Merge ~barryprice/charm-canonical-livepatch/+git/trusty-handlers:master into ~livepatch-charmers/charm-canonical-livepatch:master

[Barry Price]

Reinstate special handlers for Trusty (reverses commits 1b039b3 and a471703)

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

This merge proposal is being monitored by mergebot. Change the status to Approved to merge.

[Stuart Bishop (stub)]

Looks good. Might want to look into layer:status for future work, per inline comments.

review: Approve

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

Change successfully merged at revision 94997e25ea249a3138a0f2d1d8a208d6b596a646

diff --git a/reactive/canonical_livepatch.py b/reactive/canonical_livepatch.py
index 533e5a7..f9c1e6e 100644
--- a/reactive/canonical_livepatch.py
+++ b/reactive/canonical_livepatch.py
@@ -4,6 +4,7 @@ from charms.reactive.flags import register_trigger
 from charmhelpers.core.host import write_file, is_container
 from charmhelpers.core import hookenv
 from charmhelpers.contrib.charmsupport import nrpe
+from distutils.version import LooseVersion
 from os import environ, mkdir, path, uname
 from subprocess import check_call, check_output, CalledProcessError
 from time import sleep
@@ -57,6 +58,9 @@ def get_livepatch_status():
     livepatch_status = ''
     try:
         livepatch_status = check_output(cmd, universal_newlines=True)
+    except FileNotFoundError:
+        # If the snap's not installed yet, don't crash out
+        pass
     except CalledProcessError:
         # If the service hasn't been enabled yet, we'll get a process error - this is fine
         pass
@@ -173,10 +177,7 @@ def livepatch_supported():
 def install_livepatch():
     config = hookenv.config()
     snap_channel = config.get('snap_channel')
-    snap.install(
-       'canonical-livepatch',
-       **{'channel': snap_channel, }
-    )
+    snap.install('canonical-livepatch', **{'channel': snap_channel, })
 
 
 @when('snap.installed.canonical-livepatch')
@@ -209,10 +210,17 @@ def proxy_settings():
 @when('livepatch-proxy.configured')
 @when_not('canonical-livepatch.connected')
 def canonical_livepatch_connect():
+    # So if we've just installed snapd on a trusty system, we will not be on
+    # the HWE kernel yet and unfortunately need to reboot first!
+    current = LooseVersion(uname()[2])
+    required = LooseVersion('4.4')
     uptrack_path = '/usr/sbin/uptrack-upgrade'
     if path.exists(uptrack_path):
         hookenv.log('Ksplice/Uptrack detected, please remove it and reboot')
         unit_update('blocked', 'Remove ksplice and then reboot')
+    elif current < required:
+        hookenv.log('Reboot required, kernel {} is too old'.format(current))
+        unit_update('blocked', 'A reboot is required')
     else:
         unit_update('maintenance', 'Connecting to the livepatch service')
         # Make sure the service is ready for us
@@ -224,6 +232,9 @@ def canonical_livepatch_connect():
 @when('canonical-livepatch.connected')
 @when_not('config.changed.livepatch_key', 'canonical-livepatch.active')
 def init_key():
+    # If deployed under Trusty before rebooting into the HWE kernel
+    # the config-changed hook won't fire post-reboot as the state
+    # isn't tracked, but we didn't initialise yet! So, handle it here
     activate_livepatch()
 
 
@@ -239,10 +250,7 @@ def change_channel():
     config = hookenv.config()
     snap_channel = config.get('snap_channel')
     # refresh to the given channel
-    snap.refresh(
-       'canonical-livepatch',
-       **{'channel': snap_channel, }
-    )
+    snap.refresh('canonical-livepatch', **{'channel': snap_channel, })
 
 
 # Set up Nagios checks when the nrpe-external-master subordinate is related