Default variable DROP_TRACE_MESSAGE_LEVELS in pipeline

Author: Chris Wiechmann

.github/workflows/logstash.yml

@@ -57,7 +57,7 @@ jobs:
       env:
         API_BUILDER_URL: 'http://localhost:8080'
         MEMCACHED: 'localhost:11211'
-        DROP_TRACE_MESSAGE_LEVELS: DEBUG
+        DROP_TRACE_MESSAGE_LEVELS: 'DEBUG'
         # This is not relevant as we test with HTTP
         # But it's required by Logstash to be a valid certificate
         API_BUILDER_SSL_CERT: "./config/certificates/apibuilder4elastic.crt"

logstash/pipelines/TraceMessagesPipeline.conf

@@ -13,7 +13,7 @@ filter {
     match => { "message" => "%{LOGLEVEL:level}%{SPACE}(?<loggedDate>\d{2}\/.{3}\/\d{4}:\d{2}:\d{2}:\d{2}\.\d{3})%{SPACE}\[%{WORD:fluff}\:%{WORD:correlationId}\]\s?%{GREEDYDATA:body}" }
   }
   mutate {
-    add_field => { "[@metadata][dropLevels]" => "${DROP_TRACE_MESSAGE_LEVELS}" }
+    add_field => { "[@metadata][dropLevels]" => "${DROP_TRACE_MESSAGE_LEVELS:}" }
   }
   if( [level] in [@metadata][dropLevels] ) {
     drop { id => "Log-Level based drop" }