Merge lp:~mvo/update-manager/use-screen-in-text-frontend into lp:update-manager

[Michael Vogt]

[Michael Vogt (mvo)]

This branch will automatically use gnu screen if available to run the release upgrader inside a screen window called "ubuntu-release-upgrade-screen-window". If the terminal
goes away for some reason (e.g. network disconnect because of network problem or upgrade
problem) re-connecting and re-running the upgrade command will resume the upgrade.

For a admin running inside screen already nothing should change (except for the name of
the screen window) the command key will work normally. For a admin not using screen the
command key is disabled to avoid confusion with e.g. people used to emacs ctrl-a.

Zombie mode is enabled so that if the upgrade exits the screen content is still visible
for the admin to inspect.

Please let me know if there are any side effects I have not considered.

=== modified file 'DistUpgrade/DistUpgradeMain.py'
--- DistUpgrade/DistUpgradeMain.py	2010-06-09 12:20:44 +0000
+++ DistUpgrade/DistUpgradeMain.py	2010-11-29 14:07:21 +0000
@@ -88,6 +88,9 @@
     # changes
     logging.info("Using config files '%s'" % config.config_files)
     logging.info("uname information: '%s'" % " ".join(os.uname()))
+    return logdir
+
+def save_system_state(logdir):
     # save package state to be able to re-create failures
     system_files = []
     for f in [apt_pkg.Config.find_file("Dir::Etc::preferences"),
@@ -109,7 +112,6 @@
         open(os.path.join(logdir, "lspci.txt"), "w").write(s)
     except OSError, e:
         logging.debug("lspci failed: %s" % e)
-    return logdir
     
 def setup_view(options, config, logdir):
     " setup view based on the config and commandline "
@@ -132,14 +134,53 @@
         sys.exit(1)
     return instance
 
+def check_for_gnu_screen():
+    """ check if there is a upgrade already running inside gnu screen,
+        if so, reattach
+        if not, create new screen window
+    """
+    SCREENNAME = "ubuntu-release-upgrade-screen-window"
+    # get the active screen sockets
+    try:
+        out = subprocess.Popen(
+            ["screen","-ls"], stdout=subprocess.PIPE).communicate()[0]
+        logging.debug("screen returned: '%s'" % out)
+    except OSError:
+        logging.info("screen could not be run")
+        return
+    # check if a release upgrade is among them
+    if SCREENNAME in out:
+        logging.info("found active screen session, re-attaching")
+        # if we have it, attach to it
+        os.execv("/usr/bin/screen",  ["screen", "-d", "-r", "-p", SCREENNAME])
+    # otherwise re-exec inside screen with (-L) for logging enabled
+    os.environ["RELEASE_UPGRADER_NO_SCREEN"]="1"
+    # unset escape key to avoid confusing people who are not used to
+    # screen. people who already run screen will not be affected by this
+    # unset escape key with -e, enable log with -L, set name with -S
+    cmd = ["screen", 
+           "-e", "\\0\\0",
+           "-L", 
+           "-c", "screenrc",
+           "-S", SCREENNAME]+sys.argv
+    logging.info("re-exec inside screen: '%s'" % cmd)
+    os.execv("/usr/bin/screen", cmd)
+
 def main():
-    " main method "
+    """ main method """
     
     # commandline setup and config
     (options, args) = do_commandline()
     config = DistUpgradeConfig(".")
     logdir = setup_logging(options, config)
 
+    # gnu screen support
+    if not "RELEASE_UPGRADER_NO_SCREEN" in os.environ:
+        check_for_gnu_screen()
+
+    # save system state
+    save_system_state(logdir)
+
     from DistUpgradeVersion import VERSION
     logging.info("release-upgrader version '%s' started" % VERSION)
 

=== modified file 'DistUpgrade/DistUpgradeViewText.py'
--- DistUpgrade/DistUpgradeViewText.py	2010-11-26 17:07:20 +0000
+++ DistUpgrade/DistUpgradeViewText.py	2010-11-29 14:07:21 +0000
@@ -32,6 +32,7 @@
 import gettext
 from DistUpgradeGettext import gettext as _
 from utils import wrap, twrap
+import subprocess
 
 class TextFetchProgress(FetchProgress, apt.progress.TextFetchProgress):
     def __init__(self):
@@ -79,29 +80,21 @@
         self._installProgress = InstallProgress()
         sys.excepthook = self._handleException
         #self._process_events_tick = 0
-        #self._check_for_gnu_screen()
-    
-    def _check_for_gnu_screen(self):
-        if (not "TERM" in os.environ or
-            not os.environ["TERM"] == "screen"):
-            self.information(_("Not running inside screen"),
-                             _("Its recommended to run a server upgrade inside "
-                               "the 'screen' environment."))
 
     def _handleException(self, type, value, tb):
-      import traceback
-      print
-      lines = traceback.format_exception(type, value, tb)
-      logging.error("not handled exception:\n%s" % "\n".join(lines))
-      self.error(_("A fatal error occurred"),
-                 _("Please report this as a bug and include the "
-                   "files /var/log/dist-upgrade/main.log and "
-                   "/var/log/dist-upgrade/apt.log "
-                   "in your report. The upgrade has aborted.\n"
-                   "Your original sources.list was saved in "
-                   "/etc/apt/sources.list.distUpgrade."),
-                 "\n".join(lines))
-      sys.exit(1)
+        import traceback
+        print
+        lines = traceback.format_exception(type, value, tb)
+        logging.error("not handled exception:\n%s" % "\n".join(lines))
+        self.error(_("A fatal error occurred"),
+                   _("Please report this as a bug and include the "
+                     "files /var/log/dist-upgrade/main.log and "
+                     "/var/log/dist-upgrade/apt.log "
+                     "in your report. The upgrade has aborted.\n"
+                     "Your original sources.list was saved in "
+                     "/etc/apt/sources.list.distUpgrade."),
+                   "\n".join(lines))
+        sys.exit(1)
 
     def getFetchProgress(self):
         return self._fetchProgress

=== added file 'DistUpgrade/screenrc'
--- DistUpgrade/screenrc	1970-01-01 00:00:00 +0000
+++ DistUpgrade/screenrc	2010-11-29 14:07:21 +0000
@@ -0,0 +1,3 @@
+logfile /var/log/dist-upgrade/screenlog.%n
+logtstamp on
+zombie xr
\ No newline at end of file