update doc

.gitignore

@@ -9,4 +9,5 @@ target/
 .project
 .settings/
 .classpath
-dependency-reduced-pom.xml
+dependency-reduced-pom.xml
+codemr/

README.md

@@ -29,6 +29,17 @@ Provide availability to expose:
 - custom metrics (developer's responsibility)
 - resource utilization metrics ([DefaultExports.initialize();](https://github.com/prometheus/client_java/blob/master/simpleclient_hotspot/src/main/java/io/prometheus/client/hotspot/DefaultExports.java))
 
+## Keep in mind
+- Some of metrics are registered when client initialized
+- Some of metrics are registered when client start communicate with kafka cluster   
+- Some of metrics are registered when client communicates with specific (f.e. authentication)
+- Metrics could be removed
+- Application can have several instances of kafka-clients (could be different APIs)
+- `Metrics` is registered in JMX via domains depends on which API is in use
+- Each domain has own set of metric type (metric's group)
+- Stream API is special, because it is register 4 domains (`kafka.streams`, `kafka.consumer`, `kafka.peorducer`, `kafka.admin.client`) and have all set of metric's group from these domains.
+- `NB!`: Metrics has INFO and DEBUG log level. Current implementation support only `INFO` level. (@see [Stream](###Stream)) 
+
 ## Metrics types
 Metrics with Attributes. [Reference](https://github.com/prometheus/jmx_exporter/pull/305/commits/92a6eb106e84cd441ba9b6123132395738d6acd6)
 Name of `metrics group` (prometheus context) or `metric type` (jmx context)
@@ -45,7 +56,7 @@ Name of `metrics group` (prometheus context) or `metric type` (jmx context)
 * `consumer-fetch-manager-metrics` =  fetch-manager metrics + per topic + per partition
 * `consumer-node-metrics` = common clients metrics
 
-### Stream:
+###Stream:
 Stream contains metrics from domains `kafka.producer`, `kafka.consumer`, `kafka.admin.client` and own set of metrics
 such as :
 * `app-info` @deprecated = common clients metrics
@@ -56,10 +67,14 @@ such as :
 * `stream-record-cache-metrics` = stream record cache related metrics [DEBUG lvl]
 * `stream-buffer-metrics` = stream buffer related metrics [DEBUG lvl]
 
-`NB!`: Metrics has info and debug log level. Current implementation support only `INFO` level 
+
 ### References
 - [Issue 305: Add kafka client example config](https://github.com/prometheus/jmx_exporter/pull/305#issuecomment-412851484)
 - [Issue 400: does the client automatically publish jmx mertices (heap size memory, thread number)?](https://github.com/prometheus/client_java/issues/400)
 - [Blog post: JMX monitoring + Java custom metrics.](https://sysdig.com/blog/jmx-monitoring-custom-metrics/)
 - [Kafka metrics reporter](https://github.com/apache/kafka/blob/2.0.0/clients/src/main/java/org/apache/kafka/common/metrics/MetricsReporter.java)
 - [IMO - Good example how to make custom collector](https://github.com/joyent/manta-monitor/blob/master/src/main/java/com/joyent/manta/monitor/CustomPrometheusCollector.java)
+- Approaches (POCs) with `org.apache.kafka.common.metrics.MetricReporter`
+    - [kafka-prometheus-metric-reporter](https://github.com/ripa1993/kafka-prometheus-metric-reporter)
+    - [kafka-client-monitoring-poc](https://github.com/sysco-middleware/kafka-client-monitoring-poc)
+- [Micrometer [PR WIP]](https://github.com/micrometer-metrics/micrometer/pull/1173/files)

src/main/java/no/sysco/middleware/prometheus/kafka/template/common/KafkaClient.java

@@ -8,7 +8,7 @@ public enum KafkaClient {
 
     private final String name;
 
-    private KafkaClient(String s) {
+    KafkaClient(String s) {
         name = s;
     }