Every couple of months somebody opens an issue on go-proxmox with a title that starts with json: cannot unmarshal string into Go struct field. The most recent one was fixed last week. It’s the same root cause every time. The Proxmox VE API is backed by Perl, and Perl doesn’t really care whether a scalar is a number or a string. The JSON encoder on the other end writes whatever the scalar happens to be at the time. So a field that is documented as an integer comes back as 2048 from…

I just spent a week of evenings on the access side of go-proxmox. Realms, groups, users and roles all landed. Before any of that, I reworked how a client gets its credentials in the first place. Proxmox gives you two different ways to authenticate. They behave differently enough that it’s worth writing down how each one works on the wire and what the client does with it.

If you start automating Proxmox VE through the API, one thing trips you up first. Almost nothing you ask it to do is finished when the HTTP call returns. Start a VM, clone a template, download an ISO to storage, delete a disk… the response is a single string that looks like a typo. The actual work is happening in a worker process on the node. If your next call depends on that work being done, you have to go find out when it’s done.

Part of a hobby of mine is running a home lab and using on Proxmox VE to do the virtualization. Since I work in the space I’m slowly trying to build tooling around Proxmox that will let me use the home lab full time for work. Usually my work involves building Kubernetes management tooling. You can imagine waiting for public cloud APIs all day can take away hours of your day. That’s at cost to your employer for both your time and the compute resources.