Indexed parameters

The Proxmox VE API has parameters that exist once per device: net0, net1, scsi0, scsi1, ipconfig0. In the client each family is one argument, named with an N at the end, of type IDictionary<int, string>: the key is the index, the value is the configuration string that Proxmox VE expects.

var networks = new Dictionary<int, string>
{
    [0] = "model=virtio,bridge=vmbr0,firewall=1",   // net0
    [1] = "model=virtio,bridge=vmbr1,tag=100",      // net1
};

var result = await client.Nodes["pve01"].Qemu[100].Config.UpdateVm(netN: networks);

Only the indexes in the dictionary are sent: the call above leaves net2 as it is. The value of an index replaces the whole device: when you change an existing network device keep its macaddr, or Proxmox VE generates a new one. The most used families:

Argument	Sent as	For
netN	net0, net1, …	Network devices of VMs and containers
scsiN, virtioN, sataN, ideN	scsi0, virtio0, …	Disks and CD-ROM drives of VMs
ipconfigN	ipconfig0, …	Cloud-init IP configuration of VMs
hostpciN, usbN	hostpci0, usb0, …	Passthrough of host devices
mpN	mp0, mp1, …	Mount points of containers

The format of each value is in the description of the parameter in the API viewer, and in the pages of the Proxmox VE administration guide linked below. The client does not check the string: Proxmox VE does, and a wrong one gives status 400 with the reason in GetError().

Network of a VM

model=<model>,bridge=<bridge> followed by options, as described in Network Device.

Option	Meaning	Example
model	Emulated card	virtio, e1000, vmxnet3
bridge	Bridge of the node to attach to	vmbr0
tag	VLAN tag	tag=100
firewall	Apply the Proxmox VE firewall	firewall=1
macaddr	MAC address, generated when left out	macaddr=BC:24:11:00:00:01
rate	Rate limit in MB/s	rate=100
mtu	MTU, virtio only	mtu=9000
queues	Multiqueue, virtio only	queues=4
link_down	Create the device disconnected	link_down=1

Disks of a VM

To create a new disk give the storage and the size in GiB: <storage>:<size>. To attach an existing volume give its id: <storage>:<volume>. Options follow, as described in Hard Disk.

var result = await client.Nodes["pve01"].Qemu[100].Config.UpdateVm(
    scsiN: new Dictionary<int, string>
    {
        [0] = "local-lvm:32,discard=on,iothread=1",      // new 32 GiB disk
        [1] = "local-lvm:100,backup=0",                  // new 100 GiB disk, left out of backups
    },
    ideN: new Dictionary<int, string>
    {
        [2] = "local:iso/debian-13.1.0-amd64-netinst.iso,media=cdrom",
    });

Bus	Indexes	Notes
scsiN	0 to 30	The usual choice, with scsihw: "virtio-scsi-single"
virtioN	0 to 15	VirtIO block
sataN	0 to 5
ideN	0 to 3	Mostly CD-ROM drives

Option	Meaning	Values
cache	Cache mode	none, writethrough, writeback, directsync, unsafe
discard	Pass TRIM to the storage	on, ignore
iothread	Dedicated I/O thread	0, 1
ssd	Present the disk as SSD	0, 1
backup	Include the disk in backups	0, 1
media	Kind of drive	disk, cdrom

The EFI disk and the TPM state exist only once, so they are plain string arguments, efidisk0 and tpmstate0:

var result = await client.Nodes["pve01"].Qemu[100].Config.UpdateVm(
    bios: "ovmf",
    efidisk0: "local-lvm:1,efitype=4m,pre-enrolled-keys=1");

Cloud-init

ipconfigN configures the network device with the same index: ipconfig0 is for net0. See Cloud-Init Support.

var result = await client.Nodes["pve01"].Qemu[100].Config.UpdateVm(
    ciuser: "admin",
    sshkeys: Uri.EscapeDataString(publicKey),
    ipconfigN: new Dictionary<int, string>
    {
        [0] = "ip=192.168.1.100/24,gw=192.168.1.1",   // static
        [1] = "ip=dhcp",                              // DHCP
    });

The API wants sshkeys URL-encoded: encode it yourself, as above.

Containers

Containers use the same pattern with their own formats: netN carries name, bridge and addresses, mpN a volume and its path in the container.

var result = await client.Nodes["pve01"].Lxc[200].Config.UpdateVm(
    netN: new Dictionary<int, string>
    {
        [0] = "name=eth0,bridge=vmbr0,ip=dhcp",
    },
    mpN: new Dictionary<int, string>
    {
        [0] = "local-lvm:8,mp=/var/lib/data",   // new 8 GiB volume mounted at /var/lib/data
    });

In raw calls

With raw calls there is no dictionary: use the names of the API, net0, scsi1. PveClientBase.AddIndexedParameter adds the entries of a dictionary to the parameters with those names:

var parameters = new Dictionary<string, object> { ["memory"] = 4096 };
PveClientBase.AddIndexedParameter(parameters, "net", networks);

var result = await client.SetAsync("/nodes/pve01/qemu/100/config", parameters);

A complete VM, from nothing to started, is in Create a VM.