[dynamic control] Add pipeline config initialization from file

dynamic-control/src/main/java/io/opentelemetry/contrib/dynamic/policy/registry/PolicyInitConfig.java

@@ -5,13 +5,28 @@
 
 package io.opentelemetry.contrib.dynamic.policy.registry;
 
+import io.opentelemetry.contrib.dynamic.policy.registry.json.JsonPolicyInitConfigReader;
+import io.opentelemetry.contrib.dynamic.policy.registry.yaml.YamlPolicyInitConfigReader;
+import io.opentelemetry.sdk.autoconfigure.spi.ConfigProperties;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.Files;
+import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+import javax.annotation.Nullable;
 
 /** Top-level registry initialization model containing per-source mapping config. */
 public final class PolicyInitConfig {
+  static final String POLICY_INIT_CONFIG_PROPERTY_JSON =
+      "otel.java.experimental.telemetry.policy.init.json";
+  static final String POLICY_INIT_CONFIG_PROPERTY_YAML =
+      "otel.java.experimental.telemetry.policy.init.yaml";
+  private static final Logger logger = Logger.getLogger(PolicyInitConfig.class.getName());
 
   private final List<PolicySourceConfig> sources;
 
@@ -28,6 +43,52 @@ public List<PolicySourceConfig> getSources() {
     return sources;
   }
 
+  /**
+   * Reads policy-init configuration based on config properties.
+   *
+   * <p>YAML takes precedence over JSON when both are present. If both are present, and the YAML
+   * file is invalid, the JSON file is still ignored. If the file parsed is invalid, a warning is
+   * logged and null is returned.
+   *
+   * @param config OpenTelemetry config properties
+   * @return parsed init config, or null when no init-config path is configured or the file is
+   *     invalid
+   * @throws NullPointerException if config is null
+   */
+  @Nullable
+  public static PolicyInitConfig readFromConfigProperties(ConfigProperties config) {
+    Objects.requireNonNull(config, "config cannot be null");
+    String mappingPathYaml = config.getString(POLICY_INIT_CONFIG_PROPERTY_YAML);
+    if (mappingPathYaml == null || mappingPathYaml.trim().isEmpty()) {
+      String mappingPathJson = config.getString(POLICY_INIT_CONFIG_PROPERTY_JSON);
+      if (mappingPathJson == null || mappingPathJson.trim().isEmpty()) {
+        return null;
+      } else {
+        try (InputStream in = Files.newInputStream(Paths.get(mappingPathJson.trim()))) {
+          return JsonPolicyInitConfigReader.read(in);
+        } catch (IOException | RuntimeException e) {
+          logger.log(
+              Level.WARNING,
+              "Failed to load telemetry policy init config from {0}",
+              mappingPathJson.trim());
+          logger.log(Level.WARNING, "Policy init config read failed", e);
+          return null;
+        }
+      }
+    } else {
+      try (InputStream in = Files.newInputStream(Paths.get(mappingPathYaml.trim()))) {
+        return YamlPolicyInitConfigReader.read(in);
+      } catch (IOException | RuntimeException e) {
+        logger.log(
+            Level.WARNING,
+            "Failed to load telemetry policy init config from {0}",
+            mappingPathYaml.trim());
+        logger.log(Level.WARNING, "Policy init config read failed", e);
+        return null;
+      }
+    }
+  }
+
   @Override
   public boolean equals(Object obj) {
     if (this == obj) {

dynamic-control/src/test/java/io/opentelemetry/contrib/dynamic/policy/registry/PolicyInitConfigTest.java

@@ -0,0 +1,156 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.contrib.dynamic.policy.registry;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import io.opentelemetry.contrib.dynamic.policy.source.SourceFormat;
+import io.opentelemetry.contrib.dynamic.policy.source.SourceKind;
+import io.opentelemetry.sdk.autoconfigure.spi.ConfigProperties;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+class PolicyInitConfigTest {
+
+  @TempDir Path tempDir;
+
+  @Test
+  void readFromConfigPropertiesReturnsNullWhenBothPathsMissing() {
+    ConfigProperties config = mock(ConfigProperties.class);
+    when(config.getString(PolicyInitConfig.POLICY_INIT_CONFIG_PROPERTY_YAML)).thenReturn(null);
+    when(config.getString(PolicyInitConfig.POLICY_INIT_CONFIG_PROPERTY_JSON)).thenReturn(null);
+
+    assertThat(PolicyInitConfig.readFromConfigProperties(config)).isNull();
+  }
+
+  @Test
+  void readFromConfigPropertiesPrefersYamlWhenBothPathsPresent() throws Exception {
+    Path jsonPath = tempDir.resolve("policy-init.json");
+    Files.write(jsonPath, jsonWithLocation("from-json").getBytes(StandardCharsets.UTF_8));
+    Path yamlPath = tempDir.resolve("policy-init.yaml");
+    Files.write(yamlPath, yamlWithLocation("from-yaml").getBytes(StandardCharsets.UTF_8));
+
+    ConfigProperties config = mock(ConfigProperties.class);
+    when(config.getString(PolicyInitConfig.POLICY_INIT_CONFIG_PROPERTY_YAML))
+        .thenReturn(yamlPath.toString());
+    when(config.getString(PolicyInitConfig.POLICY_INIT_CONFIG_PROPERTY_JSON))
+        .thenReturn(jsonPath.toString());
+
+    PolicyInitConfig initConfig = PolicyInitConfig.readFromConfigProperties(config);
+
+    assertThat(initConfig).isNotNull();
+    assertThat(initConfig.getSources()).hasSize(1);
+    assertThat(initConfig.getSources().get(0).getLocation()).isEqualTo("from-yaml");
+  }
+
+  @Test
+  void readFromConfigPropertiesFallsBackToJsonWhenYamlBlank() throws Exception {
+    Path jsonPath = tempDir.resolve("policy-init.json");
+    Files.write(jsonPath, jsonWithLocation("from-json").getBytes(StandardCharsets.UTF_8));
+
+    ConfigProperties config = mock(ConfigProperties.class);
+    when(config.getString(PolicyInitConfig.POLICY_INIT_CONFIG_PROPERTY_YAML)).thenReturn("  ");
+    when(config.getString(PolicyInitConfig.POLICY_INIT_CONFIG_PROPERTY_JSON))
+        .thenReturn(jsonPath.toString());
+
+    PolicyInitConfig initConfig = PolicyInitConfig.readFromConfigProperties(config);
+
+    assertThat(initConfig).isNotNull();
+    assertThat(initConfig.getSources()).hasSize(1);
+    assertThat(initConfig.getSources().get(0).getLocation()).isEqualTo("from-json");
+  }
+
+  @Test
+  void readFromConfigPropertiesReadsJsonWhenYamlPathMissing() throws Exception {
+    Path configPath = tempDir.resolve("policy-init.json");
+    Files.write(configPath, minimalJsonConfig().getBytes(StandardCharsets.UTF_8));
+
+    PolicyInitConfig config = configFromPaths(null, configPath.toString());
+
+    assertThat(config.getSources()).hasSize(1);
+    PolicySourceConfig source = config.getSources().get(0);
+    assertThat(source.getKind()).isEqualTo(SourceKind.OPAMP);
+    assertThat(source.getFormat()).isEqualTo(SourceFormat.JSONKEYVALUE);
+    assertThat(source.getLocation()).isEqualTo("vendor");
+    assertThat(source.getMappings()).hasSize(1);
+    assertThat(source.getMappings().get(0).getSourceKey()).isEqualTo("sampling_rate");
+    assertThat(source.getMappings().get(0).getPolicyType()).isEqualTo("trace_sampling_rate_policy");
+  }
+
+  @Test
+  void readFromConfigPropertiesReadsYamlWhenYamlPathProvided() throws Exception {
+    Path configPath = tempDir.resolve("policy-init.yaml");
+    Files.write(configPath, minimalYamlConfig().getBytes(StandardCharsets.UTF_8));
+
+    PolicyInitConfig config = configFromPaths(configPath.toString(), null);
+
+    assertThat(config.getSources()).hasSize(1);
+    PolicySourceConfig source = config.getSources().get(0);
+    assertThat(source.getKind()).isEqualTo(SourceKind.OPAMP);
+    assertThat(source.getFormat()).isEqualTo(SourceFormat.JSONKEYVALUE);
+    assertThat(source.getMappings()).hasSize(1);
+  }
+
+  @Test
+  void readFromConfigPropertiesReturnsNullOnFileReadFailure() {
+    Path missing = tempDir.resolve("missing-policy-init.json");
+
+    assertThat(configFromPaths(null, missing.toString())).isNull();
+  }
+
+  @Test
+  void readFromConfigPropertiesReturnsNullOnParseFailure() throws Exception {
+    Path badJson = tempDir.resolve("bad-policy-init.json");
+    Files.write(badJson, "{}".getBytes(StandardCharsets.UTF_8));
+
+    assertThat(configFromPaths(null, badJson.toString())).isNull();
+  }
+
+  private static PolicyInitConfig configFromPaths(String yamlPath, String jsonPath) {
+    ConfigProperties config = mock(ConfigProperties.class);
+    when(config.getString(PolicyInitConfig.POLICY_INIT_CONFIG_PROPERTY_YAML)).thenReturn(yamlPath);
+    when(config.getString(PolicyInitConfig.POLICY_INIT_CONFIG_PROPERTY_JSON)).thenReturn(jsonPath);
+    return PolicyInitConfig.readFromConfigProperties(config);
+  }
+
+  private static String minimalJsonConfig() {
+    return "{\"sources\":[{\"kind\":\"opamp\",\"format\":\"jsonkeyvalue\",\"location\":\"vendor\","
+        + "\"mappings\":[{\"sourceKey\":\"sampling_rate\",\"policyType\":\"trace_sampling_rate_policy\"}]}]}";
+  }
+
+  private static String jsonWithLocation(String location) {
+    return "{\"sources\":[{\"kind\":\"opamp\",\"format\":\"jsonkeyvalue\",\"location\":\""
+        + location
+        + "\",\"mappings\":[{\"sourceKey\":\"sampling_rate\",\"policyType\":\"trace_sampling_rate_policy\"}]}]}";
+  }
+
+  private static String minimalYamlConfig() {
+    return "sources:\n"
+        + "  - kind: opamp\n"
+        + "    format: jsonkeyvalue\n"
+        + "    location: vendor\n"
+        + "    mappings:\n"
+        + "      - sourceKey: sampling_rate\n"
+        + "        policyType: trace_sampling_rate_policy\n";
+  }
+
+  private static String yamlWithLocation(String location) {
+    return "sources:\n"
+        + "  - kind: opamp\n"
+        + "    format: jsonkeyvalue\n"
+        + "    location: "
+        + location
+        + "\n"
+        + "    mappings:\n"
+        + "      - sourceKey: sampling_rate\n"
+        + "        policyType: trace_sampling_rate_policy\n";
+  }
+}