Support reading early agent config from declarative config yaml

javaagent-internal-logging-application/src/main/java/io/opentelemetry/javaagent/logging/application/ApplicationLoggingCustomizer.java

@@ -21,8 +21,7 @@ public String name() {
 
   @Override
   public void init(EarlyInitAgentConfig earlyConfig) {
-    int limit =
-        earlyConfig.getInt("otel.javaagent.logging.application.logs-buffer-max-records", 2048);
+    int limit = earlyConfig.getLoggingApplicationLogsBufferMaxRecords();
     InMemoryLogStore inMemoryLogStore = new InMemoryLogStore(limit);
     ApplicationLoggerFactory loggerFactory = new ApplicationLoggerFactory(inMemoryLogStore);
     // register a shutdown hook that'll dump the logs to stderr in case something goes wrong

javaagent-internal-logging-simple/src/main/java/io/opentelemetry/javaagent/logging/simple/Slf4jSimpleLoggingCustomizer.java

@@ -36,7 +36,7 @@ public void init(EarlyInitAgentConfig earlyConfig) {
     setSystemPropertyDefault(
         SIMPLE_LOGGER_DATE_TIME_FORMAT_PROPERTY, SIMPLE_LOGGER_DATE_TIME_FORMAT_DEFAULT);
 
-    if (earlyConfig.getBoolean("otel.javaagent.debug", false)) {
+    if (earlyConfig.getDebug()) {
       setSystemPropertyDefault(SIMPLE_LOGGER_DEFAULT_LOG_LEVEL_PROPERTY, "DEBUG");
       setSystemPropertyDefault(SIMPLE_LOGGER_PREFIX + "okhttp3.internal.http2", "INFO");
       setSystemPropertyDefault(

javaagent-tooling/src/main/java/io/opentelemetry/javaagent/tooling/AgentInstaller.java

@@ -107,7 +107,7 @@ public static void installBytebuddyAgent(
     }
 
     logVersionInfo();
-    if (earlyConfig.getBoolean(JAVAAGENT_ENABLED_CONFIG, true)) {
+    if (earlyConfig.getEnabled()) {
       List<AgentListener> agentListeners = loadOrdered(AgentListener.class, extensionClassLoader);
       installBytebuddyAgent(inst, extensionClassLoader, agentListeners, earlyConfig);
     } else {

javaagent-tooling/src/main/java/io/opentelemetry/javaagent/tooling/AgentStarterImpl.java

@@ -76,7 +76,7 @@ public void start() {
     // allows loading instrumenter customizers from agent and extensions
     ServiceLoaderUtil.setLoadFunction(clazz -> ServiceLoader.load(clazz, extensionClassLoader));
 
-    String loggerImplementationName = earlyConfig.getString("otel.javaagent.logging");
+    String loggerImplementationName = earlyConfig.getLogging();
     // default to the built-in stderr slf4j-simple logger
     if (loggerImplementationName == null) {
       loggerImplementationName = "simple";

javaagent-tooling/src/main/java/io/opentelemetry/javaagent/tooling/ExtensionClassLoader.java

@@ -62,7 +62,7 @@ public static ClassLoader getInstance(
 
     includeEmbeddedExtensionsIfFound(extensions, javaagentFile);
 
-    extensions.addAll(parseLocation(earlyConfig.getString(EXTENSIONS_CONFIG), javaagentFile));
+    extensions.addAll(parseLocation(earlyConfig.getExtensions(), javaagentFile));
 
     // TODO when logging is configured add warning about deprecated property
 

javaagent-tooling/src/main/java/io/opentelemetry/javaagent/tooling/OpenTelemetryInstaller.java

@@ -74,8 +74,8 @@ static ConfigProperties getDeclarativeConfigBridgedProperties(
         // these properties are used to initialize the SDK before the configuration file
         // is loaded for consistency, we pass them to the bridge, so that they can be read
         // later with the same value from the {@link DeclarativeConfigPropertiesBridge}
-        .addOverride("otel.javaagent.debug", earlyConfig.getBoolean("otel.javaagent.debug", false))
-        .addOverride("otel.javaagent.logging", earlyConfig.getString("otel.javaagent.logging"))
+        .addOverride("otel.javaagent.debug", earlyConfig.getDebug())
+        .addOverride("otel.javaagent.logging", earlyConfig.getLogging())
         .buildFromInstrumentationConfig(configProvider.getInstrumentationConfig());
   }
 

javaagent-tooling/src/main/java/io/opentelemetry/javaagent/tooling/config/DeclarativeConfigurationFile.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.javaagent.tooling.config;
+
+import static io.opentelemetry.api.incubator.config.DeclarativeConfigProperties.empty;
+import static java.util.logging.Level.WARNING;
+
+import io.opentelemetry.api.incubator.config.DeclarativeConfigProperties;
+import io.opentelemetry.instrumentation.api.internal.ConfigPropertiesUtil;
+import io.opentelemetry.sdk.extension.incubator.fileconfig.DeclarativeConfiguration;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.logging.Logger;
+import javax.annotation.Nullable;
+
+final class DeclarativeConfigurationFile {
+
+  static final String DECLARATIVE_CONFIG_FILE_PROPERTY = "otel.experimental.config.file";
+
+  private static DeclarativeConfigProperties configProperties;
+
+  // this class is used early, and must not use logging in most of its methods
+  // in case any file loading/parsing error occurs, we save the error message and log it later, when
+  // the logging subsystem is initialized
+  @Nullable private static String fileLoadErrorMessage;
+
+  static boolean isConfigured() {
+    String configFilePath = ConfigPropertiesUtil.getString(DECLARATIVE_CONFIG_FILE_PROPERTY);
+    return configFilePath != null && !configFilePath.isEmpty();
+  }
+
+  static DeclarativeConfigProperties getProperties() {
+    if (configProperties == null) {
+      configProperties = loadConfigFile();
+    }
+    return configProperties;
+  }
+
+  // visible for tests
+  static void resetForTest() {
+    configProperties = null;
+    fileLoadErrorMessage = null;
+  }
+
+  // visible for tests
+  static DeclarativeConfigProperties loadConfigFile() {
+    String configFilePath = ConfigPropertiesUtil.getString(DECLARATIVE_CONFIG_FILE_PROPERTY);
+    if (configFilePath == null || configFilePath.isEmpty()) {
+      return empty();
+    }
+
+    // Normalizing tilde (~) paths for unix systems
+    configFilePath = configFilePath.replaceFirst("^~", System.getProperty("user.home"));
+
+    Path file = Paths.get(configFilePath);
+    if (!Files.exists(file)) {
+      fileLoadErrorMessage = "Declarative configuration file \"" + configFilePath + "\" not found.";
+      return empty();
+    }
+
+    try (InputStream is = Files.newInputStream(file)) {
+      return DeclarativeConfiguration.toConfigProperties(is);
+    } catch (IOException e) {
+      fileLoadErrorMessage =
+          "Declarative configuration file \""
+              + configFilePath
+              + "\" cannot be accessed or correctly parsed.";
+      return empty();
+    }
+  }
+
+  static void logErrorIfAny() {
+    if (fileLoadErrorMessage != null) {
+      Logger.getLogger(DeclarativeConfigurationFile.class.getName())
+          .log(WARNING, fileLoadErrorMessage);
+    }
+  }
+
+  private DeclarativeConfigurationFile() {}
+}

javaagent-tooling/src/main/java/io/opentelemetry/javaagent/tooling/config/EarlyInitAgentConfig.java

@@ -5,6 +5,9 @@
 
 package io.opentelemetry.javaagent.tooling.config;
 
+import static io.opentelemetry.api.incubator.config.DeclarativeConfigProperties.empty;
+
+import io.opentelemetry.api.incubator.config.DeclarativeConfigProperties;
 import io.opentelemetry.instrumentation.api.internal.ConfigPropertiesUtil;
 import java.util.Map;
 import javax.annotation.Nullable;
@@ -15,33 +18,98 @@
  */
 public final class EarlyInitAgentConfig {
 
+  @Nullable private final String logging;
+  @Nullable private final String extensions;
+  private final boolean enabled;
+  private final boolean debug;
+  private final int loggingApplicationLogsBufferMaxRecords;
+  private final boolean fieldInjectionEnabled;
+
   public static EarlyInitAgentConfig create() {
+    if (DeclarativeConfigurationFile.isConfigured()) {
+      return new EarlyInitAgentConfig(DeclarativeConfigurationFile.getProperties());
+    }
     return new EarlyInitAgentConfig(ConfigurationFile.getProperties());
   }
 
-  private final Map<String, String> configFileContents;
+  private EarlyInitAgentConfig(@Nullable DeclarativeConfigProperties properties) {
+    DeclarativeConfigProperties agent =
+        (properties != null ? properties : empty())
+            .getStructured("instrumentation/development", empty())
+            .getStructured("java", empty())
+            .getStructured("agent", empty());
+
+    this.logging = agent.getString("logging");
+    this.extensions = agent.getString("extensions");
+    this.enabled = agent.getBoolean("enabled", true);
+    this.debug = agent.getBoolean("debug", false);
+    this.loggingApplicationLogsBufferMaxRecords =
+        agent
+            .getStructured("logging", empty())
+            .getStructured("application", empty())
+            .getInt("logs_buffer_max_records", 2048);
+    this.fieldInjectionEnabled =
+        agent.getStructured("field_injection/development", empty()).getBoolean("enabled", true);
+  }
 
   private EarlyInitAgentConfig(Map<String, String> configFileContents) {
-    this.configFileContents = configFileContents;
+    this.logging = loadString(configFileContents, "otel.javaagent.logging");
+    this.extensions = loadString(configFileContents, "otel.javaagent.extensions");
+    this.enabled = loadBoolean(configFileContents, "otel.javaagent.enabled", true);
+    this.debug = loadBoolean(configFileContents, "otel.javaagent.debug", false);
+    this.loggingApplicationLogsBufferMaxRecords =
+        loadInt(
+            configFileContents, "otel.javaagent.logging.application.logs-buffer-max-records", 2048);
+    this.fieldInjectionEnabled =
+        loadBoolean(
+            configFileContents, "otel.javaagent.experimental.field-injection.enabled", true);
+  }
+
+  @Nullable
+  public String getLogging() {
+    return logging;
+  }
+
+  @Nullable
+  public String getExtensions() {
+    return extensions;
+  }
+
+  public boolean getEnabled() {
+    return enabled;
+  }
+
+  public boolean getDebug() {
+    return debug;
+  }
+
+  public int getLoggingApplicationLogsBufferMaxRecords() {
+    return loggingApplicationLogsBufferMaxRecords;
+  }
+
+  public boolean getFieldInjectionEnabled() {
+    return fieldInjectionEnabled;
   }
 
   @Nullable
-  public String getString(String propertyName) {
+  private static String loadString(Map<String, String> configFileContents, String propertyName) {
     String value = ConfigPropertiesUtil.getString(propertyName);
     if (value != null) {
       return value;
     }
     return configFileContents.get(propertyName);
   }
 
-  public boolean getBoolean(String propertyName, boolean defaultValue) {
+  private static boolean loadBoolean(
+      Map<String, String> configFileContents, String propertyName, boolean defaultValue) {
     String configFileValueStr = configFileContents.get(propertyName);
     boolean configFileValue =
         configFileValueStr == null ? defaultValue : Boolean.parseBoolean(configFileValueStr);
     return ConfigPropertiesUtil.getBoolean(propertyName, configFileValue);
   }
 
-  public int getInt(String propertyName, int defaultValue) {
+  private static int loadInt(
+      Map<String, String> configFileContents, String propertyName, int defaultValue) {
     try {
       String configFileValueStr = configFileContents.get(propertyName);
       int configFileValue =
@@ -54,5 +122,6 @@ public int getInt(String propertyName, int defaultValue) {
 
   public void logEarlyConfigErrorsIfAny() {
     ConfigurationFile.logErrorIfAny();
+    DeclarativeConfigurationFile.logErrorIfAny();
   }
 }

javaagent-tooling/src/main/java/io/opentelemetry/javaagent/tooling/field/FieldBackedImplementationConfiguration.java

@@ -11,8 +11,7 @@ public final class FieldBackedImplementationConfiguration {
   static boolean fieldInjectionEnabled = true;
 
   public static void configure(EarlyInitAgentConfig config) {
-    fieldInjectionEnabled =
-        config.getBoolean("otel.javaagent.experimental.field-injection.enabled", true);
+    fieldInjectionEnabled = config.getFieldInjectionEnabled();
   }
 
   private FieldBackedImplementationConfiguration() {}