virt-install: Rework install option detection a bit

Add an explicit no_install to Installer to encode that the user is
not expecting an install phase. Use that to determine later if any
install options were specified. This saves later code from having
to deal with installer=None, and is the basis for further clarifications

virt-install

@@ -307,7 +307,7 @@ def validate_required_options(options, guest, installer):
         msg += "\n" + (
             _("--disk storage must be specified (override with --disk none)"))
 
-    if not installer:
+    if not guest.os.is_container() and not installer.options_specified():
         msg += "\n" + (
             _("An install method must be specified\n(%(methods)s)") %
             {"methods": INSTALL_METHODS})
@@ -377,8 +377,6 @@ def build_installer(options, guest):
     install_initrd = None
     install_kernel_args = None
 
-    has_installer = True
-
     if options.install:
         installdata = cli.parse_install(options.install)
 
@@ -415,26 +413,23 @@ def build_installer(options, guest):
             else:
                 extra_args = [installdata.kernel_args]
 
+    no_install = None
     if options.location:
         (location,
          location_kernel,
          location_initrd) = cli.parse_location(options.location)
     elif options.cdrom:
         cdrom = options.cdrom
+        if options.livecd:
+            no_install = True
     elif options.pxe:
         install_bootdev = "network"
-    elif (guest.os.is_container() or
-          options.import_install or
-          options.xmlonly or
-          options.boot or
-          installdata):
+    elif installdata:
         pass
-    else:
-        has_installer = False
-
-    if not has_installer:
-        # This triggers an error in validate_required_options
-        return None
+    elif (options.import_install or
+          options.xmlonly or
+          options.boot):
+        no_install = True
 
     installer = virtinst.Installer(guest.conn,
             cdrom=cdrom,
@@ -444,10 +439,9 @@ def build_installer(options, guest):
             install_bootdev=install_bootdev,
             install_kernel=install_kernel,
             install_initrd=install_initrd,
-            install_kernel_args=install_kernel_args)
+            install_kernel_args=install_kernel_args,
+            no_install=no_install)
 
-    if cdrom and options.livecd:
-        installer.livecd = True
     if options.unattended:
         unattended_data = cli.parse_unattended(options.unattended)
         installer.set_unattended_data(unattended_data)
@@ -543,10 +537,9 @@ def build_guest_instance(conn, options):
     installer = build_installer(options, guest)
     set_cli_defaults(options, guest)
 
-    if installer:
-        installer.set_install_defaults(guest)
-        for path in installer.get_search_paths(guest):
-            cli.check_path_search(guest.conn, path)
+    installer.set_install_defaults(guest)
+    for path in installer.get_search_paths(guest):
+        cli.check_path_search(guest.conn, path)
 
     # cli specific disk validation
     for disk in guest.devices.disk:

virtinst/installer.py

@@ -38,24 +38,27 @@ class Installer(object):
     :param install_kernel_args: Kernel args <cmdline> to use. This overwrites
         whatever the installer might request, unlike extra_args which will
         append arguments.
+    :param no_install: If True, this installer specifically does not have
+        an install phase. We are just using it to create the initial XML.
     """
     def __init__(self, conn, cdrom=None, location=None, install_bootdev=None,
             location_kernel=None, location_initrd=None,
-            install_kernel=None, install_initrd=None, install_kernel_args=None):
+            install_kernel=None, install_initrd=None, install_kernel_args=None,
+            no_install=None):
         self.conn = conn
 
-        self.livecd = False
-
         # Entry point for virt-manager 'Customize' wizard to change autostart
         self.autostart = False
 
-        self._install_bootdev = install_bootdev
         self._install_cdrom_device_added = False
         self._unattended_install_cdrom_device = None
         self._tmpfiles = []
         self._defaults_are_set = False
         self._unattended_data = None
 
+        self._install_bootdev = install_bootdev
+        self._no_install = no_install
+
         self._treemedia = None
         self._treemedia_bootconfig = None
         self._cdrom = None
@@ -267,7 +270,7 @@ class Installer(object):
             os.unlink(f)
 
     def _get_postinstall_bootdev(self, guest):
-        if self.cdrom and self.livecd:
+        if self.cdrom and self._no_install:
             return DomainOs.BOOT_DEVICE_CDROM
 
         if self._install_bootdev:
@@ -350,12 +353,21 @@ class Installer(object):
         into the guest. Things like LiveCDs, Import, or a manually specified
         bootorder do not have an install phase.
         """
-        if self.cdrom and self.livecd:
+        if self._no_install:
             return False
         return bool(self._cdrom or
                     self._install_bootdev or
                     self._treemedia)
 
+    def options_specified(self):
+        """
+        Return True if some explicit install option was actually passed in
+        Validate that some install option was actually passed in.
+        """
+        if self._no_install:
+            return True
+        return self.has_install_phase()
+
     def detect_distro(self, guest):
         """
         Attempt to detect the distro for the Installer's 'location'. If