Merge ~xavpaice/charm-telegraf/+git/telegraf-charm:lp1799583 into ~telegraf-charmers/charm-telegraf:master

[Xav Paice]

Remove conntrack input if not available

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

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

[Paul Gear (paulgear)]

My only concern with this is that if conntrack is enabled sometime after the telegraf charm is installed. Say, on an NGFW where we can't guarantee ordering of the charm hook runs. I think there's a reactive hook somewhere (can't lay my hands on the name of it now) which will trigger when a file's contents change - if that were included as a trigger for reconfiguring the conntrack plugin, I'd be happy with this.

[Paul Gear (paulgear)]

Comments inline. This should work OK as-is, but I think the suggested changes are sufficiently small and simple that they should be done before merge.

review: Approve

[Paul Gear (paulgear)]

LGTM

review: Approve

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

Change successfully merged at revision 90c671d417508144c6ca9235da702c5b18fd3633

diff --git a/reactive/telegraf.py b/reactive/telegraf.py
index 433829c..afcf181 100644
--- a/reactive/telegraf.py
+++ b/reactive/telegraf.py
@@ -39,6 +39,7 @@ from charms.reactive.bus import get_states
 from charmhelpers import context
 from charmhelpers.core import hookenv, host, unitdata
 from charmhelpers.core.templating import render
+from charmhelpers.core.host import is_container
 from charmhelpers.fetch import apt_cache
 import charms.promreg
 
@@ -50,8 +51,9 @@ CONFIG_FILE = 'telegraf.conf'
 
 CONFIG_DIR = 'telegraf.d'
 
-
 # Utilities #
+
+
 def exec_timeout_supported():
     cache = apt_cache()
     pkg = cache['telegraf']
@@ -132,15 +134,21 @@ def get_remote_unit_name():
                     return rel['__unit__']
 
 
-def render_base_inputs():
+def get_base_inputs():
+    """Make a structure for rendering the base_inputs template.
+    Returns a dict of items for the template.
+    """
     extra_options = get_extra_options()
-    bcache = os.path.exists("/sys/fs/bcache")
+    conntrack = os.path.exists("/proc/sys/net/netfilter/nf_conntrack_max")
+    return {'extra_options': extra_options['inputs'],
+            'bcache': is_bcache(),
+            'conntrack': conntrack}
+
+
+def render_base_inputs():
     # use base inputs from charm templates
     with open(os.path.join(get_templates_dir(), 'base_inputs.conf'), 'r') as fd:
-        return render_template(
-            fd.read(),
-            {'extra_options': extra_options['inputs'],
-             'bcache': bcache})
+        return render_template(fd.read(), get_base_inputs())
 
 
 def get_extra_options():
@@ -857,3 +865,21 @@ def start_or_restart():
     else:
         hookenv.status_set('blocked',
                            'Telegraf failed to start. Check config.')
+
+
+def is_bcache():
+    """
+    return true if bcache is present, and this is not a container
+    """
+    container = is_container()
+    return (os.path.exists("/sys/fs/bcache") and not container)
+
+
+@hook('update-status')
+def update_status():
+    changed = charms.reactive.helpers.is_data_changed(
+        'detect_changes',
+        get_base_inputs(),
+        hash_type='sha256')
+    if changed:
+        remove_state('telegraf.configured')
diff --git a/templates/base_inputs.conf b/templates/base_inputs.conf
index 35cf2a7..5da4fb4 100644
--- a/templates/base_inputs.conf
+++ b/templates/base_inputs.conf
@@ -71,16 +71,22 @@
 [[inputs.system]]
   # no configuration
 
-{%- if bcache %}
+{% if bcache -%}
 [[inputs.bcache]]
+
 {%- endif %}
 
 [[inputs.bond]]
+  # no configuration
 
+{% if conntrack -%}
 [[inputs.conntrack]]
 files = ["ip_conntrack_count","ip_conntrack_max", "nf_conntrack_count","nf_conntrack_max"]
 
+{%- endif %}
+
 [[inputs.cgroup]]
+  # no configuration
 
 [[inputs.exec]]
 commands = [