feat(opentelemetry source): Support per-signal OTLP decoding config (#24822)

* feat(opentelemetry source): Support per-signal OTLP decoding configuration (#24455)

Allow independent configuration of OTLP decoding for logs, metrics, and traces.
Maintains backward compatibility with boolean configuration.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* changelog

* generate component docs

* regen docs

* fixes

* linting

* consolidate tests

* add usage example

* fix trace output

* fix test too

* make generate-component-docs

* address review point

* attempt to fix blocking workflow

* attempt optimal fix

* revert changelog workflow changes

---------

Co-authored-by: Claude <noreply@anthropic.com>

Author: pront

changelog.d/24455_otel_source_per_signal_decoding.enhancement.md

@@ -0,0 +1,21 @@
+The `opentelemetry` source now supports independent configuration of OTLP decoding for logs, metrics, and traces. This allows more granular
+control over which signal types are decoded, while maintaining backward compatibility with the existing boolean configuration.
+
+## Simple boolean form (applies to all signals)
+
+```yaml
+use_otlp_decoding: true  # All signals preserve OTLP format
+# or
+use_otlp_decoding: false # All signals use Vector native format (default)
+```
+
+## Per-signal configuration
+
+```yaml
+use_otlp_decoding:
+  logs: false     # Convert to Vector native format
+  metrics: false  # Convert to Vector native format
+  traces: true    # Preserve OTLP format
+```
+
+authors: pront

src/sources/opentelemetry/config.rs

@@ -47,6 +47,65 @@ pub const LOGS: &str = "logs";
 pub const METRICS: &str = "metrics";
 pub const TRACES: &str = "traces";
 
+/// Configuration for OTLP decoding behavior.
+#[configurable_component]
+#[derive(Clone, Debug, Default, PartialEq, Eq)]
+#[serde(deny_unknown_fields)]
+pub struct OtlpDecodingConfig {
+    /// Whether to use OTLP decoding for logs.
+    ///
+    /// When `true`, logs preserve their OTLP format.
+    /// When `false` (default), logs are converted to Vector's native format.
+    #[serde(default)]
+    pub logs: bool,
+
+    /// Whether to use OTLP decoding for metrics.
+    ///
+    /// When `true`, metrics preserve their OTLP format but are processed as logs.
+    /// When `false` (default), metrics are converted to Vector's native metric format.
+    #[serde(default)]
+    pub metrics: bool,
+
+    /// Whether to use OTLP decoding for traces.
+    ///
+    /// When `true`, traces preserve their OTLP format.
+    /// When `false` (default), traces are converted to Vector's native format.
+    #[serde(default)]
+    pub traces: bool,
+}
+
+impl From<bool> for OtlpDecodingConfig {
+    /// Converts a boolean value to an OtlpDecodingConfig.
+    ///
+    /// This provides backward compatibility with the previous boolean configuration.
+    /// - `true` enables OTLP decoding for all signals
+    /// - `false` disables OTLP decoding for all signals (uses Vector native format)
+    fn from(value: bool) -> Self {
+        Self {
+            logs: value,
+            metrics: value,
+            traces: value,
+        }
+    }
+}
+
+impl OtlpDecodingConfig {
+    /// Returns true if any signal is configured to use OTLP decoding.
+    pub const fn any_enabled(&self) -> bool {
+        self.logs || self.metrics || self.traces
+    }
+
+    /// Returns true if all signals are configured to use OTLP decoding.
+    pub const fn all_enabled(&self) -> bool {
+        self.logs && self.metrics && self.traces
+    }
+
+    /// Returns true if signals have mixed configuration (some enabled, some disabled).
+    pub const fn is_mixed(&self) -> bool {
+        self.any_enabled() && !self.all_enabled()
+    }
+}
+
 /// Configuration for the `opentelemetry` source.
 #[configurable_component(source("opentelemetry", "Receive OTLP data through gRPC or HTTP."))]
 #[derive(Clone, Debug)]
@@ -67,14 +126,36 @@ pub struct OpentelemetryConfig {
     #[serde(default)]
     pub log_namespace: Option<bool>,
 
-    /// Setting this field will override the legacy mapping of OTEL protos to Vector events and use the proto directly.
+    /// Configuration for OTLP decoding behavior.
     ///
-    /// One major caveat here is that the incoming metrics will be parsed as logs but they will preserve the OTLP format.
-    /// This means that components that work on metrics, will not be compatible with this output.
-    /// However, these events can be forwarded directly to a downstream OTEL collector.
-    #[configurable(derived)]
-    #[serde(default)]
-    pub use_otlp_decoding: bool,
+    /// This configuration controls how OpenTelemetry Protocol (OTLP) data is decoded for each
+    /// signal type (logs, metrics, traces). When a signal is configured to use OTLP decoding, the raw OTLP format is
+    /// preserved, allowing the data to be forwarded to downstream OTLP collectors without transformation.
+    /// Otherwise, the signal is converted to Vector's native event format.
+    ///
+    /// Simple boolean form:
+    ///
+    /// ```yaml
+    /// use_otlp_decoding: true  # All signals preserve OTLP format
+    /// # or
+    /// use_otlp_decoding: false # All signals use Vector native format (default)
+    /// ```
+    ///
+    /// Per-signal configuration:
+    ///
+    /// ```yaml
+    /// use_otlp_decoding:
+    ///   logs: false     # Convert to Vector native format
+    ///   metrics: false  # Convert to Vector native format
+    ///   traces: true    # Preserve OTLP format
+    /// ```
+    ///
+    /// **Note:** When OTLP decoding is enabled for metrics:
+    /// - Metrics are parsed as logs while preserving the OTLP format
+    /// - Vector's metric transforms will NOT be compatible with this output
+    /// - The events can be forwarded directly (passthrough) to a downstream OTLP collector
+    #[serde(default, deserialize_with = "bool_or_struct")]
+    pub use_otlp_decoding: OtlpDecodingConfig,
 }
 
 /// Configuration for the `opentelemetry` gRPC server.
@@ -152,18 +233,24 @@ impl GenerateConfig for OpentelemetryConfig {
             http: example_http_config(),
             acknowledgements: Default::default(),
             log_namespace: None,
-            use_otlp_decoding: false,
+            use_otlp_decoding: OtlpDecodingConfig::default(),
         })
         .unwrap()
     }
 }
 
 impl OpentelemetryConfig {
-    fn get_signal_deserializer(
+    pub(crate) fn get_signal_deserializer(
         &self,
         signal_type: OtlpSignalType,
     ) -> vector_common::Result<Option<OtlpDeserializer>> {
-        if self.use_otlp_decoding {
+        let should_use_otlp = match signal_type {
+            OtlpSignalType::Logs => self.use_otlp_decoding.logs,
+            OtlpSignalType::Metrics => self.use_otlp_decoding.metrics,
+            OtlpSignalType::Traces => self.use_otlp_decoding.traces,
+        };
+
+        if should_use_otlp {
             Ok(Some(OtlpDeserializer::new_with_signals(IndexSet::from([
                 signal_type,
             ]))))
@@ -183,6 +270,16 @@ impl SourceConfig for OpentelemetryConfig {
 
         let grpc_tls_settings = MaybeTlsSettings::from_config(self.grpc.tls.as_ref(), true)?;
 
+        // Log info message when using mixed OTLP decoding formats
+        if self.use_otlp_decoding.is_mixed() {
+            info!(
+                message = "Signals with OTLP decoding enabled will preserve raw format; others will use Vector native format.",
+                logs_otlp = self.use_otlp_decoding.logs,
+                metrics_otlp = self.use_otlp_decoding.metrics,
+                traces_otlp = self.use_otlp_decoding.traces,
+            );
+        }
+
         let logs_deserializer = self.get_signal_deserializer(OtlpSignalType::Logs)?;
         let metrics_deserializer = self.get_signal_deserializer(OtlpSignalType::Metrics)?;
         let traces_deserializer = self.get_signal_deserializer(OtlpSignalType::Traces)?;
@@ -352,13 +449,13 @@ impl SourceConfig for OpentelemetryConfig {
             }
         };
 
-        let logs_output = if self.use_otlp_decoding {
+        let logs_output = if self.use_otlp_decoding.logs {
             SourceOutput::new_maybe_logs(DataType::Log, Definition::any()).with_port(LOGS)
         } else {
             SourceOutput::new_maybe_logs(DataType::Log, schema_definition).with_port(LOGS)
         };
 
-        let metrics_output = if self.use_otlp_decoding {
+        let metrics_output = if self.use_otlp_decoding.metrics {
             SourceOutput::new_maybe_logs(DataType::Log, Definition::any()).with_port(METRICS)
         } else {
             SourceOutput::new_metrics().with_port(METRICS)

src/sources/opentelemetry/integration_tests.rs

@@ -62,7 +62,7 @@ async fn receive_logs_legacy_namespace() {
             },
             acknowledgements: Default::default(),
             log_namespace: Default::default(),
-            use_otlp_decoding: false,
+            use_otlp_decoding: false.into(),
         };
 
         let (sender, logs_output, _) = new_source(EventStatus::Delivered, LOGS.to_string());
@@ -161,7 +161,7 @@ async fn receive_trace() {
             },
             acknowledgements: Default::default(),
             log_namespace: Default::default(),
-            use_otlp_decoding: false,
+            use_otlp_decoding: false.into(),
         };
 
         let (sender, trace_output, _) = new_source(EventStatus::Delivered, TRACES.to_string());
@@ -266,7 +266,7 @@ async fn receive_metric() {
             },
             acknowledgements: Default::default(),
             log_namespace: Default::default(),
-            use_otlp_decoding: false,
+            use_otlp_decoding: false.into(),
         };
 
         let (sender, metrics_output, _) = new_source(EventStatus::Delivered, METRICS.to_string());