Splunk specific file based configuration fields

specification/configuration.md

@@ -239,23 +239,96 @@ are required.
     a deprecation warning and suggest an alternate method. For example:
 
     ```txt
-    jaeger-thrift-splunk trace exporter is deprecated and may be removed in a future major release. Use the default 
-    OTLP exporter instead, or set the SPLUNK_REALM and SPLUNK_ACCESS_TOKEN environment variables to send 
+    jaeger-thrift-splunk trace exporter is deprecated and may be removed in a future major release. Use the default
+    OTLP exporter instead, or set the SPLUNK_REALM and SPLUNK_ACCESS_TOKEN environment variables to send
     telemetry directly to Splunk Observability Cloud.
     ```
 
 - `OTEL_TRACES_SAMPLER`
   - Distribution MUST default to `always_on`
     (not OpenTelemetry default)
 
-In addition to environment variables, other ways of defining configuration also exist:
-
-- [Java System
-  Properties](https://docs.oracle.com/javase/tutorial/essential/environment/sysprop.html):
-  These properties MUST match the environment variables converting to lower
-  case and replacing underscores with hyphens or periods. For example:
-  system property `splunk.trace-response-header.enabled` is equivalent to environment
-  variable `SPLUNK_TRACE_RESPONSE_HEADER_ENABLED`.
+In addition to environment variables, other ways of defining configuration exist:
+
+### File based configuration
+
+OpenTelemetry's [declarative configuration](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/configuration/README.md#declarative-configuration)
+SHOULD be supported via [`OTEL_EXPERIMENTAL_CONFIG_FILE`](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/configuration/sdk.md#via-otel_experimental_config_file)
+environment variable.
+
+In addition, Splunk specific configuration MUST have their own root-level
+configuration block named `splunk`.
+
+The following is a configuration blueprint covering the common values:
+
+```yaml
+distribution:
+  splunk:
+    profiling:
+      exporter:
+        otlp_http:
+          endpoint: ""              # SPLUNK_PROFILER_LOGS_ENDPOINT
+      # always_on, cpu_profiler, memory_profiler, callgraphs may contain language specific key value pairs.
+      always_on:
+        cpu_profiler:                 # SPLUNK_PROFILER_ENABLED
+          sampling_interval: 10       # SPLUNK_PROFILER_CALL_STACK_INTERVAL
+        memory_profiler:              # SPLUNK_PROFILER_MEMORY_ENABLED
+        callgraphs:                   # SPLUNK_SNAPSHOT_PROFILER_ENABLED
+          sampling_interval: 10       # SPLUNK_SNAPSHOT_SAMPLING_INTERVAL
+          selection_probability: 0.01 # SPLUNK_SNAPSHOT_SELECTION_PROBABILITY
+    # Language specific configuration.
+    general:
+      # Language distro specific key-value pairs, e.g. for Node.js:
+      runtime_metrics:
+        collection_interval: 30000
+      nextjs_cardinality_reduction: true
+      autoinstrument_packages:
+        - "MyApiService"
+        - "MyOtherService"
+tracer_provider:
+  processors:
+    - batch:
+        exporter:
+          otlp_http:
+            endpoint: ""
+            headers:
+              - name: "X-SF-TOKEN"
+              - value: ""
+meter_provider:
+  readers:
+    - periodic:
+        exporter:
+          otlp_http:
+            endpoint: ""
+            headers:
+              - name: "X-SF-TOKEN"
+              - value: ""
+logger_provider:
+  processors:
+    - batch:
+        exporter:
+            otlp_http:
+              endpoint: ""
+instrumentation/development:
+  js:
+    "@opentelemetry/instrumentation-http":
+      splunk_trace_response_header_enabled: true # SPLUNK_TRACE_RESPONSE_HEADER_ENABLED
+      splunk_capture_uri_parameters:
+        - "userId"
+    "@opentelemetry/instrumentation-redis":
+      splunk_include_command_args: true    # SPLUNK_REDIS_INCLUDE_COMMAND_ARGS
+    "@opentelemetry/instrumentation-pg":
+      disabled: true
+```
+
+Splunk specific keys MUST have the `splunk_` prefix.
+
+#### [Java SystemProperties](https://docs.oracle.com/javase/tutorial/essential/environment/sysprop.html)
+
+These properties MUST match the environment variables converting to lower
+case and replacing underscores with hyphens or periods. For example:
+system property `splunk.trace-response-header.enabled` is equivalent to environment
+variable `SPLUNK_TRACE_RESPONSE_HEADER_ENABLED`.
 
 ### Snapshot Profiler