Add dotnet multi stage image example

integration-examples/splunk-otel-dotnet-docker/Dockerfile

@@ -0,0 +1,42 @@
+#See https://aka.ms/customizecontainer to learn how to customize your debug container and how Visual Studio uses this Dockerfile to build your images for faster debugging.
+
+FROM mcr.microsoft.com/dotnet/aspnet:8.0 AS base
+USER app
+WORKDIR /app
+EXPOSE 8080
+
+FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build
+ARG BUILD_CONFIGURATION=Release
+WORKDIR /src
+COPY ["MultiStageDocker/MultiStageDocker.csproj", "MultiStageDocker/"]
+RUN dotnet restore "./MultiStageDocker/./MultiStageDocker.csproj"
+COPY . .
+WORKDIR "/src/MultiStageDocker"
+RUN dotnet build "./MultiStageDocker.csproj" -c $BUILD_CONFIGURATION -o /app/build
+
+# Add dependencies for splunk-otel-dotnet-install.sh
+RUN apt-get update && \
+	apt-get install -y unzip
+
+# Download Splunk OTel .NET installer
+RUN curl -sSfL https://github.com/signalfx/splunk-otel-dotnet/releases/latest/download/splunk-otel-dotnet-install.sh -O
+
+# Install the distribution
+RUN sh ./splunk-otel-dotnet-install.sh
+
+FROM build AS publish
+ARG BUILD_CONFIGURATION=Release
+RUN dotnet publish "./MultiStageDocker.csproj" -c $BUILD_CONFIGURATION -o /app/publish /p:UseAppHost=false
+
+FROM base AS final
+
+# Copy instrumentation file tree
+WORKDIR "//home/app/.splunk-otel-dotnet"
+COPY --from=build /root/.splunk-otel-dotnet/ .
+
+WORKDIR /app
+COPY --from=publish /app/publish .
+COPY --from=build /src/MultiStageDocker/entrypoint.sh .
+
+ENTRYPOINT ["sh", "entrypoint.sh"]
+CMD ["dotnet", "MultiStageDocker.dll"]

integration-examples/splunk-otel-dotnet-docker/MultiStageDocker.csproj

@@ -0,0 +1,14 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <DockerDefaultTargetOS>Linux</DockerDefaultTargetOS>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.VisualStudio.Azure.Containers.Tools.Targets" Version="1.19.5" />
+  </ItemGroup>
+
+</Project>

integration-examples/splunk-otel-dotnet-docker/Program.cs

@@ -0,0 +1,6 @@
+var builder = WebApplication.CreateBuilder(args);
+var app = builder.Build();
+
+app.MapGet("/", () => "Hello World!");
+
+app.Run();

integration-examples/splunk-otel-dotnet-docker/README.md

@@ -0,0 +1,88 @@
+# Splunk OTel Dotnet & Docker
+
+This example demonstrates the execution of a .NET application within a Docker container, utilizing the Splunk Distribution of OpenTelemetry for .NET.
+The Docker image is constructed using a multi-stage Docker image approach, wherein the build image is more substantial, and the runtime image is a barebone image.
+
+The installation of instrumentation needs to be divided between different stages.
+During the build step, the instrumentation is installed, and subsequently, the outcome is transferred to the final image, eliminating the necessity for additional dependencies specified in a separate build step.
+
+The `entrypoint.sh` is essential for sourcing environment variables from the `instrument.sh` script, which is included with the instrumentation. This ensures the correct setup of environment variables for each platform.
+
+## Instructions
+
+Execute or run points 1-3 manually:
+
+```bash
+docker run -d \
+  -e OTEL_DOTNET_AUTO_TRACES_CONSOLE_EXPORTER_ENABLED=true \
+  -p 8181:8080 \
+  multistagedocker:latest
+```
+
+1. Set `ENV OTEL_DOTNET_AUTO_TRACES_CONSOLE_EXPORTER_ENABLED=true` in the Dockerfile for verification purposes.
+1. Build the Docker image.
+1. Map a random host port (e.g.: 8181) to the container port (8080).
+1. Open your browser and navigate to `http://localhost:8181`.
+1. Verify the execution of instrumentation by examining the container logs, which should now include Activity information. (Refer to the sample output below.)
+
+Sample log output:
+
+```txt
+2023-12-01 15:34:28 info: Microsoft.Hosting.Lifetime[14]
+2023-12-01 15:34:28       Now listening on: http://[::]:8080
+2023-12-01 15:34:28 info: Microsoft.Hosting.Lifetime[0]
+2023-12-01 15:34:28       Application started. Press Ctrl+C to shut down.
+2023-12-01 15:34:28 info: Microsoft.Hosting.Lifetime[0]
+2023-12-01 15:34:28       Hosting environment: Production
+2023-12-01 15:34:28 info: Microsoft.Hosting.Lifetime[0]
+2023-12-01 15:34:28       Content root path: /app
+2023-12-01 15:34:32 Activity.TraceId:            7f34db4b569f6b6dd6c77c1a5d5164e2
+2023-12-01 15:34:32 Activity.SpanId:             87c76863b1d6b603
+2023-12-01 15:34:32 Activity.TraceFlags:         Recorded
+2023-12-01 15:34:32 Activity.ActivitySourceName: OpenTelemetry.Instrumentation.AspNetCore
+2023-12-01 15:34:32 Activity.DisplayName:        GET /
+2023-12-01 15:34:32 Activity.Kind:               Server
+2023-12-01 15:34:32 Activity.StartTime:          2023-12-01T13:34:32.4239711Z
+2023-12-01 15:34:32 Activity.Duration:           00:00:00.0958729
+2023-12-01 15:34:32 Activity.Tags:
+2023-12-01 15:34:32     net.host.name: localhost
+2023-12-01 15:34:32     net.host.port: 8181
+2023-12-01 15:34:32     http.method: GET
+2023-12-01 15:34:32     http.scheme: http
+2023-12-01 15:34:32     http.target: /
+2023-12-01 15:34:32     http.url: http://localhost:8181/
+2023-12-01 15:34:32     http.flavor: 1.1
+2023-12-01 15:34:32     http.user_agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/119.0.0.0 Safari/537.36 Edg/119.0.0.0
+2023-12-01 15:34:32     http.route: /
+2023-12-01 15:34:32     http.status_code: 200
+2023-12-01 15:34:32 Resource associated with Activity:
+2023-12-01 15:34:32     service.name: MultiStageDocker
+2023-12-01 15:34:32     splunk.distro.version: 1.2.0
+2023-12-01 15:34:32     telemetry.distro.name: splunk-otel-dotnet
+2023-12-01 15:34:32     telemetry.distro.version: 1.2.0
+2023-12-01 15:34:32     container.id: 9cc3abcf5e01dd5276768fe5e008ffc0a83cb57073d8dd98dc2e2c79f5620100
+2023-12-01 15:34:32     telemetry.sdk.name: opentelemetry
+2023-12-01 15:34:32     telemetry.sdk.language: dotnet
+2023-12-01 15:34:32     telemetry.sdk.version: 1.6.0
+2023-12-01 15:34:32
+```
+
+## Common known issues
+
+### Visual Studio is not starting the instrumentation
+
+Utilize Visual Studio for constructing the Docker image by right-clicking on the Dockerfile and selecting "Build Docker image." Use Docker Desktop to run the image. It is noteworthy that initiating a container directly from Visual Studio is known to not start the instrumentation.
+
+### instrument.sh is not found
+
+Linux distributions that do not recognize CRLF (Carriage Return Line Feed) file endings may encounter issues when executing the `entrypoint.sh` script. It is necessary to ensure that on such systems, `entrypoint.sh` uses LF (Line Feed) file endings, especially when the file has been modified in a Windows environment.
+
+See more info [here](https://en.wikipedia.org/wiki/Newline#Issues_with_different_newline_formats).
+
+### The docker exec process may not display all environment variables
+
+The environment variables derived from the `instrument.sh` are not visible when the `env` command is executed through `docker exec`. This occurs because `docker exec` initiates a new session, and the environment variables set in the entry point only apply to the `dotnet MultiStageDocker.dll` session.
+
+### Activity log does not appear
+
+Either the instrumentation wasn't configured properly, or there is no action triggering the activity. In this example, opening the browser at `http://localhost:8181` generates HTTP activity.

integration-examples/splunk-otel-dotnet-docker/entrypoint.sh

@@ -0,0 +1,6 @@
+#!/bin/sh
+# Read in the file of environment settings
+. /$HOME/.splunk-otel-dotnet/instrument.sh
+
+# Then run the CMD
+exec "$@"