Fix configuration for older fluentd versions (#63)

* Fix regression for previous fluentds
* lower the logging level for custom_fields/custom_dimensions
* Update changelog due to release fix

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 All notable changes to this project will be documented in this file. Tracking did not begin until version 1.10.
 
+<a name="1.7.1"></a>
+# [1.7.1] (2020-04-28)
+- Fix configuration for older fluentd versions [#63](https://github.com/SumoLogic/fluentd-output-sumologic/pull/63)
+
 <a name="1.7.0"></a>
 # [1.7.0] (2020-04-23)
 - Add option for specifing custom fields for logs: [#56](https://github.com/SumoLogic/fluentd-output-sumologic/pull/56)

lib/fluent/plugin/out_sumologic.rb

@@ -186,13 +186,19 @@ def configure(conf)
     end
 
     conf['custom_fields'] = validate_key_value_pairs(conf['custom_fields'])
+    if conf['custom_fields'].nil?
+      conf.delete 'custom_fields'
+    end
     unless conf['custom_fields']
-      @log.info "Custom fields: #{conf['custom_fields']}"
+      @log.debug "Custom fields: #{conf['custom_fields']}"
     end
 
     conf['custom_dimensions'] = validate_key_value_pairs(conf['custom_dimensions'])
+    if conf['custom_dimensions'].nil?
+      conf.delete 'custom_dimensions'
+    end
     unless conf['custom_dimensions']
-      @log.info "Custom dimensions: #{conf['custom_dimensions']}"
+      @log.debug "Custom dimensions: #{conf['custom_dimensions']}"
     end
 
     # For some reason default is set incorrectly in unit-tests