021-09-08 20:01:28.624907214 +0000
+++ dhcpd.conf.deploy 2021-09-08 20:01:43.448306879 +0000
@@ -436,6 +436,18 @@
    hardware ethernet f0:92:1c:b4:d6:30;
    fixed-address 10.229.70.43;
 }
+# bizzy-enp1s0f0
+host 0c-42-a1-49-ee-f4 {
+ #
+ # Node DHCP snippets
+ #
+ # Name: bizzy
+ next-server 10.229.70.43;
+ filename "grubnetaa64.efi";
+
+ hardware ethernet 0c:42:a1:49:ee:f4;
+ fixed-address 10.229.74.89;
+}
 # blanka-enp226s0
 host 5c-ff-35-e

[Alberto Donato (ack)]

Currently, host stanzas in DHCP config are only created when a fixed-address is assigned to the host.
This basically happens either when the PXE interface is set to "static IP" or it's "auto" and the machine is being deployed.

We should indeed investigate always creating the host stanza if there are machine snippets.

As a workaround you could either set a static IP on the interface of that machine, or creating a global snippet with the whole host stanza.

[Jerzy Husakowski (jhusakowski)]

Machine DHCP snippets should be associated with specific machines, instead of being active only when the machine is being acquired/deployed/etc. This change needs to be emphasised in the documentation and release notes.