Debian VM MAC addresses changing

[macadameane]

Hello all! I appreciate anyone helping me out ahead of time.

I am running many instances of Debian 10.3 in a VMWare VMs. I have many adapters, and the VM is getting used as an FRR router. I am writing software that configures multiple routers for test networks.

Each machine has 7 network adapters and as the titles indicates, they change sometimes when I run configurations over SSH. I'm not sure exactly when the change occurs, but probably as interfaces get brought up or down. I have verified that the MACs aren't changing in vSphere, and when I restart any of the machines, their MACs return to the expected address and all is well.

I researched the issue quite a bit and can't seem to figure out why this is happening. I am trying to prevent this for configuration consistency. FRR requires me to use the name of the interface when configuring its static address, and I have to match that to the adapters I've connected in vSphere. I already reached out the the FRR slack group and was told that FRR doesn't touch the MACs at all. I never delete the interfaces in vSphere, but I do disconnect them according to the network configuration.

Any ideas?

Thanks again for taking the time to read.

[macadameane]

Just for anyone curious, I did discover what the problem is. vSphere is resetting the MAC addresses only when adapters are modified through its REST API. Other methods don't seem to be problematic. It's a bug as the REST API documentation explicitly states that certain calls will not change the state of items not updated, but they do anyway. Sorry for the trouble.