jmx state metrics

instrumentation/jmx-metrics/javaagent/README.md

@@ -221,6 +221,67 @@ Thus, the above definitions will create several metrics, named `my.kafka.streams
 
 The metric descriptions will remain undefined, unless they are provided by the queried MBeans.
 
+### State Metrics
+
+Some JMX attributes expose current state as a non-numeric MBean attribute, in order to capture those as metrics it is recommended to use the special `state` metric type.
+For example, with Tomcat connector, the `Catalina:type=Connector,port=*` MBean has `stateName` (of type `String`), we can define the following rule:
+
+```yaml
+---
+rules:
+  - bean: Catalina:type=Connector,port=*
+    mapping:
+      stateName:
+        type: state
+        metric: tomcat.connector
+        metricAttribute:
+          port: param(port)
+          connector_state:
+            ok: STARTED
+            failed: [STOPPED,FAILED]
+            degraded: _
+```
+
+For a given value of `port`, let's say `8080` This will capture the `tomcat.connector.state` metric of type `updowncounter` with value `0` or `1` and the `state` metric attribute will have a value in [`ok`,`failed`,`degraded`].
+For every sample, 3 metrics will be captured for each value of `state` depending on the value of `stateName`:
+
+When `stateName` = `STARTED`, we have:
+
+- `tomcat.connector` value = `1`, attributes `port` = `8080` and `connector_state` = `ok`
+- `tomcat.connector` value = `0`, attributes `port` = `8080` and `connector_state` = `failed`
+- `tomcat.connector` value = `0`, attributes `port` = `8080` and `connector_state` = `degraded`
+
+When `stateName` = `STOPPED` or `FAILED`, we have:
+
+- `tomcat.connector` value = `0`, attributes `port` = `8080` and `connector_state` = `ok`
+- `tomcat.connector` value = `1`, attributes `port` = `8080` and `connector_state` = `failed`
+- `tomcat.connector` value = `0`, attributes `port` = `8080` and `connector_state` = `degraded`
+
+For other values of `stateName`, we have:
+
+- `tomcat.connector` value = `0`, attributes `port` = `8080` and `connector_state` = `ok`
+- `tomcat.connector` value = `0`, attributes `port` = `8080` and `connector_state` = `failed`
+- `tomcat.connector` value = `1`, attributes `port` = `8080` and `connector_state` = `degraded`
+
+Each state key can be mapped to one or more values of the MBean attribute using:
+- a string literal or a string array
+- a `_` character to provide default option and avoid enumerating all values.
+
+Exactly one `_` value must be present in the mapping to ensure all possible values of the MBean attribute can be mapped to a state key.
+
+The default value indicated by `_` does not require a dedicated state key. For example, if we want to have `connector_state` metric attribute with values `on` or `off`, we can use:
+```yaml
+          connector_state:
+            on: STARTED
+            off: [STOPPED,FAILED,_]
+```
+In the particular case where only two values are defined, we can simplify further by explicitly defining one state and rely on default for the other.
+```yaml
+          connector_state:
+            on: STARTED
+            off: _
+```
+
 ### General Syntax
 
 Here is the general description of the accepted configuration file syntax. The whole contents of the file is case-sensitive, with exception for `type` as described in the table below.

instrumentation/jmx-metrics/library/src/main/java/io/opentelemetry/instrumentation/jmx/engine/BeanAttributeExtractor.java

@@ -151,7 +151,7 @@ AttributeInfo getAttributeInfo(MBeanServerConnection connection, ObjectName obje
 
           // Verify correctness of configuration by attempting to extract the metric value.
           // The value will be discarded, but its type will be checked.
-          Object sampleValue = extractAttributeValue(connection, objectName, logger);
+          Object sampleValue = getSampleValue(connection, objectName);
 
           // Only numbers can be used to generate metric values
           if (sampleValue instanceof Number) {
@@ -194,6 +194,11 @@ AttributeInfo getAttributeInfo(MBeanServerConnection connection, ObjectName obje
     return null;
   }
 
+  @Nullable
+  protected Object getSampleValue(MBeanServerConnection connection, ObjectName objectName) {
+    return extractAttributeValue(connection, objectName, logger);
+  }
+
   /**
    * Extracts the specified attribute value. In case the value is a CompositeData, drills down into
    * it to find the correct singleton value (usually a Number or a String).
@@ -203,7 +208,7 @@ AttributeInfo getAttributeInfo(MBeanServerConnection connection, ObjectName obje
    *     pattern
    * @param logger the logger to use, may be null. Typically we want to log any issues with the
    *     attributes during MBean discovery, but once the attribute is successfully detected and
-   *     confirmed to be eligble for metric evaluation, any further attribute extraction
+   *     confirmed to be eligible for metric evaluation, any further attribute extraction
    *     malfunctions will be silent to avoid flooding the log.
    * @return the attribute value, if found, or {@literal null} if an error occurred
    */
@@ -253,7 +258,8 @@ private Object extractAttributeValue(MBeanServerConnection connection, ObjectNam
   }
 
   @Nullable
-  Number extractNumericalAttribute(MBeanServerConnection connection, ObjectName objectName) {
+  protected Number extractNumericalAttribute(
+      MBeanServerConnection connection, ObjectName objectName) {
     Object value = extractAttributeValue(connection, objectName);
     if (value instanceof Number) {
       return (Number) value;

instrumentation/jmx-metrics/library/src/main/java/io/opentelemetry/instrumentation/jmx/engine/BeanGroup.java

@@ -5,7 +5,11 @@
 
 package io.opentelemetry.instrumentation.jmx.engine;
 
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
 import javax.annotation.Nullable;
+import javax.management.MalformedObjectNameException;
 import javax.management.ObjectName;
 import javax.management.QueryExp;
 
@@ -16,7 +20,7 @@
 public class BeanGroup {
   // How to specify the MBean(s)
   @Nullable private final QueryExp queryExp;
-  private final ObjectName[] namePatterns;
+  private final List<ObjectName> namePatterns;
 
   /**
    * Constructor for BeanGroup.
@@ -25,17 +29,29 @@ public class BeanGroup {
    * @param namePatterns an array of ObjectNames used to look for MBeans; usually they will be
    *     patterns. If multiple patterns are provided, they work as logical OR.
    */
-  public BeanGroup(@Nullable QueryExp queryExp, ObjectName... namePatterns) {
+  private BeanGroup(@Nullable QueryExp queryExp, List<ObjectName> namePatterns) {
     this.queryExp = queryExp;
     this.namePatterns = namePatterns;
   }
 
+  public static BeanGroup forSingleBean(String bean) throws MalformedObjectNameException {
+    return new BeanGroup(null, Collections.singletonList(new ObjectName(bean)));
+  }
+
+  public static BeanGroup forBeans(List<String> beans) throws MalformedObjectNameException {
+    List<ObjectName> list = new ArrayList<>();
+    for (String name : beans) {
+      list.add(new ObjectName(name));
+    }
+    return new BeanGroup(null, list);
+  }
+
   @Nullable
   QueryExp getQueryExp() {
     return queryExp;
   }
 
-  ObjectName[] getNamePatterns() {
+  List<ObjectName> getNamePatterns() {
     return namePatterns;
   }
 }

instrumentation/jmx-metrics/library/src/main/java/io/opentelemetry/instrumentation/jmx/engine/MetricAttribute.java

@@ -22,6 +22,10 @@ public MetricAttribute(String name, MetricAttributeExtractor extractor) {
     this.extractor = extractor;
   }
 
+  public boolean isStateAttribute() {
+    return extractor == null;
+  }
+
   public String getAttributeName() {
     return name;
   }

instrumentation/jmx-metrics/library/src/main/java/io/opentelemetry/instrumentation/jmx/engine/MetricDef.java

@@ -5,6 +5,8 @@
 
 package io.opentelemetry.instrumentation.jmx.engine;
 
+import java.util.List;
+
 /**
  * A class providing a complete definition on how to create an Open Telemetry metric out of the JMX
  * system: how to extract values from MBeans and how to model, name and decorate them with
@@ -74,7 +76,7 @@ public class MetricDef {
   private final BeanGroup beans;
 
   // Describes how to get the metric values and their attributes, and how to report them
-  private final MetricExtractor[] metricExtractors;
+  private final List<MetricExtractor> metricExtractors;
 
   /**
    * Constructor for MetricDef.
@@ -84,7 +86,7 @@ public class MetricDef {
    *     MetricExtractor is provided, they should use unique metric names or unique metric
    *     attributes
    */
-  public MetricDef(BeanGroup beans, MetricExtractor... metricExtractors) {
+  public MetricDef(BeanGroup beans, List<MetricExtractor> metricExtractors) {
     this.beans = beans;
     this.metricExtractors = metricExtractors;
   }
@@ -93,7 +95,7 @@ BeanGroup getBeanGroup() {
     return beans;
   }
 
-  MetricExtractor[] getMetricExtractors() {
+  List<MetricExtractor> getMetricExtractors() {
     return metricExtractors;
   }
 }

instrumentation/jmx-metrics/library/src/main/java/io/opentelemetry/instrumentation/jmx/engine/MetricExtractor.java

@@ -5,6 +5,7 @@
 
 package io.opentelemetry.instrumentation.jmx.engine;
 
+import java.util.List;
 import javax.annotation.Nullable;
 
 /**
@@ -22,14 +23,14 @@ public class MetricExtractor {
   private final BeanAttributeExtractor attributeExtractor;
 
   // Defines the Measurement attributes to be used when reporting the metric value.
-  private final MetricAttribute[] attributes;
+  private final List<MetricAttribute> attributes;
 
   @Nullable private volatile DetectionStatus status;
 
   public MetricExtractor(
       BeanAttributeExtractor attributeExtractor,
       MetricInfo metricInfo,
-      MetricAttribute... attributes) {
+      List<MetricAttribute> attributes) {
     this.attributeExtractor = attributeExtractor;
     this.metricInfo = metricInfo;
     this.attributes = attributes;
@@ -43,7 +44,7 @@ BeanAttributeExtractor getMetricValueExtractor() {
     return attributeExtractor;
   }
 
-  MetricAttribute[] getAttributes() {
+  List<MetricAttribute> getAttributes() {
     return attributes;
   }
 

instrumentation/jmx-metrics/library/src/main/java/io/opentelemetry/instrumentation/jmx/engine/MetricInfo.java

@@ -19,7 +19,9 @@ public class MetricInfo {
   public enum Type {
     COUNTER,
     UPDOWNCOUNTER,
-    GAUGE
+    GAUGE,
+    /** state metric captured as updowncounter */
+    STATE
   }
 
   // How to report the metric using OpenTelemetry API
@@ -44,21 +46,21 @@ public MetricInfo(
     this.type = type == null ? Type.GAUGE : type;
   }
 
-  String getMetricName() {
+  public String getMetricName() {
     return metricName;
   }
 
   @Nullable
-  String getDescription() {
+  public String getDescription() {
     return description;
   }
 
   @Nullable
-  String getUnit() {
+  public String getUnit() {
     return unit;
   }
 
-  Type getType() {
+  public Type getType() {
     return type;
   }
 }

instrumentation/jmx-metrics/library/src/main/java/io/opentelemetry/instrumentation/jmx/engine/MetricRegistrar.java

@@ -120,6 +120,13 @@ void enrollExtractor(
           }
           logger.log(INFO, "Created Gauge for {0}", metricName);
         }
+        break;
+        // CHECKSTYLE:OFF
+      case STATE:
+        {
+          // CHECKSTYLE:ON
+          throw new IllegalStateException("state metrics should not be registered");
+        }
     }
   }
 
@@ -173,9 +180,8 @@ static Consumer<ObservableLongMeasurement> longTypeCallback(MetricExtractor extr
    */
   static Attributes createMetricAttributes(
       MBeanServerConnection connection, ObjectName objectName, MetricExtractor extractor) {
-    MetricAttribute[] metricAttributes = extractor.getAttributes();
     AttributesBuilder attrBuilder = Attributes.builder();
-    for (MetricAttribute metricAttribute : metricAttributes) {
+    for (MetricAttribute metricAttribute : extractor.getAttributes()) {
       String attributeValue = metricAttribute.acquireAttributeValue(connection, objectName);
       if (attributeValue != null) {
         attrBuilder = attrBuilder.put(metricAttribute.getAttributeName(), attributeValue);