Add ASP.NET example for metrics (#4381)

OpenTelemetry.sln

@@ -193,7 +193,9 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "customizing-the-sdk", "docs
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "learning-more-instruments", "docs\metrics\learning-more-instruments\learning-more-instruments.csproj", "{E7F491CC-C37E-4A56-9CA7-8F77F59E0614}"
 EndProject
-Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "getting-started", "docs\metrics\getting-started\getting-started.csproj", "{EA60B549-F712-4ABE-8E44-FCA83B78C06E}"
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "getting-started-console", "docs\metrics\getting-started-console\getting-started-console.csproj", "{EA60B549-F712-4ABE-8E44-FCA83B78C06E}"
+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "getting-started-aspnetcore", "docs\metrics\getting-started-aspnetcore\getting-started-aspnetcore.csproj", "{0C3E7D40-E0B3-4B77-8139-0E85C3600688}"
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "extending-the-sdk", "docs\metrics\extending-the-sdk\extending-the-sdk.csproj", "{1F9D7748-D099-4E25-97F5-9C969D6FF969}"
 EndProject
@@ -421,6 +423,10 @@ Global
 		{EA60B549-F712-4ABE-8E44-FCA83B78C06E}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{EA60B549-F712-4ABE-8E44-FCA83B78C06E}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{EA60B549-F712-4ABE-8E44-FCA83B78C06E}.Release|Any CPU.Build.0 = Release|Any CPU
+		{0C3E7D40-E0B3-4B77-8139-0E85C3600688}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{0C3E7D40-E0B3-4B77-8139-0E85C3600688}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{0C3E7D40-E0B3-4B77-8139-0E85C3600688}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{0C3E7D40-E0B3-4B77-8139-0E85C3600688}.Release|Any CPU.Build.0 = Release|Any CPU
 		{1F9D7748-D099-4E25-97F5-9C969D6FF969}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{1F9D7748-D099-4E25-97F5-9C969D6FF969}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{1F9D7748-D099-4E25-97F5-9C969D6FF969}.Release|Any CPU.ActiveCfg = Release|Any CPU
@@ -569,6 +575,7 @@ Global
 		{64E3D8BB-93AB-4571-93F7-ED8D64DFFD06} = {5B7FB835-3FFF-4BC2-99C5-A5B5FAE3C818}
 		{E7F491CC-C37E-4A56-9CA7-8F77F59E0614} = {3277B1C0-BDFE-4460-9B0D-D9A661FB48DB}
 		{EA60B549-F712-4ABE-8E44-FCA83B78C06E} = {3277B1C0-BDFE-4460-9B0D-D9A661FB48DB}
+		{0C3E7D40-E0B3-4B77-8139-0E85C3600688} = {3277B1C0-BDFE-4460-9B0D-D9A661FB48DB}
 		{1F9D7748-D099-4E25-97F5-9C969D6FF969} = {3277B1C0-BDFE-4460-9B0D-D9A661FB48DB}
 		{81234AFA-B4E7-4D0D-AB97-FD559C78EDA2} = {3277B1C0-BDFE-4460-9B0D-D9A661FB48DB}
 		{1F6CC903-04C9-4E7C-B388-C215C467BFB9} = {3862190B-E2C5-418E-AFDC-DB281FB5C705}

README.md

@@ -40,7 +40,8 @@ repo.
 If you are new here, please read the getting started docs:
 
 * [logs](./docs/logs/getting-started/README.md)
-* [metrics](./docs/metrics/getting-started/README.md)
+* metrics: [ASP.NET Core](./docs/metrics/getting-started-aspnetcore/README.md) |
+  [Console](./docs/metrics/getting-started-console/README.md)
 * traces: [ASP.NET Core](./docs/trace/getting-started-aspnetcore/README.md) |
   [Console](./docs/trace/getting-started-console/README.md)
 

docs/metrics/customizing-the-sdk/README.md

@@ -2,7 +2,8 @@
 
 ## MeterProvider
 
-As shown in the [getting-started](../getting-started/README.md) doc, a valid
+As shown in the [getting-startedgetting started in 5 minutes - Console
+Application](../getting-started-console/README.md) doc, a valid
 [`MeterProvider`](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/metrics/sdk.md#meterprovider)
 must be configured and built to collect metrics with OpenTelemetry .NET Sdk.
 `MeterProvider` holds all the configuration for metrics like MetricReaders,

docs/metrics/getting-started-aspnetcore/Program.cs

@@ -0,0 +1,38 @@
+// <copyright file="Program.cs" company="OpenTelemetry Authors">
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+using System.Diagnostics;
+using OpenTelemetry.Metrics;
+using OpenTelemetry.Resources;
+
+var appBuilder = WebApplication.CreateBuilder(args);
+
+// Configure OpenTelemetry with metrics and auto-start.
+appBuilder.Services.AddOpenTelemetry()
+    .ConfigureResource(builder => builder
+        .AddService(serviceName: "OTel.NET Getting Started"))
+    .WithMetrics(builder => builder
+        .AddAspNetCoreInstrumentation()
+        .AddConsoleExporter((exporterOptions, metricReaderOptions) =>
+        {
+            metricReaderOptions.PeriodicExportingMetricReaderOptions.ExportIntervalMilliseconds = 1000;
+        }));
+
+var app = appBuilder.Build();
+
+app.MapGet("/", () => $"Hello from OpenTelemetry Metrics!");
+
+app.Run();

docs/metrics/getting-started-aspnetcore/README.md

@@ -0,0 +1,102 @@
+# Getting Started with OpenTelemetry .NET in 5 Minutes - ASP.NET Core Application
+
+First, download and install the [.NET
+SDK](https://dotnet.microsoft.com/download) on your computer.
+
+Create a new web application:
+
+```sh
+dotnet new web -o aspnetcoreapp
+cd aspnetcoreapp
+```
+
+Install the
+[OpenTelemetry.Exporter.Console](../../../src/OpenTelemetry.Exporter.Console/README.md),
+[OpenTelemetry.Extensions.Hosting](../../../src/OpenTelemetry.Extensions.Hosting/README.md),
+and
+[OpenTelemetry.Instrumentation.AspNetCore](../../../src/OpenTelemetry.Exporter.Console/README.md)
+packages:
+
+```sh
+dotnet add package OpenTelemetry.Exporter.Console --prerelease
+dotnet add package OpenTelemetry.Extensions.Hosting --prerelease
+dotnet add package OpenTelemetry.Instrumentation.AspNetCore --prerelease
+```
+
+> **Note** This quickstart guide uses prerelease packages. For a quickstart
+> which only relies on stable packages see: [Getting Started - Console
+> Application](../getting-started-console/README.md). For more information about
+> when instrumentation will be marked as stable see: [Instrumentation-1.0.0
+> milestone](https://github.com/open-telemetry/opentelemetry-dotnet/milestone/23).
+
+Update the `Program.cs` file with the code from [Program.cs](./Program.cs).
+
+Run the application again (using `dotnet run`) and then browse to the url shown
+in the console for your application (ex `http://localhost:5154`). You should see
+the trace output from the console.
+
+```text
+Export http.server.duration, Measures the duration of inbound HTTP requests., Unit: ms, Meter: OpenTelemetry.Instrumentation.AspNetCore/1.0.0.0
+(2023-04-11T21:49:43.6915232Z, 2023-04-11T21:50:50.6564690Z] http.flavor: 1.1 http.method: GET http.route: / http.scheme: http http.status_code: 200 net.host.name: localhost net.host.port: 5000 Histogram
+Value: Sum: 3.5967 Count: 11 Min: 0.073 Max: 2.5539
+(-Infinity,0]:0
+(0,5]:11
+(5,10]:0
+(10,25]:0
+(25,50]:0
+(50,75]:0
+(75,100]:0
+(100,250]:0
+(250,500]:0
+(500,750]:0
+(750,1000]:0
+(1000,2500]:0
+(2500,5000]:0
+(5000,7500]:0
+(7500,10000]:0
+(10000,+Infinity]:0
+```
+
+Congratulations! You are now collecting metrics using OpenTelemetry.
+
+What does the above program do?
+
+The program uses the
+[OpenTelemetry.Instrumentation.AspNetCore](../../../src/OpenTelemetry.Instrumentation.AspNetCore/README.md)
+package to automatically create metrics for incoming ASP.NET Core requests, uses
+the
+[OpenTelemetry.Exporter.Console](../../../src/OpenTelemetry.Exporter.Console/README.md)
+package to write metrics to the console every 1000 milliseconds. This is done by
+configuring an OpenTelemetry
+[MeterProvider](../customizing-the-sdk/README.MD#meterprovider) using extension
+methods and setting it to auto-start when the host is started:
+
+```csharp
+appBuilder.Services.AddOpenTelemetry()
+    .ConfigureResource(builder => builder
+        .AddService(serviceName: "OTel.NET Getting Started"))
+    .WithMetrics(builder => builder
+        .AddAspNetCoreInstrumentation()
+        .AddConsoleExporter((exporterOptions, metricReaderOptions) =>
+        {
+            metricReaderOptions.PeriodicExportingMetricReaderOptions.ExportIntervalMilliseconds = 1000;
+        })
+    );
+```
+
+> **Note**
+> The `AddOpenTelemetry` extension is part of the
+[OpenTelemetry.Extensions.Hosting](../../../src/OpenTelemetry.Extensions.Hosting/README.md)
+package.
+
+The index route ("/") is set up to write out a greeting message on the response:
+
+```csharp
+app.MapGet("/", () => $"Hello from OpenTelemetry Metrics!");
+```
+
+## Learn more
+
+* [Getting Started with Prometheus and Grafana](../getting-started-prometheus-grafana/README.md)
+* [Customizing OpenTelemetry .NET SDK](../customizing-the-sdk/README.md)
+* [Extending the OpenTelemetry .NET SDK](../extending-the-sdk/README.md)

docs/metrics/getting-started-aspnetcore/appsettings.Development.json

@@ -0,0 +1,9 @@
+{
+  "DetailedErrors": true,
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  }
+}

docs/metrics/getting-started-aspnetcore/appsettings.json

@@ -0,0 +1,9 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  },
+  "AllowedHosts": "*"
+}

docs/metrics/getting-started-aspnetcore/getting-started-aspnetcore.csproj

@@ -0,0 +1,15 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFrameworks>net6.0;net7.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry.Exporter.Console\OpenTelemetry.Exporter.Console.csproj" />
+    <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry.Extensions.Hosting\OpenTelemetry.Extensions.Hosting.csproj" />
+    <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry.Instrumentation.AspNetCore\OpenTelemetry.Instrumentation.AspNetCore.csproj" />
+  </ItemGroup>
+
+</Project>

docs/metrics/getting-started-prometheus-grafana/README.md

@@ -11,8 +11,9 @@
 
 ## Export metrics from the application
 
-It is highly recommended to go over the [getting-started](../getting-started/README.md)
+It is highly recommended to go over the [getting started in 5 minutes - Console
-doc before following along this document.
+Application](../getting-started-console/README.md) doc before following along
+this document.
 
 Create a new console application and run it:
 
@@ -33,8 +34,8 @@ Now, we are going to make some small tweaks to the example in the
 getting-started metrics `Program.cs` to make the metrics available via
 OpenTelemetry Prometheus Exporter.
 
-First, copy and paste everything from getting-started
+First, copy and paste everything from getting-started metrics
-metrics [example](../getting-started/Program.cs) to the Program.cs file of the
+[example](../getting-started-console/Program.cs) to the Program.cs file of the
 new console application (getting-started-prometheus) we've created.
 
 And replace the below line:

src/OpenTelemetry.Exporter.Console/README.md

@@ -21,7 +21,8 @@ See the individual "getting started" examples depending on the signal being
 used:
 
 * [Logs](../../docs/logs/getting-started/Program.cs)
-* [Metrics](../../docs/metrics/getting-started/Program.cs)
+* Metrics: [ASP.NET Core](../../docs/metrics/getting-started-aspnetcore/README.md)
+  | [Console](../../docs/metrics/getting-started-console/README.md)
 * Traces: [ASP.NET Core](../../docs/trace/getting-started-aspnetcore/README.md)
   | [Console](../../docs/trace/getting-started-console/README.md)
 

src/OpenTelemetry/README.md

@@ -53,9 +53,11 @@ OpenTelemetry logging.
 
 If you are new to
 [metrics](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/metrics/sdk.md),
-it is first recommended to follow the [getting started in 5
+it is recommended to first follow the [getting started in 5 minutes - ASP.NET
-minutes](../../docs/metrics/getting-started/README.md) guide to get up and
+Core Application](../../docs/metrics/getting-started-aspnetcore/README.md) guide
-running.
+or the [getting started in 5 minutes - Console
+Application](../../docs/metrics/getting-started-console/README.md) guide to get up
+and running.
 
 For a more detailed explanation of SDK metric features see [Customizing
 OpenTelemetry .NET SDK for