refactor: split telemetry module

src/telemetry/metrics.rs

@@ -1,9 +1,5 @@
-use crate::error::AppError;
-use opentelemetry::{KeyValue, metrics::MeterProvider};
-use opentelemetry_prometheus_text_exporter::PrometheusExporter;
-use opentelemetry_sdk::{Resource, metrics::SdkMeterProvider};
+use opentelemetry::{KeyValue, metrics::Meter};
 use std::time::Duration;
-use tracing_subscriber::{EnvFilter, layer::SubscriberExt, util::SubscriberInitExt};
 
 #[derive(Clone, Debug)]
 pub struct AppMetrics {
@@ -16,6 +12,42 @@ pub struct AppMetrics {
 }
 
 impl AppMetrics {
+    #[must_use]
+    pub fn new(meter: &Meter) -> Self {
+        Self {
+            http_requests: meter
+                .u64_counter("http.server.requests")
+                .with_description("Total HTTP requests")
+                .with_unit("requests")
+                .build(),
+            http_errors: meter
+                .u64_counter("http.server.errors")
+                .with_description("Total HTTP requests with error status codes")
+                .with_unit("errors")
+                .build(),
+            http_request_duration: meter
+                .f64_histogram("http.server.request.duration")
+                .with_description("HTTP request duration")
+                .with_unit("s")
+                .build(),
+            upstream_requests: meter
+                .u64_counter("upstream.client.requests")
+                .with_description("Total upstream requests")
+                .with_unit("requests")
+                .build(),
+            upstream_errors: meter
+                .u64_counter("upstream.client.errors")
+                .with_description("Total failed upstream requests")
+                .with_unit("errors")
+                .build(),
+            upstream_request_duration: meter
+                .f64_histogram("upstream.client.request.duration")
+                .with_description("Upstream request duration")
+                .with_unit("s")
+                .build(),
+        }
+    }
+
     pub fn record_http_request(&self, method: &str, path: &str, status: u16, duration: Duration) {
         let is_error = status_is_error(status);
         let status = status.to_string();
@@ -54,120 +86,6 @@ impl AppMetrics {
     }
 }
 
-pub struct Telemetry {
-    provider: SdkMeterProvider,
-    exporter: PrometheusExporter,
-    metrics: AppMetrics,
-}
-
-impl Telemetry {
-    #[must_use]
-    pub fn new(service_name: &str) -> Self {
-        let exporter = PrometheusExporter::builder().build();
-        let provider = SdkMeterProvider::builder()
-            .with_reader(exporter.clone())
-            .with_resource(
-                Resource::builder_empty()
-                    .with_service_name(service_name.to_owned())
-                    .build(),
-            )
-            .build();
-        let meter = provider.meter(env!("CARGO_PKG_NAME"));
-        let metrics = AppMetrics {
-            http_requests: meter
-                .u64_counter("http.server.requests")
-                .with_description("Total HTTP requests")
-                .with_unit("requests")
-                .build(),
-            http_errors: meter
-                .u64_counter("http.server.errors")
-                .with_description("Total HTTP requests with error status codes")
-                .with_unit("errors")
-                .build(),
-            http_request_duration: meter
-                .f64_histogram("http.server.request.duration")
-                .with_description("HTTP request duration")
-                .with_unit("s")
-                .build(),
-            upstream_requests: meter
-                .u64_counter("upstream.client.requests")
-                .with_description("Total upstream requests")
-                .with_unit("requests")
-                .build(),
-            upstream_errors: meter
-                .u64_counter("upstream.client.errors")
-                .with_description("Total failed upstream requests")
-                .with_unit("errors")
-                .build(),
-            upstream_request_duration: meter
-                .f64_histogram("upstream.client.request.duration")
-                .with_description("Upstream request duration")
-                .with_unit("s")
-                .build(),
-        };
-
-        Self {
-            provider,
-            exporter,
-            metrics,
-        }
-    }
-
-    #[must_use]
-    pub fn metrics(&self) -> AppMetrics {
-        self.metrics.clone()
-    }
-
-    pub fn render_prometheus(&self) -> Result<String, AppError> {
-        let mut output = Vec::new();
-        self.exporter
-            .export(&mut output)
-            .map_err(|_| AppError::Internal)?;
-        String::from_utf8(output).map_err(|_| AppError::Internal)
-    }
-
-    pub fn shutdown(self) -> Result<(), AppError> {
-        self.provider.shutdown().map_err(|_| AppError::Internal)
-    }
-}
-
-pub fn init_tracing() {
-    let env_filter = EnvFilter::try_from_default_env()
-        .unwrap_or_else(|_| EnvFilter::new("pokedex_api=info,tower_http=info"));
-
-    tracing_subscriber::registry()
-        .with(env_filter)
-        .with(tracing_subscriber::fmt::layer().json())
-        .init();
-}
-
 const fn status_is_error(status: u16) -> bool {
     status >= 400
 }
-
-#[cfg(test)]
-mod tests {
-    use super::Telemetry;
-    use std::time::Duration;
-
-    #[test]
-    fn records_http_and_upstream_metrics_in_prometheus_text_format() {
-        let telemetry = Telemetry::new("test-service");
-        let metrics = telemetry.metrics();
-
-        metrics.record_http_request("GET", "/pokemon/{name}", 200, Duration::from_millis(10));
-        metrics.record_upstream_request(
-            "pokeapi",
-            "pokemon_species",
-            true,
-            Duration::from_millis(5),
-        );
-        let rendered = telemetry
-            .render_prometheus()
-            .expect("metrics should render as text");
-
-        assert!(rendered.contains("http_server_requests"));
-        assert!(rendered.contains("upstream_client_requests"));
-        assert!(rendered.contains("service_name=\"test-service\""));
-    }
-}

src/telemetry/mod.rs

@@ -0,0 +1,56 @@
+mod metrics;
+mod tracing;
+
+use crate::error::AppError;
+use opentelemetry::metrics::MeterProvider;
+use opentelemetry_prometheus_text_exporter::PrometheusExporter;
+use opentelemetry_sdk::{Resource, metrics::SdkMeterProvider};
+
+pub use metrics::AppMetrics;
+pub use tracing::init_tracing;
+
+pub struct Telemetry {
+    provider: SdkMeterProvider,
+    exporter: PrometheusExporter,
+    metrics: AppMetrics,
+}
+
+impl Telemetry {
+    #[must_use]
+    pub fn new(service_name: &str) -> Self {
+        let exporter = PrometheusExporter::builder().build();
+        let provider = SdkMeterProvider::builder()
+            .with_reader(exporter.clone())
+            .with_resource(
+                Resource::builder_empty()
+                    .with_service_name(service_name.to_owned())
+                    .build(),
+            )
+            .build();
+        let meter = provider.meter(env!("CARGO_PKG_NAME"));
+        let metrics = AppMetrics::new(&meter);
+
+        Self {
+            provider,
+            exporter,
+            metrics,
+        }
+    }
+
+    #[must_use]
+    pub fn metrics(&self) -> AppMetrics {
+        self.metrics.clone()
+    }
+
+    pub fn render_prometheus(&self) -> Result<String, AppError> {
+        let mut output = Vec::new();
+        self.exporter
+            .export(&mut output)
+            .map_err(|_| AppError::Internal)?;
+        String::from_utf8(output).map_err(|_| AppError::Internal)
+    }
+
+    pub fn shutdown(self) -> Result<(), AppError> {
+        self.provider.shutdown().map_err(|_| AppError::Internal)
+    }
+}

src/telemetry/tracing.rs

@@ -0,0 +1,11 @@
+use tracing_subscriber::{EnvFilter, layer::SubscriberExt, util::SubscriberInitExt};
+
+pub fn init_tracing() {
+    let env_filter = EnvFilter::try_from_default_env()
+        .unwrap_or_else(|_| EnvFilter::new("pokedex_api=info,tower_http=info"));
+
+    tracing_subscriber::registry()
+        .with(env_filter)
+        .with(tracing_subscriber::fmt::layer().json())
+        .init();
+}