feat: add UnattendedInstall config and controller

Replace the deprecated v1alpha1 `.machine.install` section with a new
`UnattendedInstall` multi-document config kind, driven by a dedicated
`UnattendedInstallController` (single-flight, no reboot) that exposes an
`UnattendedInstallStatus` resource.

- Deprecate `.machine.install`; no longer required in validation.
- Gate behind version contract (>= 1.14); `talosctl gen config` and
  `cluster create` emit `UnattendedInstall` by default for new contracts,
  translating `--install-disk` into a CEL disk selector.
- Source `legacyBIOSSupport`/`grubUseUKICmdline` from the new document in
  the installer, falling back to `.machine.install`.
- Skip the legacy install sequence (and its reboot) when the document is
  present; install is reconciled out-of-band.

Signed-off-by: Mateusz Urbanek <mateusz.urbanek@siderolabs.com>

Author: shanduur

api/resource/definitions/runtime/runtime.proto

@@ -221,6 +221,13 @@ message ServicePIDSpec {
   string mount_namespace = 2;
 }
 
+// UnattendedInstallStatusSpec describes the unattended install status.
+message UnattendedInstallStatusSpec {
+  string image = 2;
+  string phase = 4;
+  string error = 5;
+}
+
 // UniqueMachineTokenSpec is the spec for the machine unique token. Token can be empty if machine wasn't assigned any.
 message UniqueMachineTokenSpec {
   string token = 1;

cmd/installer/cmd/installer/install.go

@@ -73,14 +73,28 @@ func runInstallCmd(ctx context.Context) (err error) {
 			}
 		}
 
-		if config.Machine() != nil && config.Machine().Install().LegacyBIOSSupport() {
-			options.LegacyBIOSSupport = true
-		}
+		// defaults from the deprecated .machine.install section (if present).
+		legacyBIOSSupport := config.Machine() != nil && config.Machine().Install().LegacyBIOSSupport()
 
 		// if we don't have v1alpha1 config (we are in maintenance mode),
 		// or if we have v1alpha1 config, and GrubUseUKICmdline is set to true,
 		// then we should set the option to true
-		if config.Machine() == nil || config.Machine().Install().GrubUseUKICmdline() {
+		grubUseUKICmdline := config.Machine() == nil || config.Machine().Install().GrubUseUKICmdline()
+
+		// the UnattendedInstall document takes precedence over the deprecated .machine.install section.
+		if config.UnattendedInstallConfig() != nil {
+			// legacyBIOSSupport is not supported in the new config.
+			legacyBIOSSupport = false
+
+			// GrubUseUKICmdline is always true when UnattendedInstall is used.
+			grubUseUKICmdline = true
+		}
+
+		if legacyBIOSSupport {
+			options.LegacyBIOSSupport = true
+		}
+
+		if grubUseUKICmdline {
 			options.GrubUseUKICmdline = true
 		}
 	}

hack/release.toml

@@ -305,6 +305,20 @@ trim:
   enabled: true
   interval: 24h0m0s
 ```
+"""
+
+    [notes.unattended_install]
+        title = "Unattended Install Configuration"
+        description = """\
+Talos introduces a new `UnattendedInstall` multi-document config kind which replaces the deprecated `.machine.install`
+section of the v1alpha1 config. The document carries the installer `image` and a `provisioning` section with a CEL
+`volumeSelector` to match the install disk, plus a `wipe` option.
+
+When the `UnattendedInstall` document is present, the install is driven by the new `UnattendedInstallController`
+(exposing an `UnattendedInstallStatus` resource) instead of the legacy install sequence.
+
+`talosctl gen config` and `talosctl cluster create` now generate the `UnattendedInstall` document by default.
+The `.machine.install` field remains supported for backwards compatibility and is still used for older version contracts.
 """
 
 [make_deps]