add libvirt nodeinfo datasource

[memetb]

This feature allows querying the host machine's nodeinfo through the libvirt protocol.

This is useful for, among other things, obtaining the target machine's architecture to select a guest image.

// main.tf
provider "libvirt" {
  uri = "qemu+ssh://${var.target}/system?sshauth=privkey&no_verify"
}

data "libvirt_nodeinfo" "host" {}

locals {
  arch = data.libvirt_nodeinfo.host.arch
  images = {
    "debian-x86_64" = "/srv/images/debian-12-backports-generic-amd64.qcow2",
    "debian-aarch64"  = "/srv/images/debian-12-backports-generic-arm64.qcow2",
  }
  image_path = local.images["debian-${local.arch}"]
}

output image_path {
  value = local.image_path
}

Which will create the following output:

$~/terraform-provider-libvirt/testing$ TF_VAR_target=chromium terraform apply 
data.libvirt_nodeinfo.host: Reading...
data.libvirt_nodeinfo.host: Read complete after 1s [id=d4e1bf70-6374-45b7-a970-fb584a1b4062]

Changes to Outputs:
  + image_path = "/srv/images/debian-12-backports-generic-arm64.qcow2"

You can apply this plan to save these new output values to the Terraform state, without changing any real infrastructure.

Do you want to perform these actions?
  Terraform will perform the actions described above.
  Only 'yes' will be accepted to approve.

  Enter a value: yes

Apply complete! Resources: 0 added, 0 changed, 0 destroyed.

Outputs:

image_path = "/srv/images/debian-12-backports-generic-arm64.qcow2"
$~/terraform-provider-libvirt/testing$ terraform show 
# data.libvirt_nodeinfo.host:
data "libvirt_nodeinfo" "host" {
    arch                      = "aarch64"
    cores                     = 2
    dies                      = 1
    features                  = [
        "fp",
        "asimd",
        "evtstrm",
        "aes",
        "pmull",
        "sha1",
        "sha2",
        "crc32",
        "cpuid",
    ]
    host                      = "qemu+ssh://chromium/system?sshauth=privkey&no_verify=true"
    id                        = "d4e1bf70-6374-45b7-a970-fb584a1b4062"
    live_migration_support    = true
    live_migration_transports = [
        "tcp",
        "rdma",
    ]
    model                     = "cortex-a72"
    sockets                   = 1
    threads                   = 1
    topology                  = []
    vendor                    = "ARM"
}

Outputs:

image_path = "/srv/images/debian-12-backports-generic-arm64.qcow2"

[memetb]

My bad, this appears to have been merged in #1042 - after I started the feature, before I pushed this PR.

[memetb]

I've made this a draft until the issue #1074 is discussed

[dmacvicar]

See https://github.com/dmacvicar/terraform-provider-libvirt/issues/1074#issuecomment-2351579927

[memetb]

Ok, cool. Fyi, there's definitely some inappropriate usage of log.Fatal in here as well, ;)

[dmacvicar]

As discussed with @memetb in #1074:

Looking at the virsh nodeinfo implementation, it is using virNodeGetInfo.

cmdCapabilities is implemented with virConnectGetCapabilities.

So, I think it make sense to separate them. The prefix could be host, or just nothing (I am leaning towards host). It also does not matter that the topology is not fully implemented, as long it is documented.

[memetb]

@dmacvicar I have updated this PR. As per comment commit 07478ac, I've rolled back any and all changes to nodeinfo and I'm leaving the bugs in there as an open issue to be fixed in a separate PR.

With regards to naming, after looking at the naming of the library I have come to think that maybe we can altogether drop the host prefix from the capabilities, as this is not the API call itself but rather the call returns data which is divided into "host" and "guest" structures.

Usage would look like so:

// main.tf
terraform {
  required_version = ">= 0.13"
  required_providers {
    libvirt = {
      #source  = "dmacvicar/libvirt"
      source = "terraform.local/local/libvirt"
      version = "1.0.0"

    }
  }
}

provider "libvirt" {
  uri = "qemu:///system?no_verify=true"
}

data "libvirt_node_info" "host" {}
data "libvirt_capabilities" "capabilities" {}

output node_info {
  value = data.libvirt_node_info.host
}

output capabilities{
  value = data.libvirt_capabilities.capabilities
}

I have not added any documentation at all. This PR is still a WIP, please let me know about next steps.