Migrate from snakeyaml to snakeyaml-engine (#554)

The main motivation is to get rid of using snakeyaml reflection, which is poorly compatible with GraalVM native builds.
snakeyaml-engine is a slimmer version of snakeyaml, but without support for JavaBeans that rely heavily on reflection.

Author: ygree

pom.xml

@@ -61,7 +61,7 @@
         <lombok.version>1.18.32</lombok.version>
         <mockito.version>2.28.2</mockito.version>
         <slf4j.version>1.7.32</slf4j.version>
-        <snakeyaml.version>2.0</snakeyaml.version>
+        <snakeyaml-engine.version>2.9</snakeyaml-engine.version>
         <testcontainers.version>1.19.8</testcontainers.version>
 
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
@@ -186,9 +186,9 @@
             <version>${slf4j.version}</version>
         </dependency>
         <dependency>
-            <groupId>org.yaml</groupId>
-            <artifactId>snakeyaml</artifactId>
-            <version>${snakeyaml.version}</version>
+            <groupId>org.snakeyaml</groupId>
+            <artifactId>snakeyaml-engine</artifactId>
+            <version>${snakeyaml-engine.version}</version>
         </dependency>
         <dependency>
             <groupId>javax.management.j2ee</groupId>

src/main/java/org/datadog/jmxfetch/Instance.java

@@ -5,9 +5,8 @@
 import org.datadog.jmxfetch.service.ConfigServiceNameProvider;
 import org.datadog.jmxfetch.service.ServiceNameProvider;
 import org.datadog.jmxfetch.util.InstanceTelemetry;
-import org.yaml.snakeyaml.Yaml;
-
-
+import org.snakeyaml.engine.v2.api.Load;
+import org.snakeyaml.engine.v2.api.LoadSettings;
 
 import java.io.File;
 import java.io.FileInputStream;
@@ -43,11 +42,12 @@ public class Instance {
     public static final String JVM_DIRECT = "jvm_direct";
     public static final String ATTRIBUTE = "Attribute: ";
 
-    private static final ThreadLocal<Yaml> YAML =
-        new ThreadLocal<Yaml>() {
+    private static final ThreadLocal<Load> YAML =
+        new ThreadLocal<Load>() {
             @Override
-            public Yaml initialValue() {
-                return new Yaml();
+            public Load initialValue() {
+                LoadSettings settings = LoadSettings.builder().build();
+                return new Load(settings);
             }
         };
 
@@ -295,9 +295,9 @@ public static boolean isDirectInstance(Map<String, Object> configInstance) {
     }
 
     private void loadDefaultConfig(String configResourcePath) {
-        List<Map<String, Object>> defaultConf =
-                (List<Map<String, Object>>)
-                        YAML.get().load(this.getClass().getResourceAsStream(configResourcePath));
+        InputStream is = this.getClass().getResourceAsStream(configResourcePath);
+        List<Map<String, Object>> defaultConf = (List<Map<String, Object>>)
+                YAML.get().loadFromInputStream(is);
         for (Map<String, Object> conf : defaultConf) {
             configurationList.add(new Configuration(conf));
         }
@@ -321,7 +321,7 @@ static void loadMetricConfigFiles(
                     yamlInputStream = new FileInputStream(yamlPath);
                     List<Map<String, Object>> confs =
                             (List<Map<String, Object>>)
-                                    YAML.get().load(yamlInputStream);
+                                    YAML.get().loadFromInputStream(yamlInputStream);
                     for (Map<String, Object> conf : confs) {
                         configurationList.add(new Configuration(conf));
                     }
@@ -360,7 +360,7 @@ static void loadMetricConfigResources(
                     try {
                         Map<String, List<Map<String, Object>>> topYaml =
                                 (Map<String, List<Map<String, Object>>>)
-                                        YAML.get().load(inputStream);
+                                        YAML.get().loadFromInputStream(inputStream);
                         List<Map<String, Object>> jmxConf =
                                 topYaml.get("jmx_metrics");
                         if (jmxConf != null) {

src/main/java/org/datadog/jmxfetch/Status.java

@@ -5,7 +5,8 @@
 
 import org.datadog.jmxfetch.util.InstanceTelemetry;
 import org.datadog.jmxfetch.util.MetadataHelper;
-import org.yaml.snakeyaml.Yaml;
+import org.snakeyaml.engine.v2.api.Dump;
+import org.snakeyaml.engine.v2.api.DumpSettings;
 
 import java.io.BufferedOutputStream;
 import java.io.File;
@@ -147,16 +148,17 @@ public void addInitFailedCheck(String checkName, String message, String status)
     }
 
     private String generateYaml() {
-        Map<String, Object> status = new HashMap<String, Object>();
+        Map<String, Object> status = new HashMap<>();
         status.put("info", this.info);
         status.put("timestamp", System.currentTimeMillis());
         status.put("checks", this.instanceStats);
         status.put("errors", this.errors);
-        return new Yaml().dump(status);
+        DumpSettings settings = DumpSettings.builder().build();
+        return new Dump(settings).dumpToString(status);
     }
 
     private String generateJson() throws IOException {
-        Map<String, Object> status = new HashMap<String, Object>();
+        Map<String, Object> status = new HashMap<>();
         status.put("info", this.info);
         status.put("timestamp", System.currentTimeMillis());
         status.put("checks", this.instanceStats);

src/main/java/org/datadog/jmxfetch/YamlParser.java

@@ -1,22 +1,18 @@
 package org.datadog.jmxfetch;
 
-import org.yaml.snakeyaml.Yaml;
+import org.snakeyaml.engine.v2.api.Load;
+import org.snakeyaml.engine.v2.api.LoadSettings;
 
 import java.io.InputStream;
-import java.util.HashMap;
 import java.util.Map;
 
-@SuppressWarnings("unchecked")
 class YamlParser {
 
-    private Map<Object, Object> parsedYaml;
+    private final Map<Object, Object> parsedYaml;
 
     public YamlParser(InputStream yamlInputStream) {
-        parsedYaml = (Map<Object, Object>) new Yaml().load(yamlInputStream);
-    }
-
-    public YamlParser(YamlParser other) {
-        parsedYaml = new HashMap<Object, Object>((Map<Object, Object>) other.getParsedYaml());
+        LoadSettings settings = LoadSettings.builder().build();
+        parsedYaml = (Map<Object, Object>) new Load(settings).loadFromInputStream(yamlInputStream);
     }
 
     public Object getYamlInstances() {
@@ -26,8 +22,4 @@ public Object getYamlInstances() {
     public Object getInitConfig() {
         return parsedYaml.get("init_config");
     }
-
-    public Object getParsedYaml() {
-        return parsedYaml;
-    }
 }

src/test/java/org/datadog/jmxfetch/StatusTest.java

@@ -6,15 +6,15 @@
 import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.InputStream;
-import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
 import org.datadog.jmxfetch.util.InstanceTelemetry;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.TemporaryFolder;
-import org.yaml.snakeyaml.Yaml;
+import org.snakeyaml.engine.v2.api.Load;
+import org.snakeyaml.engine.v2.api.LoadSettings;
 
 public class StatusTest {
 
@@ -45,12 +45,13 @@ public void TestStatus() throws IOException {
         status.addInstanceStats("fake_check", "fake_instance", 10, 3, "fake_message", Status.STATUS_OK, instance);
         status.flush();
 
-        Yaml yaml = new Yaml();
+        LoadSettings settings = LoadSettings.builder().build(); //TODO
+        Load load = new Load(settings);
         InputStream inputStream = new FileInputStream(tempFilePath);
 
-        HashMap yamlMap = yaml.load(inputStream);
-        HashMap checks = (HashMap) yamlMap.get("checks");
-        HashMap initializedChecks = (HashMap) checks.get("initialized_checks");
+        Map<?, ?> yamlMap = (Map<?, ?>) load.loadFromInputStream(inputStream);
+        Map<?, ?> checks = (Map<?, ?>) yamlMap.get("checks");
+        Map<?, ?> initializedChecks = (Map<?, ?>) checks.get("initialized_checks");
         List<Map<String, Object>> fakeCheck = (List<Map<String, Object>>) initializedChecks.get("fake_check");
         Map<String, Object> stats = fakeCheck.get(0);
         assertEquals("fake_instance", stats.get("instance_name"));