add rng device option

builder/proxmox/common/config.go

@@ -2,7 +2,7 @@
 // SPDX-License-Identifier: MPL-2.0
 
 //go:generate packer-sdc struct-markdown
-//go:generate packer-sdc mapstructure-to-hcl2 -type Config,NICConfig,diskConfig,vgaConfig,additionalISOsConfig,efiConfig
+//go:generate packer-sdc mapstructure-to-hcl2 -type Config,NICConfig,diskConfig,rng0Config,vgaConfig,additionalISOsConfig,efiConfig
 
 package proxmox
 
@@ -59,6 +59,7 @@ type Config struct {
 	EFIConfig      efiConfig      `mapstructure:"efi_config"`
 	EFIDisk        string         `mapstructure:"efidisk"`
 	Machine        string         `mapstructure:"machine"`
+	Rng0           rng0Config     `mapstructure:"rng0"`
 	VGA            vgaConfig      `mapstructure:"vga"`
 	NICs           []NICConfig    `mapstructure:"network_adapters"`
 	Disks          []diskConfig   `mapstructure:"disks"`
@@ -114,6 +115,50 @@ type efiConfig struct {
 	PreEnrolledKeys bool   `mapstructure:"pre_enrolled_keys"`
 	EFIType         string `mapstructure:"efi_type"`
 }
+
+// - `rng0` (object): Configure Random Number Generator via VirtIO.
+// A virtual hardware-RNG can be used to provide entropy from the host system to a guest VM helping avoid entropy starvation which might cause the guest system slow down.
+// The device is sourced from a host device and guest, his use can be limited: `max_bytes` bytes of data will become available on a `period` ms timer.
+// [PVE documentation](https://pve.proxmox.com/pve-docs/pve-admin-guide.html) recommends to always use a limiter to avoid guests using too many host resources.
+//
+// HCL2 example:
+//
+// ```hcl
+// rng0 {
+//   source    = "/dev/urandom"
+//   max_bytes = 1024
+//   period    = 1000
+// }
+// ```
+//
+// JSON example:
+//
+// ```json
+// {
+//     "rng0": {
+//         "source": "/dev/urandom",
+//         "max_bytes": 1024,
+//         "period": 1000
+//     }
+// }
+// ```
+type rng0Config struct {
+	// Device on the host to gather entropy from.
+	// `/dev/urandom` should be preferred over `/dev/random` as Proxmox PVE documentation suggests.
+	// `/dev/hwrng` can be used to pass through a hardware RNG.
+	// Can be one of `/dev/urandom`, `/dev/random`, `/dev/hwrng`.
+	Source string `mapstructure:"source" required:"true"`
+	// Maximum bytes of entropy allowed to get injected into the guest every `period` milliseconds.
+	// Use a lower value when using `/dev/random` since can lead to entropy starvation on the host system.
+	// `0` disables limiting and according to PVE documentation is potentially dangerous for the host.
+	// Recommended value: `1024`.
+	MaxBytes int `mapstructure:"max_bytes" required:"true"`
+	// Period in milliseconds on which the the entropy-injection quota is reset.
+	// Can be a positive value.
+	// Recommended value: `1000`.
+	Period int `mapstructure:"period" required:"false"`
+}
+
 type vgaConfig struct {
 	Type   string `mapstructure:"type"`
 	Memory int    `mapstructure:"memory"`
@@ -391,6 +436,21 @@ func (c *Config) Prepare(upper interface{}, raws ...interface{}) ([]string, []st
 			errs = packersdk.MultiErrorAppend(errs, errors.New("efi_storage_pool not set for efi_config"))
 		}
 	}
+	if c.Rng0 != (rng0Config{}) {
+		if !(c.Rng0.Source == "/dev/urandom" || c.Rng0.Source == "/dev/random" || c.Rng0.Source == "/dev/hwrng") {
+			errs = packersdk.MultiErrorAppend(errs, errors.New("source must be one of \"/dev/urandom\", \"/dev/random\", \"/dev/hwrng\""))
+		}
+		if c.Rng0.MaxBytes < 0 {
+			errs = packersdk.MultiErrorAppend(errs, errors.New("max_bytes must be greather or equal than 0"))
+		} else {
+			if c.Rng0.MaxBytes == 0 {
+				warnings = append(warnings, "max_bytes is 0: potentially dangerous: this disables limiting the entropy allowed to get injected into the guest")
+			}
+		}
+		if c.Rng0.Period < 0 {
+			errs = packersdk.MultiErrorAppend(errs, errors.New("period must be greather than 0"))
+		}
+	}
 
 	if errs != nil && len(errs.Errors) > 0 {
 		return nil, warnings, errs

builder/proxmox/common/config_test.go

@@ -246,6 +246,89 @@ func TestAdditionalISOs(t *testing.T) {
 
 }
 
+func TestRng0(t *testing.T) {
+	Rng0Test := []struct {
+		name          string
+		rng_config    rng0Config
+		expectFailure bool
+	}{
+		{
+			name:          "no error",
+			expectFailure: false,
+			rng_config: rng0Config{
+				Source:   "/dev/urandom",
+				MaxBytes: 1024,
+				Period:   1000,
+			},
+		},
+		{
+			name:          "empty Source, error",
+			expectFailure: true,
+			rng_config: rng0Config{
+				Source:   "",
+				MaxBytes: 1024,
+				Period:   1000,
+			},
+		},
+		{
+			name:          "negative Period, error",
+			expectFailure: true,
+			rng_config: rng0Config{
+				Source:   "/dev/urandom",
+				MaxBytes: 1024,
+				Period:   -10,
+			},
+		},
+		{
+			name:          "zero Period, noerror",
+			expectFailure: false,
+			rng_config: rng0Config{
+				Source:   "/dev/urandom",
+				MaxBytes: 1024,
+				Period:   0,
+			},
+		},
+		{
+			name:          "malformed Source error, error",
+			expectFailure: true,
+			rng_config: rng0Config{
+				Source:   "/dev/abcde",
+				MaxBytes: 1024,
+				Period:   1000,
+			},
+		},
+		{
+			name:          "negative Period, error",
+			expectFailure: true,
+			rng_config: rng0Config{
+				Source:   "/dev/urandom",
+				MaxBytes: 1024,
+				Period:   -10,
+			},
+		},
+	}
+
+	for _, tt := range Rng0Test {
+		t.Run(tt.name, func(t *testing.T) {
+			cfg := mandatoryConfig(t)
+			cfg["rng0"] = &tt.rng_config
+
+			var c Config
+			_, _, err := c.Prepare(&c, cfg)
+			if err != nil {
+				if !tt.expectFailure {
+					t.Fatalf("unexpected failure to prepare config: %s", err)
+				}
+				t.Logf("got expected failure: %s", err)
+			}
+
+			if err == nil && tt.expectFailure {
+				t.Errorf("expected failure, but prepare succeeded")
+			}
+		})
+	}
+}
+
 func TestSerials(t *testing.T) {
 	serialsTest := []struct {
 		name          string

builder/proxmox/common/step_start_vm.go

@@ -123,6 +123,7 @@ func (s *stepStartVM) Run(ctx context.Context, state multistep.StateBag) multist
 		Bios:         c.BIOS,
 		EFIDisk:      generateProxmoxEfi(c.EFIConfig),
 		Machine:      c.Machine,
+		RNGDrive:     generateProxmoxRng0(c.Rng0),
 		QemuVga:      generateProxmoxVga(c.VGA),
 		QemuNetworks: generateProxmoxNetworkAdapters(c.NICs),
 		QemuDisks:    generateProxmoxDisks(c.Disks),
@@ -295,6 +296,19 @@ func generateProxmoxSerials(serials []string) proxmox.QemuDevices {
 	return devs
 }
 
+func generateProxmoxRng0(rng0 rng0Config) proxmox.QemuDevice {
+	dev := make(proxmox.QemuDevice)
+	setDeviceParamIfDefined(dev, "source", rng0.Source)
+
+	if rng0.MaxBytes >= 0 {
+		dev["max_bytes"] = rng0.MaxBytes
+	}
+	if rng0.Period > 0 {
+		dev["period"] = rng0.Period
+	}
+	return dev
+}
+
 func generateProxmoxVga(vga vgaConfig) proxmox.QemuDevice {
 	dev := make(proxmox.QemuDevice)
 	setDeviceParamIfDefined(dev, "type", vga.Type)

docs-partials/builder/proxmox/common/Config-not-required.mdx

@@ -44,6 +44,8 @@
 
 - `machine` (string) - Machine
 
+- `rng0` (rng0Config) - Rng 0
+
 - `vga` (vgaConfig) - VGA
 
 - `network_adapters` ([]NICConfig) - NI Cs

docs-partials/builder/proxmox/common/rng0Config-not-required.mdx

@@ -0,0 +1,7 @@
+<!-- Code generated from the comments of the rng0Config struct in builder/proxmox/common/config.go; DO NOT EDIT MANUALLY -->
+
+- `period` (int) - Period in milliseconds on which the the entropy-injection quota is reset.
+  Can be a positive value.
+  Recommended value: `1000`.
+
+<!-- End of code generated from the comments of the rng0Config struct in builder/proxmox/common/config.go; -->

docs-partials/builder/proxmox/common/rng0Config-required.mdx

@@ -0,0 +1,13 @@
+<!-- Code generated from the comments of the rng0Config struct in builder/proxmox/common/config.go; DO NOT EDIT MANUALLY -->
+
+- `source` (string) - Device on the host to gather entropy from.
+  `/dev/urandom` should be preferred over `/dev/random` as Proxmox PVE documentation suggests.
+  `/dev/hwrng` can be used to pass through a hardware RNG.
+  Can be one of `/dev/urandom`, `/dev/random`, `/dev/hwrng`.
+
+- `max_bytes` (int) - Maximum bytes of entropy allowed to get injected into the guest every `period` milliseconds.
+  Use a lower value when using `/dev/random` since can lead to entropy starvation on the host system.
+  `0` disables limiting and according to PVE documentation is potentially dangerous for the host.
+  Recommended value: `1024`.
+
+<!-- End of code generated from the comments of the rng0Config struct in builder/proxmox/common/config.go; -->

docs-partials/builder/proxmox/common/rng0Config.mdx

@@ -0,0 +1,30 @@
+<!-- Code generated from the comments of the rng0Config struct in builder/proxmox/common/config.go; DO NOT EDIT MANUALLY -->
+
+- `rng0` (object): Configure Random Number Generator via VirtIO.
+A virtual hardware-RNG can be used to provide entropy from the host system to a guest VM helping avoid entropy starvation which might cause the guest system slow down.
+The device is sourced from a host device and guest, his use can be limited: `max_bytes` bytes of data will become available on a `period` ms timer.
+[PVE documentation](https://pve.proxmox.com/pve-docs/pve-admin-guide.html) recommends to always use a limiter to avoid guests using too many host resources.
+
+HCL2 example:
+
+```hcl
+rng0 {
+  source    = "/dev/urandom"
+  max_bytes = 1024
+  period    = 1000
+}
+```
+
+JSON example:
+
+```json
+{
+    "rng0": {
+        "source": "/dev/urandom",
+        "max_bytes": 1024,
+        "period": 1000
+    }
+}
+```
+
+<!-- End of code generated from the comments of the rng0Config struct in builder/proxmox/common/config.go; -->

docs/builders/clone.mdx

@@ -354,6 +354,18 @@ or responding to pattern `/dev/.+`. Example:
 
 - `machine` - (string) - Set the machine type. Supported values are 'pc' or 'q35'.
 
+#### VirtIO RNG device
+
+@include 'builder/proxmox/common/rng0Config.mdx'
+
+##### Required:
+
+@include 'builder/proxmox/common/rng0Config-required.mdx'
+
+##### Optional:
+
+@include 'builder/proxmox/common/rng0Config-not-required.mdx'
+
 ## Example: Cloud-Init enabled Debian
 
 Here is a basic example creating a Debian 10 server image. This assumes

docs/builders/iso.mdx

@@ -399,6 +399,18 @@ or responding to pattern `/dev/.+`. Example:
 
 - `machine` - (string) - Set the machine type. Supported values are 'pc' or 'q35'.
 
+#### VirtIO RNG device
+
+@include 'builder/proxmox/common/rng0Config.mdx'
+
+##### Required:
+
+@include 'builder/proxmox/common/rng0Config-required.mdx'
+
+##### Optional:
+
+@include 'builder/proxmox/common/rng0Config-not-required.mdx'
+
 ## Boot Command
 
 @include 'packer-plugin-sdk/bootcommand/BootConfig.mdx'