Allow provider configuration to be passed by its caller

[chanster]

System Information

Linux distribution

Ubuntu 22.04

Terraform version

v1.6.4

Provider and libvirt versions

libvirt 0.7.6

---

Checklist

• Is your issue/contribution related with enabling some setting/option exposed by libvirt that the plugin does not yet support, or requires changing/extending the provider terraform schema?

  • Make sure you explain why this option is important to you, why it should be important to everyone. Describe your use-case with detail and provide examples where possible.
  • If it is a very special case, consider using the XSLT support in the provider to tweak the definition instead of opening an issue
  • Maintainers do not have expertise in every libvirt setting, so please, describe the feature and how it is used. Link to the appropriate documentation

• Is it a bug or something that does not work as expected? Please make sure you fill the version information below:

Description of Issue/Question

When calling libvirt resources within a module, it does not support the provider configuration provided by the caller. Having a module to create virtual machines provides a easy way to create them in mass rather than creating multiple similar resources at the root configuration.

lets say I have a module machine in {working_dir}/machine:

Setup

main.tf:

terraform {
  required_providers {
    libvirt = {
      source  = "registry.terraform.io/dmacvicar/libvirt"
      version = "0.7.6"
    }
  }
}

provider "libvirt" {
  uri = "qemu:///session"
}

module "vm" {
  source = "./machine"
  count  = 3
  name   = vm[count.index]
  ...
}

./machine/main.tf:

terraform {
  required_providers {
    libvirt = {
      source  = "registry.terraform.io/dmacvicar/libvirt"
      version = "0.7.6"
    }
  }
}

provider "libvirt" {
  uri = "qemu:///session"
}

resource "libvirt_volume" "root" {
  name           = "${var.name}.qcow2"
  source         = var.vm_image
  size           = 10 * 1024 * 1024 * 1024 # convert GB to bytes
  pool           = var.pool_name
}

resource "libvirt_domain" "main" {
  name = var.name
  vcpu = var.cpus

  cpu {
    mode = "host-passthrough"
  }

  network_interface {
    network_id     = var.network_id
    hostname       = var.hostname == null ? var.name : var.hostname
    addresses      = [var.ip_address]
    wait_for_lease = false
  }

  disk {
    volume_id = libvirt_volume.root.id
    scsi      = "true"
  }
}

Steps to Reproduce Issue

1. Create a module that uses libvirt provider.
2. Call the module created from terraform root configuration.
3. run terraform init

   terraform init
   
   Initializing the backend...
   Initializing modules...
   ╷
   │ Error: Module is incompatible with count, for_each, and depends_on
   │ 
   │   on machines.tf line 16, in module "vm":
   │    16:   count = 3
   │ 
   │ The module at module.machine is a legacy module which contains its own local provider configurations, and so calls to it may not use the count, for_each, or depends_on arguments.
   │ 
   │ If you also control the module "./machine", consider updating this module to instead expect provider configurations to be passed by its caller.

4. removing provider block from ./machines/main.tf allows module to work but no longer runs with correct context of qemu:///session, and defaults to qemu:///system.

   # removed this block
   provider "libvirt" {
     uri = "qemu:///session"
   }

5. Removing terraform block from ./machines/main.tf causes module not correctly resolve.

   │ Error: Failed to query available provider packages
   │ 
   │ Could not retrieve the list of available versions for provider hashicorp/libvirt: provider registry registry.terraform.io does not have a provider named registry.terraform.io/hashicorp/libvirt
   │ 
   │ Did you intend to use dmacvicar/libvirt? If so, you must specify that source address in each module which requires that provider. To see which modules are currently depending on hashicorp/libvirt, run the following
   │ command:
   │     terraform providers

---

Additional information:

Do you have SELinux or Apparmor/Firewall enabled? Some special configuration? No
Have you tried to reproduce the issue without them enabled? n/a

[memetb]

I am working on a PR for this (@dmacvicar)

I too see an important need for this: when writing modules, I may make use of virsh on multiple bare metal nodes to accomplish one orchestration event. I should not know as the caller that there are more than one endpoints.