r/collectd: Ignore filesystems by path

In addition to ignoring particular types of filesystems, e.g. OverlayFS,
we can also ignore filesystems by their mount point.  This could be
useful, for example, for bind-mounted directories, such as those used on
Kubernetes nodes.

group_vars/kubelet.yml

@@ -8,3 +8,7 @@ collectd_processes_controller:
 - name: etcd
 - name: kube-apiserver
 - name: kube-controller
+collectd_df_ignore_mountpoint:
+- /etc/cni/net.d
+- /opt/cni
+- /usr/libexec/kubernetes/kubelet-plugins

roles/collectd/defaults/main.yml

@@ -2,6 +2,7 @@ collectd_default_config: true
 collectd_load_network_plugin: false
 collectd_network_servers: []
 collectd_network_listen: []
+collectd_df_ignore_mountpoint: []
 collectd_df_ignore_fstype:
 - overlay
 

roles/collectd/templates/collectd-df.conf.j2

@@ -6,3 +6,12 @@
     IgnoreSelected true
 </Plugin>
 {% endif %}
+{% if collectd_df_ignore_mountpoint %}
+
+<Plugin df>
+{% for path in collectd_df_ignore_mountpoint %}
+    MountPoint "{{ path }}"
+{% endfor %}
+    IgnoreSelected true
+</Plugin>
+{% endif %}