// Module included in the following assemblies:
//
// assembly-logging-configuration.adoc

[id='creating-logging-filters_{context}']
= Adding logging filters to Strimzi operators

[role="_abstract"]
If you are using a ConfigMap to configure the (log4j2) logging levels for Strimzi operators,
you can also define logging filters to limit what's returned in the log.

Logging filters are useful when you have a large number of logging messages.
Suppose you set the log level for the logger as DEBUG (`rootLogger.level="DEBUG"`).
Logging filters reduce the number of logs returned for the logger at that level, so you can focus on a specific resource.
When the filter is set, only log messages matching the filter are logged.

Filters use _markers_ to specify what to include in the log.
You specify a kind, namespace and name for the marker.
For example, if a Kafka cluster is failing, you can isolate the logs by specifying the kind as `Kafka`, and use the namespace and name of the failing cluster.

This example shows a marker filter for a Kafka cluster named `my-kafka-cluster`.

.Basic logging filter configuration
[source,yaml,subs="+attributes"]
----
rootLogger.level="INFO"
appender.console.filter.filter1.type=MarkerFilter <1>
appender.console.filter.filter1.onMatch=ACCEPT <2>
appender.console.filter.filter1.onMismatch=DENY <3>
appender.console.filter.filter1.marker=Kafka(my-namespace/my-kafka-cluster) <4>
----
<1> The `MarkerFilter` type compares a specified marker for filtering.
<2> The `onMatch` property accepts the log if the marker matches.
<3> The `onMismatch` property rejects the log if the marker does not match.
<4> The marker used for filtering is in the format __KIND(NAMESPACE/NAME-OF-RESOURCE)__.

You can create one or more filters.
Here, the log is filtered for two Kafka clusters.

.Multiple logging filter configuration
[source,yaml,subs="+attributes"]
----
appender.console.filter.filter1.type=MarkerFilter
appender.console.filter.filter1.onMatch=ACCEPT
appender.console.filter.filter1.onMismatch=DENY
appender.console.filter.filter1.marker=Kafka(my-namespace/my-kafka-cluster-1)
appender.console.filter.filter2.type=MarkerFilter
appender.console.filter.filter2.onMatch=ACCEPT
appender.console.filter.filter2.onMismatch=DENY
appender.console.filter.filter2.marker=Kafka(my-namespace/my-kafka-cluster-2)
----

.Adding filters to the Cluster Operator

To add filters to the Cluster Operator, update its logging ConfigMap YAML file (`install/cluster-operator/050-ConfigMap-strimzi-cluster-operator.yaml`).

.Procedure

. Update the `050-ConfigMap-strimzi-cluster-operator.yaml` file to add the filter properties to the ConfigMap.
+
In this example, the filter properties return logs only for the `my-kafka-cluster` Kafka cluster:
+
[source,yaml,subs="+attributes"]
----
kind: ConfigMap
apiVersion: v1
metadata:
  name: strimzi-cluster-operator
data:
  log4j2.properties:
    #...
    appender.console.filter.filter1.type=MarkerFilter
    appender.console.filter.filter1.onMatch=ACCEPT
    appender.console.filter.filter1.onMismatch=DENY
    appender.console.filter.filter1.marker=Kafka(my-namespace/my-kafka-cluster)
----
+
Alternatively, edit the `ConfigMap` directly:
+
[source,shell,subs=+quotes]
----
kubectl edit configmap strimzi-cluster-operator
----

. If you updated the YAML file instead of editing the `ConfigMap` directly, apply the changes by deploying the ConfigMap:
+
[source,shell,subs=+quotes]
----
kubectl create -f install/cluster-operator/050-ConfigMap-strimzi-cluster-operator.yaml
----

.Adding filters to the Topic Operator or User Operator

To add filters to the Topic Operator or User Operator, create or edit a logging ConfigMap.

In this procedure a logging ConfigMap is created with filters for the Topic Operator.
The same approach is used for the User Operator.

.Procedure

. Create the ConfigMap.
+
You can create the ConfigMap as a YAML file or from a properties file.
+
In this example, the filter properties return logs only for the `my-topic` topic:
+
[source,yaml,subs="+attributes"]
----
kind: ConfigMap
apiVersion: v1
metadata:
  name: logging-configmap
data:
  log4j2.properties:
    rootLogger.level="INFO"
    appender.console.filter.filter1.type=MarkerFilter
    appender.console.filter.filter1.onMatch=ACCEPT
    appender.console.filter.filter1.onMismatch=DENY
    appender.console.filter.filter1.marker=KafkaTopic(my-namespace/my-topic)
----
+
If you are using a properties file, specify the file at the command line:
+
[source,shell]
----
kubectl create configmap logging-configmap --from-file=log4j2.properties
----
+
The properties file defines the logging configuration:
+
[source,text]
----
# Define the logger
rootLogger.level="INFO"
# Set the filters
appender.console.filter.filter1.type=MarkerFilter
appender.console.filter.filter1.onMatch=ACCEPT
appender.console.filter.filter1.onMismatch=DENY
appender.console.filter.filter1.marker=KafkaTopic(my-namespace/my-topic)
# ...
----

. Define _external_ logging in the `spec` of the resource, setting the `logging.valueFrom.configMapKeyRef.name` to the name of the ConfigMap and `logging.valueFrom.configMapKeyRef.key` to the key in this ConfigMap.
+
For the Topic Operator, logging is specified in the `topicOperator` configuration of the `Kafka` resource.
+
[source,shell,subs="+quotes,attributes"]
----
spec:
  # ...
  entityOperator:
    topicOperator:
      logging:
        type: external
        valueFrom:
          configMapKeyRef:
            name: logging-configmap
            key: log4j2.properties
----

. Apply the changes by deploying the Cluster Operator:

[source,shell,subs=+quotes]
----
create -f install/cluster-operator -n my-cluster-operator-namespace
----

[role="_additional-resources"]
.Additional resources
* xref:con-config-kafka-kraft-str[Configuring Kafka]
* xref:ref-operator-cluster-logging-configmap-str[Cluster Operator logging]
* link:{BookURLConfiguring}#property-topic-operator-logging-reference[Topic Operator logging^]
* link:{BookURLConfiguring}#property-user-operator-logging-reference[User Operator logging^]
