From 17ec981881a6dde56588516a5bce5c9c61dfa806 Mon Sep 17 00:00:00 2001
From: Csaba Karsai <csaba.karsai@emnify.com>
Date: Thu, 8 Jul 2021 10:17:41 +0200
Subject: [PATCH] added beanshell support for value field

Signed-off-by: Csaba Karsai <csaba.karsai@emnify.com>
---
 collector/pom.xml                             |  5 ++++
 .../java/io/prometheus/jmx/JmxCollector.java  | 23 +++++++++++++++----
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/collector/pom.xml b/collector/pom.xml
index af16826c..012213ab 100644
--- a/collector/pom.xml
+++ b/collector/pom.xml
@@ -19,6 +19,11 @@
       <groupId>io.prometheus</groupId>
       <artifactId>simpleclient</artifactId>
     </dependency>
+    <dependency>
+      <groupId>org.beanshell</groupId>
+      <artifactId>bsh-core</artifactId>
+      <version>2.0b4</version>
+    </dependency>
     <dependency>
       <groupId>junit</groupId>
       <artifactId>junit</artifactId>
diff --git a/collector/src/main/java/io/prometheus/jmx/JmxCollector.java b/collector/src/main/java/io/prometheus/jmx/JmxCollector.java
index 7758bd5f..78dd17b3 100644
--- a/collector/src/main/java/io/prometheus/jmx/JmxCollector.java
+++ b/collector/src/main/java/io/prometheus/jmx/JmxCollector.java
@@ -1,5 +1,7 @@
 package io.prometheus.jmx;
 
+import bsh.EvalError;
+import bsh.Interpreter;
 import io.prometheus.client.Collector;
 import io.prometheus.client.Counter;
 import org.yaml.snakeyaml.Yaml;
@@ -444,11 +446,9 @@ public void recordBean(
 
           Double value = null;
           if (rule.value != null && !rule.value.isEmpty()) {
-            String val = matcher.replaceAll(rule.value);
             try {
-              value = Double.valueOf(val);
-            } catch (NumberFormatException e) {
-              LOGGER.fine("Unable to parse configured value '" + val + "' to number for bean: " + beanName + attrName + ": " + beanValue);
+              value = evaluateValueExpression(matcher, rule.value);
+            } catch (RuntimeException e) {
               return;
             }
           }
@@ -528,6 +528,21 @@ public void recordBean(
 
     }
 
+    private Double evaluateValueExpression(Matcher matcher, String value) {
+        try {
+            Interpreter interpreter = new Interpreter();
+            List<String> groups = new ArrayList<String>(matcher.groupCount());
+            for(int i=0; i<=matcher.groupCount(); i++) {
+                groups.add(matcher.group(i));
+            }
+            interpreter.set("matches", groups);
+            return Double.valueOf(interpreter.eval(matcher.replaceAll(value)).toString());
+        } catch (EvalError e) {
+            LOGGER.fine(e.toString());
+            throw new RuntimeException(e);
+        }
+    }
+
   public List<MetricFamilySamples> collect() {
       // Take a reference to the current config and collect with this one
       // (to avoid race conditions in case another thread reloads the config in the meantime)