[dynamic control] Add pipeline config initialization from declarative config or failover to file

[jackshirazi]

Description:

Adding a method to read pipeline initialization from declarative config, or if not present failover to a file in yaml (or a json file).

The declarative config looks like

telemetry_policy:
  sources:
    - kind: opamp
      format: jsonkeyvalue
      location: vendor
      mappings:
        - sourceKey: sampling_rate
          policyType: trace_sampling_rate_policy

If declarative config is not present, the failover file is expected to have the node under telemetry_policy, ie starting at sources as the top-level node

Existing Issue(s):

#2546

Testing:

Added

Documentation:

Added

Outstanding items:

Wiring up the policy pipeline:

• Generic: message -> provider -> policy -> policy handler -> implementer
• eg change sampling rate message -> OpampPolicyProvider -> TraceSamplingRatePolicy -> PolicyStore -> TraceSamplingRatePolicyImplementer

Steps needed for the wiring:

• configuring the pipeline
  • DONE in this PR
• providers reading policies, eg OpampPolicyProvider, FilePolicyProvider, etc
  • DONE: OpampPolicyProvider
• implementers applying policies, eg TraceSamplingRatePolicyImplementer
  • DONE: TraceSamplingRatePolicyImplementer
• policy structures (eg TraceSamplingRatePolicy) that the provider converts messages into
  • DONE: TraceSamplingRatePolicy
• registering config to policy structures (eg "trace_sampling_rate_policy" registered to TraceSamplingRatePolicy)
• initializing policy classes (eg TraceSamplingRatePolicy needs to install a custom sampler)
  • DONE TraceSamplingRatePolicy initialization
• activate configured providers (eg start OpampPolicyprovider reading from it's source)
• register implementers for policies (eg a new TraceSamplingRatePolicy is applied by a TraceSamplingRatePolicyImplementer)
• link the provider to processing policies and applying implementers

[Copilot]

Pull request overview

Adds initialization of dynamic-control’s telemetry policy pipeline from OpenTelemetry declarative config (preferred) with fallback to file-based YAML/JSON config.

Changes:

• Add PolicyInitConfig loaders for declarative config (telemetry_policy.sources) and declarative-first fallback helpers (including via OpenTelemetry / ExtendedOpenTelemetry).
• Add file-based loading from otel.java.experimental.telemetry.policy.init.yaml/json with YAML precedence and warning-on-failure behavior.
• Add unit tests covering declarative vs file fallback selection and error cases.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
dynamic-control/src/main/java/io/opentelemetry/contrib/dynamic/policy/registry/PolicyInitConfig.java	Implements declarative-first init config parsing and file fallback, plus reflective access to “general config” accessor.
dynamic-control/src/test/java/io/opentelemetry/contrib/dynamic/policy/registry/PolicyInitConfigTest.java	Adds tests for YAML/JSON precedence, parse failures, and declarative-vs-file selection paths.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (1)

dynamic-control/src/main/java/io/opentelemetry/contrib/dynamic/policy/registry/json/JsonNodePolicyInitConfigParser.java:55

• JSON init-config parsing now trims/normalizes optional location, but other string fields (kind, format, sourceKey, policyType) are still accepted with leading/trailing whitespace (and even whitespace-only, since requireText only checks isEmpty()). This can lead to hard-to-debug mismatches because mapping keys/policy types are used verbatim downstream. Consider trimming and validating non-blank in requireText (returning the trimmed value), and applying the same normalization to mapping fields for consistency with declarative parsing.

    JsonNode locationNode = objectNode.get("location");
    String location =
        locationNode != null && locationNode.isTextual()
            ? normalizeOptionalText(locationNode.asText())
            : null;

    JsonNode mappingsNode =
        requireArray(objectNode.get("mappings"), "Each source must define a 'mappings' array.");
    List<PolicySourceMappingConfig> mappings = new ArrayList<>();

[jaydeluca]

should we scope this a bit more and add some logging? currently if the method exists but throws a NPE or something we'll fall through and the user might not know why

Suggested change

	} catch (NoSuchMethodException
	| IllegalAccessException
	| InvocationTargetException
	| RuntimeException ignored) {
	// Fall through to backwards-compatible accessor below.
	}
	} catch (NoSuchMethodException ignored) {
	// Method doesn't exist in this runtime version — fall through.
	} catch (IllegalAccessException | InvocationTargetException e) {
	logger.log(Level.WARNING, "Failed to invoke getGeneralConfig via reflection", e);
	}

[jaydeluca]

should we also guard against empty maps?

Suggested change

	if (mappingConfigs == null) {
	if (mappingConfigs == null || mappingConfigs.isEmpty()) {

[jaydeluca]

any reason not to make these all private? I'm assuming ability to access them in tests but just checking

[jaydeluca]

Suggested change

	static ConfigProvider getConfigProvider(@Nullable OpenTelemetry openTelemetry) {
	private static ConfigProvider getConfigProvider(@Nullable OpenTelemetry openTelemetry) {