Add a mirror panel.

This very simply adds a mirror panel to subiquity.
Nothing intelligent at all.  Just defaults to filling with
http://archive.ubuntu.com/ubuntu/ and lets user fill it in.

As implemented here, the mirror only replaces primary mirror,
security will still use http://security.ubuntu.com/ubuntu/

examples/answers.yaml

@@ -8,6 +8,8 @@ Network:
   accept-default: yes
 Proxy:
   proxy: ""
+Mirror:
+  mirror: "http://us.archive.ubuntu.com"
 Filesystem:
   guided: yes
   guided-index: 0

subiquity/controllers/__init__.py

@@ -19,6 +19,7 @@ from .installpath import InstallpathController
 from .installprogress import InstallProgressController
 from .keyboard import KeyboardController
 from .proxy import ProxyController
+from .mirror import MirrorController
 from subiquitycore.controllers.login import LoginController
 from subiquitycore.controllers.network import NetworkController
 from .snaplist import SnapListController
@@ -30,6 +31,7 @@ __all__ = [
     'InstallProgressController',
     'KeyboardController',
     'ProxyController',
+    'MirrorController',
     'LoginController',
     'NetworkController',
     'SnapListController',

subiquity/controllers/mirror.py

@@ -0,0 +1,42 @@
+# Copyright 2018 Canonical, Ltd.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import logging
+
+from subiquitycore.controller import BaseController
+from subiquity.ui.views.mirror import MirrorView
+
+log = logging.getLogger('subiquity.controllers.mirror')
+
+
+class MirrorController(BaseController):
+
+    def __init__(self, common):
+        super().__init__(common)
+        self.model = self.base_model.mirror
+        self.answers = self.all_answers.get('Mirror', {})
+
+    def default(self):
+        self.ui.set_body(MirrorView(self.model, self))
+        if 'mirror' in self.answers:
+            self.done(self.answers['mirror'])
+
+    def cancel(self):
+        self.signal.emit_signal('prev-screen')
+
+    def done(self, mirror):
+        if mirror != self.model.mirror:
+            self.model.mirror = mirror
+        self.signal.emit_signal('next-screen')

subiquity/core.py

@@ -36,6 +36,7 @@ class Subiquity(Application):
             "Installpath",
             "Network",
             "Proxy",
+            "Mirror",
             "Filesystem",
             "Identity",
             "SnapList",

subiquity/models/mirror.py

@@ -0,0 +1,26 @@
+# Copyright 2018 Canonical, Ltd.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import logging
+
+log = logging.getLogger('subiquitycore.models.mirror')
+
+DEFAULT_MIRROR = 'http://archive.ubuntu.com/ubuntu'
+
+
+class MirrorModel(object):
+
+    def __init__(self):
+        self.mirror = DEFAULT_MIRROR

subiquity/models/subiquity.py

@@ -26,6 +26,7 @@ from .installpath import InstallpathModel
 from .keyboard import KeyboardModel
 from .locale import LocaleModel
 from .proxy import ProxyModel
+from .mirror import MirrorModel
 from .snaplist import SnapListModel
 
 
@@ -54,6 +55,7 @@ class SubiquityModel:
         self.filesystem = FilesystemModel(common['prober'])
         self.identity = IdentityModel()
         self.proxy = ProxyModel()
+        self.mirror = MirrorModel()
         self.snaplist = SnapListModel()
 
     def _cloud_init_config(self):
@@ -124,6 +126,9 @@ class SubiquityModel:
             'apt': {
                 'http_proxy': self.proxy.proxy,
                 'https_proxy': self.proxy.proxy,
+                'primary': [{'arches': ["default"],
+                             'uri': self.mirror.mirror}],
+                'preserve_sources_list': False,
                 },
 
             'install': {

subiquity/ui/views/mirror.py

@@ -0,0 +1,64 @@
+# Copyright 2018 Canonical, Ltd.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+""" Mirror View.
+Select the Ubuntu archive mirror.
+
+"""
+import logging
+from urwid import connect_signal
+
+from subiquitycore.view import BaseView
+from subiquitycore.ui.form import (
+    Form,
+    URLField,
+)
+from subiquity.models.mirror import DEFAULT_MIRROR
+
+
+log = logging.getLogger('subiquity.ui.mirror')
+
+mirror_help = _(
+    "You may provide an archive mirror that will be used instead "
+    "of the default '" + DEFAULT_MIRROR + "'")
+
+
+class MirrorForm(Form):
+
+    url = URLField(_("Mirror address:"), help=mirror_help)
+
+
+class MirrorView(BaseView):
+
+    title = _("Configure Ubuntu archive mirror")
+    excerpt = _("If you use an alternative mirror for Ubuntu, enter its"
+                "details here.")
+
+    def __init__(self, model, controller):
+        self.model = model
+        self.controller = controller
+
+        self.form = MirrorForm(initial={'url': self.model.mirror})
+
+        connect_signal(self.form, 'submit', self.done)
+        connect_signal(self.form, 'cancel', self.cancel)
+
+        super().__init__(self.form.as_screen(excerpt=_(self.excerpt)))
+
+    def done(self, result):
+        log.debug("User input: {}".format(result.as_data()))
+        self.controller.done(result.url.value)
+
+    def cancel(self, result=None):
+        self.controller.cancel()