support configuring metrics (#25)

* support configuring metrics

* make tests stable

Author: davidhewitt

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 - Add `span_exporter()` helper to build a span exporter directly in [#20](https://github.com/pydantic/logfire-rust/pull/20)
 - Fix `set_resource` not being called on span processors added with `with_additional_span_processor()` in [#20](https://github.com/pydantic/logfire-rust/pull/20)
+- Add `MetricsOptions` for configuring additional metrics exporters in [#21](https://github.com/pydantic/logfire-rust/pull/21)
 
 ## [v0.1.0] (2025-03-13)
 

Cargo.toml

@@ -35,9 +35,11 @@ nu-ansi-term = "0.50.1"
 chrono = "0.4.39"
 
 [dev-dependencies]
+async-trait = "0.1.88"
 insta = "1.42.1"
 opentelemetry_sdk = { version = "0.28", default-features = false, features = ["testing"] }
 regex = "1.11.1"
+tokio = {version = "1.44.1", features = ["test-util"] }
 ulid = "1.2.0"
 
 [features]

src/bridges/tracing.rs

@@ -233,14 +233,15 @@ mod tests {
     use crate::{
         config::{AdvancedOptions, ConsoleOptions, Target},
         set_local_logfire,
-        tests::{DeterministicExporter, DeterministicIdGenerator},
+        test_utils::{DeterministicExporter, DeterministicIdGenerator},
     };
 
     #[test]
     fn test_tracing_bridge() {
         let exporter = InMemorySpanExporterBuilder::new().build();
 
-        let config = crate::configure()
+        let handler = crate::configure()
+            .local()
             .send_to_logfire(false)
             .with_additional_span_processor(SimpleSpanProcessor::new(Box::new(
                 DeterministicExporter::new(exporter.clone(), file!(), line!()),
@@ -249,11 +250,13 @@ mod tests {
             .with_default_level_filter(LevelFilter::TRACE)
             .with_advanced_options(
                 AdvancedOptions::default().with_id_generator(DeterministicIdGenerator::new()),
-            );
+            )
+            .finish()
+            .unwrap();
 
-        let guard = set_local_logfire(config).unwrap();
+        let guard = set_local_logfire(handler);
 
-        tracing::subscriber::with_default(guard.subscriber.clone(), || {
+        tracing::subscriber::with_default(guard.subscriber().clone(), || {
             tracing::info!("root event"); // FIXME: this event is not emitted
             tracing::info!(name: "root event with value", field_value = 1); // FIXME: this event is not emitted
 
@@ -283,7 +286,7 @@ mod tests {
                 },
                 parent_span_id: 0000000000000000,
                 span_kind: Internal,
-                name: "event src/bridges/tracing.rs:257",
+                name: "event src/bridges/tracing.rs:260",
                 start_time: SystemTime {
                     tv_sec: 0,
                     tv_nsec: 0,
@@ -336,7 +339,7 @@ mod tests {
                             "code.lineno",
                         ),
                         value: I64(
-                            11,
+                            13,
                         ),
                     },
                     KeyValue {
@@ -444,7 +447,7 @@ mod tests {
                             "code.lineno",
                         ),
                         value: I64(
-                            12,
+                            14,
                         ),
                     },
                     KeyValue {
@@ -524,7 +527,7 @@ mod tests {
                             "code.lineno",
                         ),
                         value: I64(
-                            14,
+                            16,
                         ),
                     },
                     KeyValue {
@@ -630,7 +633,7 @@ mod tests {
                             "code.lineno",
                         ),
                         value: I64(
-                            15,
+                            17,
                         ),
                     },
                     KeyValue {
@@ -746,7 +749,7 @@ mod tests {
                             "code.lineno",
                         ),
                         value: I64(
-                            15,
+                            17,
                         ),
                     },
                     KeyValue {
@@ -868,7 +871,7 @@ mod tests {
                             "code.lineno",
                         ),
                         value: I64(
-                            16,
+                            18,
                         ),
                     },
                     KeyValue {
@@ -984,7 +987,7 @@ mod tests {
                             "code.lineno",
                         ),
                         value: I64(
-                            16,
+                            18,
                         ),
                     },
                     KeyValue {
@@ -1106,7 +1109,7 @@ mod tests {
                             "code.lineno",
                         ),
                         value: I64(
-                            17,
+                            19,
                         ),
                     },
                     KeyValue {
@@ -1222,7 +1225,7 @@ mod tests {
                             "code.lineno",
                         ),
                         value: I64(
-                            17,
+                            19,
                         ),
                     },
                     KeyValue {
@@ -1344,7 +1347,7 @@ mod tests {
                             "code.lineno",
                         ),
                         value: I64(
-                            14,
+                            16,
                         ),
                     },
                     KeyValue {
@@ -1455,7 +1458,7 @@ mod tests {
                                         "code.lineno",
                                     ),
                                     value: I64(
-                                        265,
+                                        268,
                                     ),
                                 },
                             ],
@@ -1521,7 +1524,7 @@ mod tests {
                                         "code.lineno",
                                     ),
                                     value: I64(
-                                        266,
+                                        269,
                                     ),
                                 },
                             ],
@@ -1555,15 +1558,18 @@ mod tests {
             ..ConsoleOptions::default()
         };
 
-        let config = crate::configure()
+        let handler = crate::configure()
+            .local()
             .send_to_logfire(false)
             .console_options(console_options.clone())
             .install_panic_handler()
-            .with_default_level_filter(LevelFilter::TRACE);
+            .with_default_level_filter(LevelFilter::TRACE)
+            .finish()
+            .unwrap();
 
-        let guard = set_local_logfire(config).unwrap();
+        let guard = crate::set_local_logfire(handler);
 
-        tracing::subscriber::with_default(guard.subscriber.clone(), || {
+        tracing::subscriber::with_default(guard.subscriber().clone(), || {
             tracing::info!("root event");
             tracing::info!(name: "root event with value", field_value = 1);
 

src/config.rs

@@ -8,7 +8,10 @@ use std::{
     sync::{Arc, Mutex},
 };
 
-use opentelemetry_sdk::trace::{IdGenerator, SpanProcessor};
+use opentelemetry_sdk::{
+    metrics::reader::MetricReader,
+    trace::{IdGenerator, SpanProcessor},
+};
 use tracing::Level;
 
 use crate::ConfigureError;
@@ -160,6 +163,8 @@ pub struct AdvancedOptions {
     pub(crate) base_url: String,
     /// Generator for trace and span IDs.
     pub(crate) id_generator: Option<BoxedIdGenerator>,
+    /// Resource to override default resource detection.
+    pub(crate) resource: Option<opentelemetry_sdk::Resource>,
     //
     //
     // TODO: arguments below supported by Python
@@ -176,6 +181,7 @@ impl Default for AdvancedOptions {
         AdvancedOptions {
             base_url: "https://logfire-api.pydantic.dev".to_string(),
             id_generator: None,
+            resource: None,
         }
     }
 }
@@ -197,6 +203,32 @@ impl AdvancedOptions {
         self.id_generator = Some(BoxedIdGenerator::new(Box::new(generator)));
         self
     }
+
+    /// Set the resource; overrides default resource detection.
+    #[must_use]
+    pub fn with_resource(mut self, resource: opentelemetry_sdk::Resource) -> Self {
+        self.resource = Some(resource);
+        self
+    }
+}
+
+/// Configuration of metrics.
+///
+/// This only has one option for now, but it's a place to add more related options in the future.
+#[derive(Default)]
+pub struct MetricsOptions {
+    /// Sequence of metric readers to be used in addition to the default which exports metrics to Logfire's API.
+    pub(crate) additional_readers: Vec<BoxedMetricReader>,
+}
+
+impl MetricsOptions {
+    /// Add a metric reader to the list of additional readers.
+    #[must_use]
+    pub fn with_additional_reader<T: MetricReader>(mut self, reader: T) -> Self {
+        self.additional_readers
+            .push(BoxedMetricReader::new(Box::new(reader)));
+        self
+    }
 }
 
 /// Wrapper around a `SpanProcessor` to use in `additional_span_processors`.
@@ -251,6 +283,44 @@ impl IdGenerator for BoxedIdGenerator {
     }
 }
 
+/// Wrapper around a `MetricReader` to use in `additional_readers`.
+#[derive(Debug)]
+pub(crate) struct BoxedMetricReader(Box<dyn MetricReader>);
+
+impl BoxedMetricReader {
+    pub fn new(reader: Box<dyn MetricReader>) -> Self {
+        BoxedMetricReader(reader)
+    }
+}
+
+impl MetricReader for BoxedMetricReader {
+    fn register_pipeline(&self, pipeline: std::sync::Weak<opentelemetry_sdk::metrics::Pipeline>) {
+        self.0.register_pipeline(pipeline);
+    }
+
+    fn collect(
+        &self,
+        rm: &mut opentelemetry_sdk::metrics::data::ResourceMetrics,
+    ) -> opentelemetry_sdk::metrics::MetricResult<()> {
+        self.0.collect(rm)
+    }
+
+    fn force_flush(&self) -> opentelemetry_sdk::error::OTelSdkResult {
+        self.0.force_flush()
+    }
+
+    fn shutdown(&self) -> opentelemetry_sdk::error::OTelSdkResult {
+        self.0.shutdown()
+    }
+
+    fn temporality(
+        &self,
+        kind: opentelemetry_sdk::metrics::InstrumentKind,
+    ) -> opentelemetry_sdk::metrics::Temporality {
+        self.0.temporality(kind)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use crate::config::SendToLogfire;

src/exporters.rs

@@ -27,7 +27,7 @@ macro_rules! feature_required {
     }};
 }
 
-/// Build a [`SpanExporter`][opentelemetry::trace::SpanExporter] for passing to
+/// Build a [`SpanExporter`][opentelemetry_sdk::trace::SpanExporter] for passing to
 /// [`with_additional_span_processor()`][crate::LogfireConfigBuilder::with_additional_span_processor].
 ///
 /// This uses `OTEL_EXPORTER_OTLP_PROTOCOL` and `OTEL_EXPORTER_OTLP_TRACES_PROTOCOL` environment
@@ -98,8 +98,21 @@ pub fn span_exporter(
     Ok(RemovePendingSpansExporter::new(span_exporter))
 }
 
-// TODO: make this public?
-pub(crate) fn metric_exporter(
+/// Build a [`PushMetricExporter`][opentelemetry_sdk::metrics::exporter::PushMetricExporter] for passing to
+/// [`with_metrics_options()`][crate::LogfireConfigBuilder::with_metrics_options].
+///
+/// This uses `OTEL_EXPORTER_OTLP_PROTOCOL` and `OTEL_EXPORTER_OTLP_TRACES_PROTOCOL` environment
+/// variables to determine the protocol to use (or otherwise defaults to [`Protocol::HttpBinary`]).
+///
+/// # Errors
+///
+/// Returns an error if the protocol specified by the env var is not supported or if the required feature is not enabled for
+/// the given protocol.
+///
+/// Returns an error if the endpoint is not a valid URI.
+///
+/// Returns an error if any headers are not valid HTTP headers.
+pub fn metric_exporter(
     endpoint: &str,
     headers: Option<HashMap<String, String>>,
 ) -> Result<impl PushMetricExporter + use<>, ConfigureError> {

src/internal/exporters/console.rs

@@ -267,7 +267,7 @@ mod tests {
         config::{ConsoleOptions, Target},
         internal::exporters::console::{ConsoleWriter, SimpleConsoleSpanExporter},
         set_local_logfire,
-        tests::DeterministicExporter,
+        test_utils::DeterministicExporter,
     };
 
     #[test]
@@ -279,7 +279,8 @@ mod tests {
             ..ConsoleOptions::default()
         };
 
-        let config = crate::configure()
+        let handler = crate::configure()
+            .local()
             .send_to_logfire(false)
             .with_additional_span_processor(SimpleSpanProcessor::new(Box::new(
                 DeterministicExporter::new(
@@ -289,12 +290,14 @@ mod tests {
                 ),
             )))
             .install_panic_handler()
-            .with_default_level_filter(LevelFilter::TRACE);
+            .with_default_level_filter(LevelFilter::TRACE)
+            .finish()
+            .unwrap();
 
-        let guard = set_local_logfire(config).unwrap();
+        let guard = set_local_logfire(handler);
 
         std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
-            tracing::subscriber::with_default(guard.subscriber.clone(), || {
+            tracing::subscriber::with_default(guard.subscriber().clone(), || {
                 let root = crate::span!("root span").entered();
                 let _ = crate::span!("hello world span").entered();
                 let _ = crate::span!(level: Level::DEBUG, "debug span");
@@ -316,7 +319,7 @@ mod tests {
         1970-01-01T00:00:03.000000Z DEBUG logfire::internal::exporters::console::tests debug span
         1970-01-01T00:00:05.000000Z DEBUG logfire::internal::exporters::console::tests debug span with explicit parent
         1970-01-01T00:00:07.000000Z  INFO logfire::internal::exporters::console::tests hello world log
-        [2m1970-01-01T00:00:08.000000Z[0m[31m ERROR[0m [2;3mlogfire[0m [1mpanic: oh no![0m [3mlocation[0m=src/internal/exporters/console.rs:303:17, [3mbacktrace[0m=disabled backtrace
+        [2m1970-01-01T00:00:08.000000Z[0m[31m ERROR[0m [2;3mlogfire[0m [1mpanic: oh no![0m [3mlocation[0m=src/internal/exporters/console.rs:306:17, [3mbacktrace[0m=disabled backtrace
         "#);
     }
 }