Positive match to a rule should not consume the metric

[Varga Bence]

The exporter's current behavior is that the first matching rule consumes the metric which will not be visible to subsequent matches. In the example below only the first rule will display any metrics from MyLegacyMetricsBean.

# The old way when I had a single class
- pattern: 'com.example.myproduct.metrics<type=MyLegacyMetricsBean><>([^:]+)'
  name: myproduct_$1
  ...
# The new way with multiple classes
- pattern: 'com.example.myproduct.metrics<type=(.*)><>([^:]+)'
  name: myproduct_$1_$2
  ...

I am doing a refactoring of my metrics and I would like to support the old and the new metrics for the foreseeable future. These overlapping rules would provide backward compatibility while also exposing the legacy metrics on the new naming convention.

I recommend a property settable on the rule level to override the current behavior (e.g. consume which defaults to true).

[Doug Hoard]

@vbence Looking at the code...

(

jmx_exporter/collector/src/main/java/io/prometheus/jmx/JmxCollector.java

Lines 589 to 602 in 9bc7c43

 if (rule.cache) { 
     MatchedRule cachedRule = config.rulesCache.get(rule, matchName); 
     if (cachedRule != null) { 
         stalenessTracker.add(rule, matchName); 
         if (cachedRule.isMatched()) { 
             matchedRule = cachedRule; 
             break; 
         } 
  
         // The bean was cached earlier, but did not match the current rule. 
         // Skip it to avoid matching against the same pattern again 
         continue; 
     } 
 } 

)

... if cache is false (default) it looks like it should work as you expect.

Are you setting cache: true on the specific rules?