Merge lp:~tcuthbert/turku-charms/turku-api-charm into lp:turku-charms/turku-api-charm

[Thomas Cuthbert]

Charm changes required to monitor turku backups with Prometheus

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

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

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

Unable to determine commit message from repository - please click "Set commit message" and enter the commit message manually.

[Barry Price (barryprice)]

LGTM +1

review: Approve

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

Change successfully merged at revision 10

=== modified file 'hooks/hooks.py'
--- hooks/hooks.py	2015-10-30 05:09:23 +0000
+++ hooks/hooks.py	2021-02-05 02:25:50 +0000
@@ -14,6 +14,26 @@
     playbook_path='playbook.yml')
 
 
+def am_i_leader():
+    """Calls the is-leader juju helper to determine if server is current leader"""
+    string_to_boolean = {'True': True, 'False': False}
+    call_out = None
+    is_leader = False
+    try:
+        call_out = subprocess.run(['is-leader'], check=True, text=True, timeout=15.0)
+        is_leader = string_to_boolean[call_out.STDOUT]
+    except KeyError:
+        juju_log('ERROR', 'is-leader juju helper returned unexpected value: {}'.format(call_out))
+    except subprocess.CalledProcessError:
+        juju_log('ERROR', 'is-leader juju helper failed to execute: {}'.format(call_out.STDOUT + call_out.STDERR))
+    return is_leader
+
+
+def juju_log(severity, message):
+    cmd = ['juju-log', '--log-level', severity, message]
+    subprocess.check_call(cmd)
+
+
 @hooks.hook('install', 'upgrade-charm')
 def install():
     for f in glob.glob('exec.d/*/charm-pre-install'):
@@ -29,5 +49,21 @@
     charmhelpers.contrib.ansible.install_ansible_support(from_ppa=True)
 
 
[e-mail]('leader-elected', 'leader-settings-changed')
+def leader_elected():
+    # This manual hook exists because calling ansible every leadership event is a bad idea.
+    sick_sources_script = '/srv/turku.admin.canonical.com/code/current/turku_api/scripts/turku_sick_sources'
+    cron_daily_sick_sources = '/etc/cron.daily/sick_sources'
+    is_leader = am_i_leader()
+    if is_leader:
+        # install the script to cron.daily.
+        os.symlink(sick_sources_script, cron_daily_sick_sources)
+    else:
+        # check if script in cron.daily, remove if so.
+        cron_daily_sick_sources = "/etc/cron.daily/sick_sources"
+        if os.path.isfile(cron_daily_sick_sources):
+            os.unlink(cron_daily_sick_sources)
+
+
 if __name__ == "__main__":
-        hooks.execute(sys.argv)
+    hooks.execute(sys.argv)