fix: Fixed jar shading (#1554)

Signed-off-by: dhoard <doug.hoard@gmail.com>

Author: dhoard

collector/src/main/java/io/prometheus/jmx/JmxScraper.java

@@ -689,17 +689,39 @@ public void recordBean(
                 String attrType,
                 String attrDescription,
                 Object value) {
-            System.out.println(new StringBuilder(256)
+            System.out.println(escapeControlCharacters(new StringBuilder(256)
                     .append(domain)
                     .append(beanProperties)
                     .append(attrKeys)
                     .append(attrName)
                     .append(": ")
                     .append(value)
-                    .toString());
+                    .toString()));
         }
     }
 
+    /**
+     * Escapes every C0 control character (U+0000-U+001F) and DEL (U+007F) in
+     * {@code value} as a two-digit lowercase hexadecimal escape (for example
+     * {@code \x01}), so the resulting string is plain text. All other
+     * characters are returned unchanged.
+     *
+     * @param value the string to escape
+     * @return the escaped string
+     */
+    private static String escapeControlCharacters(String value) {
+        StringBuilder escaped = new StringBuilder(value.length());
+        for (int i = 0; i < value.length(); i++) {
+            char c = value.charAt(i);
+            if (c < 0x20 || c == 0x7f) {
+                escaped.append('\\').append('x').append(String.format("%02x", (int) c));
+            } else {
+                escaped.append(c);
+            }
+        }
+        return escaped.toString();
+    }
+
     /**
      * Convenience method to run standalone.
      */

collector/src/test/java/io/prometheus/jmx/JmxScraperTest.java

@@ -502,6 +502,37 @@ void stdoutWriterRecordsBeanToStdout() {
                 System.setOut(originalOut);
             }
         }
+
+        @Test
+        void stdoutWriterEscapesControlCharactersInOutput() {
+            ByteArrayOutputStream baos = new ByteArrayOutputStream();
+            PrintStream originalOut = System.out;
+            System.setOut(new PrintStream(baos, true));
+            try {
+                JmxScraper.MBeanReceiver stdoutWriter = createStdoutWriter();
+
+                LinkedHashMap<String, String> beanProperties = new LinkedHashMap<>();
+                beanProperties.put("type", "Colliding\u0001Name");
+                List<String> attrKeys = new ArrayList<>();
+                attrKeys.add("key1");
+
+                stdoutWriter.recordBean(
+                        "test.domain",
+                        beanProperties,
+                        Collections.emptyMap(),
+                        attrKeys,
+                        "AttrName",
+                        "java.lang.String",
+                        "desc",
+                        "hello");
+
+                String output = baos.toString();
+                assertThat(output).contains("Colliding\\x01Name");
+                assertThat(output).doesNotContain("Colliding\u0001Name");
+            } finally {
+                System.setOut(originalOut);
+            }
+        }
     }
 
     @Nested

jmx_prometheus_common/src/main/java/io/prometheus/jmx/common/tools/CustomServiceTransformer.java

@@ -25,6 +25,7 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.jar.JarEntry;
 import java.util.jar.JarOutputStream;
 import org.apache.maven.plugins.shade.relocation.Relocator;
@@ -37,22 +38,32 @@
  * and entries. This is used during shading to prevent conflicts between the shaded and unshaded
  * versions of the same library.
  *
- * <p>The prefix {@code e1723a08afd7bca35570fd31a7656f59.} is added to:
+ * <p>A unique shading prefix is added to:
  *
  * <ul>
  *   <li>Service file names (e.g., META-INF/services/MyService becomes
- *       META-INF/services/e1723a08afd7bca35570fd31a7656f59.MyService)
+ *       META-INF/services/{@code <prefix>}MyService)
  *   <li>Service implementation class names within the files
  * </ul>
  *
+ * <p>The prefix is configured by the Maven Shade plugin via the {@code <prefix>}
+ * element; it is generated at build time so that each build uses a fresh
+ * namespace. The default prefix is retained for backwards compatibility when
+ * no prefix is configured.
+ *
  * <p>This class is used during the Maven build process and is not used at runtime.
  */
 public class CustomServiceTransformer implements ResourceTransformer {
 
+    /**
+     * Default prefix to add to service names and entries when none is configured.
+     */
+    private static final String DEFAULT_PREFIX = "e1723a08afd7bca35570fd31a7656f59.";
+
     /**
      * Prefix to add to service names and entries.
      */
-    private static final String PREFIX = "e1723a08afd7bca35570fd31a7656f59.";
+    private String prefix = DEFAULT_PREFIX;
 
     /**
      * META-INF services directory path.
@@ -73,6 +84,15 @@ public CustomServiceTransformer() {
         // Intentionally empty
     }
 
+    /**
+     * Sets the prefix to add to service names and entries.
+     *
+     * @param prefix the prefix to add, must not be {@code null}
+     */
+    public void setPrefix(String prefix) {
+        this.prefix = Objects.requireNonNull(prefix);
+    }
+
     /**
      * Determines whether the resource is a META-INF/services file that should be transformed.
      *
@@ -105,7 +125,7 @@ public void processResource(String resource, InputStream is, List<Relocator> rel
                     .filter(line -> !line.isEmpty())
                     .map(line -> {
                         // Avoid double prefixing
-                        return line.startsWith(PREFIX) ? line : PREFIX + line;
+                        return line.startsWith(prefix) ? line : prefix + line;
                     })
                     .forEach(line -> {
                         if (!entries.contains(line)) {
@@ -129,7 +149,7 @@ public boolean hasTransformedResource() {
      * Writes the collected service entries to the JAR with prefixed filenames and entries.
      *
      * <p>Each service file is written to a new path where the service name is prefixed with
-     * {@value #PREFIX}, and all implementation class entries within the file are also prefixed.
+     * {@link #prefix}, and all implementation class entries within the file are also prefixed.
      *
      * @param jos the JAR output stream to write to
      * @throws IOException if writing to the JAR fails
@@ -140,7 +160,7 @@ public void modifyOutputStream(JarOutputStream jos) throws IOException {
             String originalPath = entry.getKey();
             List<String> lines = entry.getValue();
 
-            String newPath = SERVICES_DIR + PREFIX + originalPath.substring(SERVICES_DIR.length());
+            String newPath = SERVICES_DIR + prefix + originalPath.substring(SERVICES_DIR.length());
 
             jos.putNextEntry(new JarEntry(newPath));
             for (String line : lines) {

jmx_prometheus_common/src/test/java/io/prometheus/jmx/common/tools/CustomServiceTransformerTest.java

@@ -24,6 +24,9 @@
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.List;
+import java.util.jar.JarEntry;
+import java.util.jar.JarInputStream;
 import java.util.jar.JarOutputStream;
 import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
@@ -165,6 +168,31 @@ void modifyOutputStreamWritesPrefixedServiceName() throws IOException {
             assertThat(baos.toByteArray().length).isGreaterThan(0);
         }
 
+        @Test
+        void modifyOutputStreamUsesConfiguredPrefix() throws IOException {
+            CustomServiceTransformer transformer = new CustomServiceTransformer();
+            transformer.setPrefix("ab12cd34.");
+            byte[] content = "com.example.Impl1\n".getBytes(StandardCharsets.UTF_8);
+            transformer.processResource(
+                    "META-INF/services/com.example.MyService",
+                    new ByteArrayInputStream(content),
+                    Collections.emptyList());
+
+            ByteArrayOutputStream baos = new ByteArrayOutputStream();
+            try (JarOutputStream jos = new JarOutputStream(baos)) {
+                transformer.modifyOutputStream(jos);
+            }
+
+            try (JarInputStream jis = new JarInputStream(new ByteArrayInputStream(baos.toByteArray()))) {
+                List<String> names = new ArrayList<>();
+                JarEntry jarEntry;
+                while ((jarEntry = jis.getNextJarEntry()) != null) {
+                    names.add(jarEntry.getName());
+                }
+                assertThat(names).containsExactly("META-INF/services/ab12cd34.com.example.MyService");
+            }
+        }
+
         @Test
         void modifyOutputStreamWritesMultipleServices() throws IOException {
             CustomServiceTransformer transformer = new CustomServiceTransformer();

jmx_prometheus_isolator_javaagent/pom.xml

@@ -60,6 +60,18 @@
                                     <exclude>org.vafer:jdependency</exclude>
                                 </excludes>
                             </artifactSet>
+                            <relocations>
+                                <relocation>
+                                    <shadedPattern>${isolator.shade.prefix}.</shadedPattern>
+                                    <includes>
+                                        <include>io.prometheus.jmx.**</include>
+                                    </includes>
+                                    <excludes>
+                                        <exclude>io.prometheus.jmx.IsolatorJavaAgent</exclude>
+                                        <exclude>io.prometheus.jmx.JavaAgent</exclude>
+                                    </excludes>
+                                </relocation>
+                            </relocations>
                             <transformers>
                                 <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                                     <manifestEntries>

jmx_prometheus_isolator_javaagent/src/main/java/io/prometheus/jmx/JarClassLoader.java

@@ -20,7 +20,9 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Map;
+import java.util.Set;
 import java.util.jar.Attributes;
 import java.util.jar.JarEntry;
 import java.util.jar.JarFile;
@@ -51,11 +53,11 @@
  *   <li>Fall back to the standard parent-first chain ({@code super.loadClass()})
  * </ol>
  *
- * <p>Each exporter JAR is fully shaded under the
- * {@code e1723a08afd7bca35570fd31a7656f59.} prefix, so all dependency classes are
- * namespace-scoped to that JAR. The self-first strategy ensures the exact version packaged
- * inside each JAR is used, preventing {@link ClassCastException} and other version conflicts
- * when multiple exporter instances run in the same JVM.
+ * <p>Each exporter JAR is fully shaded under a unique build-time prefix, so all
+ * dependency classes are namespace-scoped to that JAR. The self-first strategy
+ * ensures the exact version packaged inside each JAR is used, preventing
+ * {@link ClassCastException} and other version conflicts when multiple exporter
+ * instances run in the same JVM.
  *
  * <p>Thread-safety: This class is thread-safe. Class loading operations are synchronized by
  * the parent ClassLoader.
@@ -87,6 +89,11 @@ public class JarClassLoader extends ClassLoader {
      */
     private final Map<String, byte[]> classBytes = new HashMap<>();
 
+    /**
+     * Package names already defined by this classloader.
+     */
+    private final Set<String> definedPackages = new HashSet<>();
+
     /**
      * Constructs a classloader that loads classes from the specified JAR file.
      *
@@ -222,25 +229,28 @@ private byte[] readAllBytes(InputStream inputStream) throws IOException {
     /**
      * Ensures that the package for a class is defined before loading.
      *
-     * <p>For classes with the shading prefix, the package is defined with implementation
-     * title and version from the JAR manifest.
+     * <p>Packages are defined with the implementation title and version from the JAR
+     * manifest. Only packages defined by this classloader are considered, so packages
+     * defined by a parent classloader (including packages of the same name defined for
+     * classes loaded from the system classpath) do not prevent the package metadata from
+     * being attached here.
      *
      * @param className the fully qualified class name
      */
     private void ensurePackageDefined(String className) {
         int index = className.lastIndexOf('.');
         if (index != -1) {
             String packageName = className.substring(0, index);
-            if (getPackage(packageName) == null) {
-                String title = null;
-                String version = null;
-
-                if (className.startsWith("e1723a08afd7bca35570fd31a7656f59")) {
-                    title = manifestMap.get(IMPLEMENTATION_TITLE);
-                    version = manifestMap.get(IMPLEMENTATION_VERSION);
-                }
-
-                definePackage(packageName, null, null, null, title, version, null, null);
+            if (definedPackages.add(packageName)) {
+                definePackage(
+                        packageName,
+                        null,
+                        null,
+                        null,
+                        manifestMap.get(IMPLEMENTATION_TITLE),
+                        manifestMap.get(IMPLEMENTATION_VERSION),
+                        null,
+                        null);
             }
         }
     }

jmx_prometheus_javaagent/pom.xml

@@ -106,7 +106,7 @@
                             </filters>
                             <relocations>
                                 <relocation>
-                                    <shadedPattern>e1723a08afd7bca35570fd31a7656f59.</shadedPattern>
+                                    <shadedPattern>${exporter.shade.prefix}.</shadedPattern>
                                     <includes>
                                         <include>com.**</include>
                                         <include>google.**</include>
@@ -125,7 +125,7 @@
                                 </relocation>
                                 <relocation>
                                     <pattern>io.prometheus.metrics.shaded</pattern>
-                                    <shadedPattern>e1723a08afd7bca35570fd31a7656f59.io.prometheus.metrics.shaded</shadedPattern>
+                                    <shadedPattern>${exporter.shade.prefix}.io.prometheus.metrics.shaded</shadedPattern>
                                 </relocation>
                             </relocations>
                             <transformers>
@@ -137,7 +137,9 @@
                                         <Implementation-Title>${project.artifactId}</Implementation-Title>
                                     </manifestEntries>
                                 </transformer>
-                                <transformer implementation="io.prometheus.jmx.common.tools.CustomServiceTransformer"/>
+                                <transformer implementation="io.prometheus.jmx.common.tools.CustomServiceTransformer">
+                                    <prefix>${exporter.shade.prefix}.</prefix>
+                                </transformer>
                             </transformers>
                         </configuration>
                     </execution>

jmx_prometheus_standalone/pom.xml

@@ -111,7 +111,7 @@
                             </filters>
                             <relocations>
                                 <relocation>
-                                    <shadedPattern>e1723a08afd7bca35570fd31a7656f59.</shadedPattern>
+                                    <shadedPattern>${exporter.shade.prefix}.</shadedPattern>
                                     <includes>
                                         <include>com.**</include>
                                         <include>google.**</include>
@@ -129,7 +129,7 @@
                                 </relocation>
                                 <relocation>
                                     <pattern>io.prometheus.metrics.shaded</pattern>
-                                    <shadedPattern>e1723a08afd7bca35570fd31a7656f59.io.prometheus.metrics.shaded</shadedPattern>
+                                    <shadedPattern>${exporter.shade.prefix}.io.prometheus.metrics.shaded</shadedPattern>
                                 </relocation>
                             </relocations>
                             <transformers>
@@ -140,7 +140,9 @@
                                         <Implementation-Title>${project.artifactId}</Implementation-Title>
                                     </manifestEntries>
                                 </transformer>
-                                <transformer implementation="io.prometheus.jmx.common.tools.CustomServiceTransformer"/>
+                                <transformer implementation="io.prometheus.jmx.common.tools.CustomServiceTransformer">
+                                    <prefix>${exporter.shade.prefix}.</prefix>
+                                </transformer>
                             </transformers>
                         </configuration>
                     </execution>