Initial commit

* Add Stable config source
* Add snakeyaml to parse file

internal-api/build.gradle

@@ -218,6 +218,8 @@ dependencies {
   // it contains annotations that are also present in the instrumented application classes
   api "com.datadoghq:dd-javac-plugin-client:0.2.2"
 
+  implementation 'org.yaml:snakeyaml:2.0'
+
   testImplementation project(":utils:test-utils")
   testImplementation("org.assertj:assertj-core:3.20.2")
   testImplementation libs.bundles.junit5

internal-api/src/main/java/datadog/trace/api/ConfigOrigin.java

@@ -7,6 +7,10 @@ public enum ConfigOrigin {
   REMOTE("remote_config"),
   /** configurations that are set through JVM properties */
   JVM_PROP("jvm_prop"),
+  /** configuration read in the stable config file, managed by customers */
+  CUSTOMER_STABLE_CONFIG("customer_stable_config"),
+  /** configuration read in the stable config file, managed by fleet */
+  FLEET_STABLE_CONFIG("fleet_stable_config"),
   /** set when the user has not set any configuration for the key (defaults to a value) */
   DEFAULT("default");
 

internal-api/src/main/java/datadog/trace/bootstrap/config/provider/StableConfigSource.java

@@ -0,0 +1,63 @@
+package datadog.trace.bootstrap.config.provider;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.InputStream;
+import java.util.HashMap;
+
+import static datadog.trace.util.Strings.propertyNameToEnvironmentVariableName;
+
+import datadog.trace.api.ConfigOrigin;
+import datadog.trace.bootstrap.config.provider.ConfigProvider;
+
+import org.yaml.snakeyaml.Yaml;
+import org.yaml.snakeyaml.LoaderOptions;
+import org.yaml.snakeyaml.constructor.SafeConstructor;
+
+final public class StableConfigSource extends ConfigProvider.Source {
+  static final String MANAGED_STABLE_CONFIGURATION_PATH = "/etc/datadog-agent/managed/datadog-agent/stable/datadog_apm.yaml";
+  static final String LOCAL_STABLE_CONFIGURATION_PATH = "/etc/datadog-agent/datadog_apm.yaml";
+
+  final ConfigOrigin fileOrigin;
+  HashMap<String, String> configuration;
+
+  StableConfigSource(String file, ConfigOrigin origin) {
+    this.fileOrigin = origin;
+    try {
+      configuration = parseStableConfig(file);
+    } catch (Exception e) {
+      configuration = new HashMap();
+    }
+  }
+
+  private static final HashMap<String, String> parseStableConfig(String filePath) {
+    Yaml yaml = new Yaml(new SafeConstructor(new LoaderOptions()));
+    InputStream input = new FileInputStream(new File(filePath));
+    Object data = yaml.load(input);
+
+    HashMap<Sting, Object> config = new HashMap();
+
+    return config; 
+  };
+
+  public final String get(String key) {
+    return configuration.get(propertyNameToEnvironmentVariableName(key));
+  }
+
+  public final ConfigOrigin origin() {
+    return fileOrigin;
+  }
+
+  private class StableConfig {
+    private String config_id;
+    private HashMap<String, Object> apm_configuration_default;
+
+    private void setApmConfigurationDefault(HashMap<String, Object> m) {
+      apm_configuration_default = m;
+    }
+
+    private void setConfigId(String i) {
+      config_id = i;
+    }
+  }
+}