Create example showing how to expose metrics in the OpenMetrics format

.github/workflows/ci.yml

@@ -26,8 +26,8 @@ jobs:
 
       # Run the tests with each of the different metrics libraries
       - run: cargo test --features=prometheus-exporter,metrics
-      - run: cargo test --features=prometheus-exporter,prometheus --tests
-      - run: cargo test --features=prometheus-exporter,prometheus-client,exemplars-tracing --tests
+      - run: cargo test --features=prometheus-exporter,prometheus
+      - run: cargo test --features=prometheus-exporter,prometheus-client,exemplars-tracing
       # The tests using opentelemetry are currently failing because of this issue:
       # https://github.com/open-telemetry/opentelemetry-rust/issues/1070
       # We should remove the continue-on-error once that is fixed

autometrics/src/exemplars/mod.rs

@@ -23,6 +23,27 @@
 //!   ```http
 //!   Content-Type: application/openmetrics-text; version=1.0.0; charset=utf-8
 //!   ```
+//!
+//!  ```rust
+//!   use http::{header::CONTENT_TYPE, Response};
+//!
+//!   /// Expose the metrics to Prometheus in the OpenMetrics format
+//!   async fn get_metrics() -> Response<String> {
+//!       match autometrics::encode_global_metrics() {
+//!           Ok(metrics) => Response::builder()
+//!               .header(
+//!                   CONTENT_TYPE,
+//!                   "application/openmetrics-text; version=1.0.0; charset=utf-8",
+//!               )
+//!               .body(metrics)
+//!               .unwrap(),
+//!           Err(err) => Response::builder()
+//!               .status(500)
+//!               .body(err.to_string())
+//!               .unwrap(),
+//!       }
+//!   }
+//!   ```
 
 #[cfg(feature = "exemplars-tracing")]
 pub mod tracing;

autometrics/src/exemplars/tracing.rs

@@ -58,7 +58,8 @@ pub(crate) fn get_exemplar() -> Option<TraceLabels> {
 ///
 /// # Example
 /// ```rust
-/// use autometrics::integrations::tracing::AutometricsExemplarExtractor;
+/// use autometrics::exemplars::tracing::AutometricsExemplarExtractor;
+/// use tracing_subscriber::prelude::*;
 ///
 /// fn main() {
 ///     tracing_subscriber::fmt::fmt()