fix: mitigate inexistent inventory groups

templates/filebeat.yml.j2

@@ -6,7 +6,7 @@ filebeat.config.modules:
 # ================================== General ===================================
 fields_under_root: true
 
-{% if inventory_hostname in groups.docker %}
+{% if inventory_hostname in groups.docker | default([]) %}
 # ================================ AutoDiscover ================================
 filebeat.autodiscover:
   providers:
@@ -32,7 +32,7 @@ output.logstash:
   ssl.certificate_authorities:
     - /etc/ssl/certs/logstash.crt
 
-{% if inventory_hostname in groups.docker_elk %}
+{% if inventory_hostname in groups.docker_elk | default([]) %}
 
 # ---------------------------- ElasticSearch Output -----------------------------
   #output.elasticsearch: