Spike

Author: hannahchan

src/OpenTelemetry.Exporter.Prometheus/PrometheusExporterApplicationBuilderExtensions.cs

@@ -18,6 +18,7 @@
 
 using System;
 using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Routing;
 using Microsoft.Extensions.DependencyInjection;
 using OpenTelemetry.Exporter;
 using OpenTelemetry.Exporter.Prometheus;
@@ -149,6 +150,52 @@ public static IApplicationBuilder UseOpenTelemetryPrometheusScrapingEndpoint(
                     builder.UseMiddleware<PrometheusExporterMiddleware>(meterProvider);
                 });
         }
+
+        /// <summary>
+        /// Adds OpenTelemetry Prometheus scraping endpoint middleware to an
+        /// <see cref="IEndpointRouteBuilder"/> instance.
+        /// </summary>
+        /// <param name="endpoints">The <see cref="IEndpointRouteBuilder"/> to add
+        /// middleware to.</param>
+        /// <param name="path">Optional path to use for the branched pipeline.</param>
+        /// <param name="meterProvider">Optional <see cref="MeterProvider"/>
+        /// containing a <see cref="PrometheusExporter"/> otherwise the primary
+        /// SDK provider will be resolved using application services.</param>
+        /// <param name="configureBranchedPipeline">Optional callback to
+        /// configure the branched pipeline. Called before registration of the
+        /// Prometheus middleware.</param>
+        /// <returns>A convention routes for the Prometheus scraping endpoint.</returns>
+        public static IEndpointConventionBuilder MapPrometheusScrapingEndpoint(
+            this IEndpointRouteBuilder endpoints,
+            string path = null,
+            MeterProvider meterProvider = null,
+            Action<IApplicationBuilder> configureBranchedPipeline = null)
+        {
+            var builder = endpoints.CreateApplicationBuilder();
+
+            // Note: Order is important here. MeterProvider is accessed before
+            // GetOptions<PrometheusExporterOptions> so that any changes made to
+            // PrometheusExporterOptions in deferred AddPrometheusExporter
+            // configure actions are reflected.
+            meterProvider ??= builder.ApplicationServices.GetRequiredService<MeterProvider>();
+
+            if (path == null)
+            {
+                var options = builder.ApplicationServices.GetOptions<PrometheusExporterOptions>();
+                path = options.ScrapeEndpointPath ?? PrometheusExporterOptions.DefaultScrapeEndpointPath;
+            }
+
+            if (!path.StartsWith("/"))
+            {
+                path = $"/{path}";
+            }
+
+            configureBranchedPipeline?.Invoke(builder);
+
+            builder.UseMiddleware<PrometheusExporterMiddleware>(meterProvider);
+
+            return endpoints.Map(new PathString(path), builder.Build());
+        }
     }
 }
 #endif